Sound cards and multimedia. Video. Video for Windows is a video standard for Windows. You can burn a movie from a camcorder or laser disk to a hard drive of the computer and save it as a file in AVI format or MPG. Compression is required only for high

Multimedia technology

Digital audio

• Recording / Play Sound Using

• digital signal
• pulse Code Modulation (Pulse Code Modulation)

• Includes

• Analog-Digital Converter (ADC, ADC)
• Digital-analog converter (DAC, DAC)
• Digital storage format
• Digital signal processing
• Digital audifongation protocols

Benefits

• Minimum noise and distortion

• Copy and storage without loss of quality

• Wide digital processing capabilities

• Digital transmission through networks

• Simple integration with other digital media

• Digital synthesis of sound

Sound wave representation in the form of an electrical signal

Frequency, Hz, Heard Range 20 - 20000 Hz

Below

Sounds in the surrounding world - complex combinations

Audio signal path in the digital system

Video digitization

• 1. Discretization (Sample)

• 2. Quantization

• 3. Conversion to a specific format (+ compression)

Sampling

Quantization

Quantization

IRM (PCM)

Varieties of ICM

• Differential (or delta) impulse-code modulation (Dikm) encodes a signal in the form of a difference between the current and previous value. For audible data, this type of modulation reduces the required number of bits on the countdown by about 25%.

• Adaptive dikm (Adikm, ADPCMIt is a type of dikm, which changes the level of quantization step, which allows you to further reduce the requirements for the bandwidth at a given signal ratio and noise.

Digital broadcasting standards

• DIGITAL AUDIO BROADCASTING (DAB)

• HD Radio.

• Digital Radio Mondiale (DRM)

• IN-BAND ON-CHANNEL (IBOC)

Storage technology

• Digital Audio Tape (DAT)

• 32 KHz / 12 Bits,
• 32 KHz, 44.1 KHz, 48 KHz / 16 Bits.
• 96 KHz / 24 Bits

• Compact Disc (CD)

• 44.1 KHz / 16 Bits

• Hard Disk Recorder.

• DVD Audio.

• 192 KHz / 24-Bits

• Minidisc.

• Algorithm compression ATRAC

• Super Audio CD.

• 1 bit DSD modulation / 2,8224 MHz (44.1 kHz x 64)

Storage technology

• + Various file formats

• Without compression
• WAV, AIFF, AU
• Compression without loss
• FLAC, Monkey "S Audio (FileName Extension Ape), WavPack (Filename Extension WV), TTA, Atrac Advanced Lossless, Apple Lossless (FileName Extension M4A), MPEG-4 SLS, MPEG-4 ALS, MPEG-4 DST, Windows Media. Audio Lossless (WMA Lossless) and Shorten (SHN).
• Compression with losses
• MP3, VORBIS, MUSEPACK, AAC, ATRAC AND Windows Media Audio Lossy (WMA Lossy)

The world of sounds surrounds a person constantly. We hear the noise of the surf, the rustling of foliage, the root of the waterfalls, the singing of birds, the cries of animals, the voices of people and, of course, music.

As specialists emphasize, the sound is the most expressive element of the multimedia. It's time for it and we will plunge into the world of digital sounds.

Sound, like many other physical phenomena, with which we face in everyday life, has a wave nature. Sound waves can be distributed in any compressible medium: gases, liquids or solids. In practice, most often have to deal with sound waves propagating in the atmosphere. When the sound is propagated, the air particles lying on the sound propagation line occur.

One of the most important parameters of the sound wave is its frequency - the value, the reverse period of oscillations. The frequency of sound is made to measure in Hertz (Hz) or kiloherts (1 kHz \u003d 1000 Hz). For example, if the sound frequency is 20 Hz, this means that for 1 s. There are 20 full oscillations. With the frequency of oscillations, the wavelength is inextricably linked - the distance that the wave has time to go through one period of oscillations (wavelength \u003d sound speed / period). Obviously, with an increase in frequency, the wavelength decreases: the less period of oscillation, the smaller the distance passes the wave.

Perennial studies prove that the sensitivity of our hearing significantly depends on the sound frequency. The frequency range of sounds that can hear a person is quite large. It is believed that the lower limit of the frequency of hearing sounds is 16 - 20 Hz, the upper - 18 - 20 kHz. Waves with frequencies underlying the frequency range perceived by a person are called infrasound, and underlying higher ultrasound. Neither infraser nor ultrasound does not perceive the human ear.

The sound wave of the simplest form is, for example, a pure sound tone of a certain frequency. However, the sound waves spreading in the air usually have a more complex shape, especially if air particles are subjected to simultaneous exposure to several waves, which, moreover, distributed in various directions. In this case, the phenomenon of interference is observed - the addition of waves.

4.1. Digitizing analog signal

The phrase "Transfer and Record Sound" You probably had to hear more than once, but you could hardly think about the fact that it is not exactly true of reality.

Perhaps the only device in which sound recording was carried out literally, Edison phonograph was. In all other cases, when it comes to "sound recording", actually recorded or the sound itself is written, but information about what air fluctuations at the time of recording.

Currently, two fundamentally uses for recording and transmitting information about sound. various methods - Analog and digital.

In the first case, changes in sound pressure correspond to proportional changes in other physical quantities, for example, electrical voltage. In this case, the electrical voltage changes are the new "carrier" of sound information.

This method of maintaining sound information is analog, and even recently in recording and radio broadcasting, he was the only one. In the analog electronics it is important that the voltage change exactly corresponds to the change in sound pressure. Recall that the amplitude of the sound wave determines the volume of the sound, and its frequency is the height of the soundtone, therefore, for reliable conservation of sound information, the amplitude of the electrical voltage should be proportional to the amplitude of sound oscillations. The voltage frequency, in turn, must correspond to the frequency of sound oscillations.

Thus, it is not difficult to notice that the form of an electrical signal is a complete copy of the sound oscillation form and carries almost complete information about the sound. You can convert sound oscillations to electrical voltage oscillations using a conventional microphone.

Changing the electrical voltage can be put in accordance with the change in the magnetic field of the tape in the tape or the sound stream from the sound track of the film with an optical record. But whatever the new "carrier" of information, the change in its properties should always be proportional to the change in air pressure in the initial sound wave.

The second way to obtain information about sound involves the measurement of the pressure value in the sound wave. The sequence of numbers arising from this is a digital signal - there is nothing but a new expression of source sound oscillations. Naturally, to properly convey the signal form, these measurements must be carried out quite often - at least several times over the period of the highest frequency component of the audio signal.

The digital recording system (transmission) of the audio in the most general form consists of a digital microphone (sound pressure meter), a digital tape recorder or transmitter (for recording or transmitting a large array of numbers) and a digital loudspeaker (sequence converter and a change in sound pressure). In real digital recording systems (transmission) of the audio, the analog electrical transducers are used - microphones and loudspeakers (speakers), and the digital processing is subjected to electrical sound frequency signals.

In general, digital signals are rectangular pulses, which using logical elements include various chains in the electrical circuit. In contrast to the analog electronics, operating the form and voltage of the signal, the digital electronics uses binary signals - signals with discrete voltage levels corresponding to "0" and "1".

The amplitude of the pulse (voltage level) of the digital signal is usually not provided with harsh requirements, provided that the voltage reliably overlaps the levels "0" and "1", which are usually in the range from 0 to +5 V. For example, for the signal level corresponding to " 1 ", voltage can be taken in the range from 2.4 to 5.2 V, and for the level" 0 "- voltage in the range from 0 to 0.8 V.

To calculate binary signals, it is most convenient to use a binary number system, which also operates only with two digits - 0 and 1. In any number system, including binary, the concept of discharge occupies an important place. The discharge is the degree (number) in which the base of the number system is erected. The discharge numbers are among the right left, and the numbering starts from zero.

The largest number that can be recorded in the binary calculus system (however, as in any other) depends on the number of devagments used. So, when using one discharge, you can record only two numbers 0 and 1. If you use 2 discharge, you can record numbers in the range from 0 to 3. In the event that 8 discharges are used, it can be operated by numbers from 0 to 255, and at 16 discharges The range of possible values \u200b\u200bof the number will have borders from 0 to 65 535.

The conversion of an analog signal into digital practically in any system of practical sound recording flows into several stages. First, the analog beep drops on an analog filter, which limits the signal frequency band and eliminates the interference and signal noise. Then, from an analog signal using the sampling / storage circuit, counts are highlighted: with a certain periodicity, an instantaneous level of analog signal is memorized. Further, the counts come to an analog-to-digital converter (ADC) that converts the instantaneous value of each countdown to the digital code, or the number. The resulting sequence of the digital code bit, actually, is the sound signal in digital form. Thus, as a result of the conversion, the continuous analog beep turns into a digital - discrete time and magnitude.

Any multimedia-PC has an audio adapter fee. With the easiest hand of Creative Labs (Singapore), which called its first audioadapters with ring-words Sound Blaster, these devices are often referred to as "soundblasters". The audio adapter gave a computer not only stereo sound, but also the ability to record on external sound signals. As mentioned earlier, the PC disk drives are not at all suitable for recording conventional (analog) sound signals, since they are calculated to write only digital signals, which are practically not distorted when they are transmitted over communication lines.

Audio adapter has Analog-Digital Converter (ADC), Periodically determining the sound signal level and turning this countdown to the digital code. It is written on the outer medium already as a digital signal.

The digital samples of the real beep are stored in the computer's memory (for example, in the form of WAV files). Reviewed from the disk the digital signal is fed to digital Analog Converter (DAC)that converts digital signals into analog. After filtering, they can be reinforced and served on acoustic speakers for playback.

Another way to reproduce sound is its synthesis. When on a synthesizer, some control information is formed by the corresponding output signal. Modern audioadapters synthesize musical sounds in two ways: method frequency Modulation FM (Frequency Modulation) and with help wave synthesis (choosing sounds from the sound table, Wave Table). The second method provides more natural sound.

Standard FM synthesis has medium sound characteristics, therefore, complex filter systems are installed on the maps against possible sound interference.

The essence of WT-synthesis technology is as follows. On the sound card itself, the ROM module with "covered" in it samples of the sound of real musical instruments - samples, and the WT processor with the help of special algorithms, even one tone of the tool reproduces all other sounds. In addition, many manufacturers equip their sound cards by RAM modulators, so it is possible not only to record arbitrary samples, but also load new tools.

Control commands for synthesis of sound can enter the sound card not only from the computer, but also from another, for example, MIDI (Musical Instruments Digital Interface) Devices. Actually, MIDI defines the command transfer protocol standard interface. The MIDI message contains links to notes, and not a record of music as such. In particular, when the sound card receives a similar message, it is decrypted (which notes of which tools should sound) and is being done on the synthesizer. In turn, the computer can control various "intelligent" musical instruments via MIDI with a corresponding interface.

Programs for working with sound can be divided into two large groups: sequencers programs and programs focused on digital technologies Sound records, so-called sound editors.

MIDI sequencers are designed to create music. With the help of sequences, the encoding of musical plates is performed. They are used to arrange, allowing you to "prescribe" individual parties, assign tool timbres, build levels and channel balances (tracks), enter musical strokes (volume accents, time offset, deviations from settings, modulation, etc.). In contrast to the usual essay of music effective use Sequencers requires composer-arrangers of special engineering knowledge. Sound editors programs allow you to record sound in real time on hDD Computer and convert it using digital processing and combining different channels.

· CakeWalk Pro Audio.

Professional multi-track sequencer of TWELVE TONE Systems. Supports up to 64 audio tracks and 256 - MIDI, 64 channel sound effects. CakeWalk was one of the first software products in which support for additional connected modules (plug-in) of a variety of audio effects created for the DirectX interface appeared. Characteristic feature DirectX effects lies in the fact that they all work in real time - just click on the button PREVIEW.And you can configure all the parameters of the selected effect right in the process of playing the sound fragment.

· Sound Forge.

Sound Forge is one of the leaders among sound editors. It has powerful editing features, allows you to embed any plug-in modules that support DirectX technology has a convenient modern interface. Includes two additional components: Batch Converter, which allows you to combine a group of files into one common file, and Spectrum Analysis, representing data in two types (spectrum and phonogram).

· Wavelab.

Steinberg's stereo step is included in the leaderboard among sound editors. It is very fast Package To edit sound. It has a multitude of effects, provides CDR record, spectra analysis, has the ability to work with built-in DirectX and VST plug-in modules, supports many formats sound Files, including MP3. The program opens the sound file in two windows: the first is for a general review, and the second is for specific editing. It is possible to open multiple files at the same time. They can be reduced to the group and are saved as a project. A large array of sound files can be combined into the database.

To get acquainted with the work of software to record and reproduce the audio file, students can on the example of integrated programs to work with the sound available in standard packagesupplied by C. operating system MS Windows of various versions. These include the Windows Media Player program, which allows you to play audio and video files, a simple sound recording program to record sound from a microphone to a hard disk (does not allow you to edit the file). The package of the Windows XP operating system is supplied windows programs Media with Windows Media File Editor is a simple software and interface program that allows you to handle audio files of * WMA, * WMV and MP3 formats. Widely used in user practice and Winamp program, which allows you to highlight the sound files of almost all known formats.

Text in multimedia.

The text in the multimedia application plays a very important role. However, the presentation should not be overloaded with too much textual information - it makes it difficult to perceive.

Text can be entered both directly in the software to develop multimedia applications, and imported from a regular text editor like MS Word applications. In programs for developing POWER POINT and Macromedia Flash. There is a sufficient amount of integrated opportunities for text information processing.

For example, automatic change in the size of the text so that it fits in the selected space and not "fell" from the slide. For this program, the line interval changes, then the font size, and then both of these parameters. Thus, the user no longer need to spend time attempts to fit the text - this happens automatically. Also included automatic numbering of the list items and its change in accordance with the order of their location. In addition to the lists, the programs are also recognized by ordinal numeral, fractions, long and short dash, auto-performance elements with formatted text (for example, ), as well as paired quotes followed by a number. This feature speeds up the creation of presentations, as the user no longer have to constantly make corrections and refinement manually.

There are some principles that need to be guided when creating text dialogs and mappings:

· The text in the lower case is read by approximately 13% faster than the text that is printed entirely in the upper case;

· The top register symbols are most effective for information that should attract attention;

· The text aligned to the right edge is more difficult to read than evenly distributed text with an unnecessary right field;

· The optimal interval between lines is equal to or slightly larger than the height of the characters.

Graphics in Multimedia

Decoration is a very important stage of application development, since, firstly, data presented in graphical form often look better than text, secondly, the use of graphics allows you to highlight the most important points of the presentation. Harmoniously and beautifully decorated presentation is much better perceived by listeners.

There are two ways to represent graphic information in a computer: raster graphics and vector.

When raster graphics The image is divided into elements (Pixels), which determine the size of the picture - x pixels in width and y pixels in height. An important characteristic is the color resolution of raster graphs, determined by the number of bits used to encode the color of each pixel (it is also called the number of bit planes). It is clear that the more bit planes in the file, the more space is required on the disk to save it. There are the following color representation options in graphic files:

· 256-color fileuses 8 bits for each pixel and has a corresponding table of colors, called a palette;

· 16-bit color file It does not use the palette, and 16 bits are given to the preservation of red, green and blue color components of each pixel. There are two options: RGB555 (32768 colors), RGB565 (65536 colors);

· 24-bit color file Like 8 bits for the color components of each pixel. Uses 16.7 million possible color combinations, and therefore the smallest differences between them can be barely seen by the eye;

· 32-bit color filelike 8 bits for color components and 8 bits for the alpha channel of each pixel. The alpha channel determines the level of transparency of each pixel in the image. It is used by software to apply masks to display video data or images one after another.

Another representation method is vector images that are stored as a geometric description of objects that make up the drawing. These images may also include data in raster graphics format. In vector formats, the number of bit planes is not defined in advance.

Graphic editor Oriented to manipulate existing images (mainly scanned) and have a set of tools that allow you to adjust any image aspect.

· Adobe Photoshop.

Professional photo processing package. Supports work with layers and export objects from programs vector graphic. It has a complete set of tools for color correction, retouching, contrast adjustment and colors saturation, masking, creating various color effects. More than 40 filters make it possible to create a variety of special effects. Many plug-in modules have been created by various manufacturers.

· Corel Photopaint

A graphic editor with everything you need to create and edit images, but is inferior to Adobe Photoshop in speed when working with files. Allows you to publish these images on the Internet. Contains tools to work with animated images and slideshows in QuickTime format.

· Photodraw.

Photoodraw is part of Office 2000 and combines the capabilities of vector and raster graphics. It contains a large set of drawn figures and many types of lines for their design, including a variety of art brush strokes or photo images. Photoodraw supports the preservation of the illustrations in the format of most other applications. It includes a large number of different effects that can be applied to images and individual objects, in particular, you can choose the effects of adding the shadow, the tasks of transparency, lubrication, or enhancing the boundaries of objects, give it three-dimensional, promising distortions, as well as special effects that give the image Figure pen, outline, pictorial work and many others.

· PhotoImpact.

The graphic package developed by Ulead Systems is designed not only to create and edit images. It also offers tools for creating and managing photo databases, view image files, creating multimedia slideshows, capture images from the screen, file conversion. Technology Pick-and-Apply (choose and applicable) allows you to use extensions from sets of styles, effects, gradients and textures collected in the Easy Palette menu item, and immediately see the results of the transformations. Supports work with layers, real-time preview, advanced special effects, text placement on a given curve, image retouching tools.

In vector graphics programs, objects and images that are stored as a geometric description exist independently of each other, which allows you to change the layer at any time, the location and any other attributes of the object, creating an arbitrary composition. Modern vector graphics programs also contain tools to work with raster images. Two-dimensional animation uses the traditional method of sample animation. In some cases, tweening is used - automatic generation of intermediate frames. Morphing is also used, deformation of images, a variety of optical effects and cyclic change in light.

A graphic editor with wide opportunities and a huge library of finished images that has already become a classic vector drawing program. The package is designed not only for drawing, but also to prepare graphs and editing raster images. It has excellent file management tools and the ability to show slide movies on the computer display, allows you to draw and work with image layers, supports special effects, including three-dimensional, and has flexible opportunities to work with texts.

Allows you to create vector images. It has the perfectly implemented effect of transparency with gradient properties. The program performs basic operations with raster images: change the depth of color, brightness, contrast, sharpness, use of a blurry filter and other special effects. A huge internal resolution (72 thousand dots per inch) allows you to increase objects up to 2500 times.

· Macromedia Freehand.

Professional graphic editor, allowing, in addition to creating graphic objects, use and process texts using style sheets, spell check and methods for placing text on a page. Allows you to use plug-in modules. Contains the library of special effects and a set of tools for working with color, including the means of multicolor gradient fill.

· Adobe Illustrator

Adobe's Illustrator vector package is designed to create illustrations and development of general page design and focused on the withdrawal of ready-made high-resolution images. The package allows you to create figures and arbitrary shape characters, and then scaling, rotating and deforming them. In addition, Illustrator contains a wide range of tools for working with text and multi-page documents.

ULead Animation Program uses the advantages of GIF files to store multiple images. Unlike video, when an animation, the location and duration of the image appearance on the screen is specified for each image. Since the images can have arbitrary sizes, you can create complex compositions by collecting them from individual parts.

Animation in multimedia

The concept of animation in multimedia includes video creation and processing programs and 3D graphic images.

To edit the video there are a large number of software products. In addition to three-dimensional animation packages, there are highly specialized programs, for example, to create bulk fonts. They also use a variety of animation effects, perform image visualization and allow you to create video files.

· Quick Editor

This is an editor that carries out the basic video operations in the format * MOV and * AVI quickly and simple. It is a good and affordable tool for working with small videos. To work with this editor, the QuickTime version 3 and above must be installed on the computer. This editor does not apply to professional, but for many small projects it is very suitable.

· Adobe Premiere.

The most common digital video editing program. It has a convenient intuitive interface. Supports several video and audio channels, contains a set of transitions between frames, allows you to synchronize sound and image. Supports * MOV and * AVI files. Connecting additional modules (plug-ins) from independent manufacturers expands the program capabilities.

· ULEAD VIDEOSTUDIO.

ULEAD VIDEOSTUDIO is designed for novice users. It provides full support for DV and MPEG-2 formats for digital video. And for the music of the film, you can use music files in * MP3 format or audio tracks from audio. Working with the program is quite easy thanks to the user-friendly interface. The digitization is easily executed using a special Video Wizard module. It helps to go through all the stages of this process and gives the necessary information to start editing. In the video, you can insert credits, take advantage of smooth transitions between individual fragments and add voice or background music to the resulting clip.

· Digital Movie Studio

The program for editing the video of Hitachi. It allows you to create a MPEG file based on video clips and static images, add sound track Or replace it, add titers, date and time, use the transition effects between frames, change the image speed.

Cyberlink, working as an interactive video camera, writes files directly in MPEG-1 format, which saves both time and place on the hard disk. PowerVCR also provides the ability to edit and create titles and converting * AVI files to MPEG-1. It has an intuitive user interface. Allows you to receive a signal from a VCR or camcorder, as well as a TV tuner.

Three-dimensional animation According to the technology resembles a doll: it is necessary to create framework frameworks, identify materials that are tightly inconsistent, to compose everything into a single scene, set lighting and chamber, and then set the number of frames in the film and the movement of items. The movement of objects in three-dimensional space is set by trajectories, key personnel and with the help of formulas connecting the movement of parts of complex structures. After specifying the desired movement, lighting and materials, the visualization process is launched. For some time, the computer calculates all the necessary frames and gives the finished film. The disadvantage is the excessive smoothness of forms and surfaces and some mechanistic movement of objects.

To create realistic three-dimensional images, all new different techniques are invented. To create "uneven" objects, such as hair or smoke, use the technology of forming an object from a variety of particles. Inverse kinematics and other fracther techniques are introduced, new methods for combining video recording and animation effects are arising, which allows you to make scenes and movements more realistic.

In addition, open system technology allows you to work immediately with multiple packages. You can create a model in one package, paint it in another, revive in the third, add video in the fourth. Finally, the functions of many professional packages can be expanded today with additional applications written specifically for the baseline.

ULEAD 3D headlines create a program for presentations, video, multimedia and web pages. The program includes more than 100 automatic masters, many effects. Also contains a huge library of 3D objects and materials plus photorealistic templates and textures.

· 3D Studio Max

One of the most famous packages of 3D animation produced by Kinetix. The program provides the entire process of creating a three-dimensional film: modeling objects and formation of the scene, animation and visualization, video operation. The program interface is one for all modules and has a high degree of interactivity. 3D Studio Max implements advanced animation management capabilities, stores the history of the life of each object and allows you to create a variety of light effects, supports 3D accelerators and has an open architecture, that is, allows third firms to include additional applications in the system.

· Ray Dream Studio.

The program provides a set of professional tools for 3D design and animation. Users can create various models using deformations. These models can use various textures or video images, as well as draw directly on their surface. Full-featured animation uses the blur of movements to give them realism. The visualization parameters allow not only to set the directions of the rays, but also to give the image a view of the hand drawn cartoon.

· Painter 3D

This is a full-featured 3D modeling package. Painter 3D makes it possible to apply texture, shock, light, reflection, and glow objects, and also allows you to automatically update textures. This package supports extensions (Plug-in), which makes it possible to use many standard and additional special effects. The package includes additions for Ray Dream Studio and 3D Studio Max.

Chapter 2.
Using software To create presentations

Often the concept of "multimedia" (in general, a very contradictory term interpretated term) describe as a presentation of information in the form of a combination of text, graphics, video, animation and sound. Analyzing this list, we can say that the first four components (text, graphics, video and animation) are various options for displaying information by graphics, which belong to one environment (and not to "many environments", or Multimedia), namely - To the medium of visual perception.

So, by and large, it is possible to talk about multimedia only when an audio signal is added to the means of exposure to organs of vision. Of course, computer systems are currently known, which are also able to influence the tactile perception of a person and even create smells inherent in one or another visual objects, but so far these applications are either highly specialized applications or are in the infardary stage. Therefore, it can be argued that today's multimedia technologies are technologies that are aimed at transmitting information, actively affecting two channels of perception - vision and hearing.

Since in descriptions multimedia technologies On the printing pages of the audio signal, it is unfairly paid significantly less attention than technology transfer technologies, we decided to fill this gap and asked to tell about how the audition is created for multimedia content, one of the leading Russian specialists in the field of digital recording - Sergey Titova.

ComputerPress: So, we can say that the concepts of "multimedia" does not exist without the sound component. Sergey, could you tell me how this part of the multimedia content is created?

Sergey Titov: In principle, about 80% of all information about the external world we perceive with the help of vision and less than 20% - with a hearing. However, without these 20% it is impossible to do. There are quite a few multimedia applications, where the sound is in the first place and it is he sets the tone to the whole piece. For example, most often the video clip is made under a specific song, and do not write a song under the video. Therefore, in the expression "audiovisual series", it is the word "audio" in the first place.

If we talk about the sound component of the multimedia, then there are two aspects: from the point of view of the consumer and from the point of view of the creator. Apparently, the computer magazine is interesting precisely aspect of creating multimedia content, since it is just created using computer equipment.

Speaking about the means of creating an audio content, it should be noted that the production process requires a fundamentally higher permission when recording files than for the consumption stage, and the technique is needed more high Quality.

Here you can make an analogy with graphics: the designer may subsequently submit a picture in a low permission, for example, for publication on the Internet and at the same time discard some of the information, but the development and editorial process is inevitably conducted taking into account all available information, and decomposed on the layers. The same thing happens when working with sound. Therefore, even if we are talking about an amateur studio, then at least we must talk about the semi-professional level technique.

Speaking about the resolution of the system, we actually mean two parameters: the accuracy of measuring the amplitude of the signal and the frequency of quantization, or the Sampling Rate. In other words, we can measure the amplitude of the output signal very precisely, but it is very rare and as a result of losing most of the information.

KP: How does the process of creating an ok?

S.T.: Any sound pattern is created from some components of the elements. As a DJ on a disco operates with a certain set of initial components, of which it builds a continuous program, and a person engaged in sounding something, has some source materials that it edits and reduces the finished picture. If we are talking about music in its pure form, then at first there is a task to fix these elements, and then collect them in a single picture. This is generally called information.

If we are talking about sounding some video delays (actually, here and you can talk about multimedia content), then you need to collect elements from which sound is escorted, and then "bind" them to the picture, edit these elements and lead to mutual compliance; In this case, individual elements about which this is speech, It is necessary to position in the form, convenient to work.

Computer programs create an interface where there are the same paths and mixer with Lineshek. Under each of these Lineshek, there is its own element, which is subject to one or another modifications. Thus, we create some synthesized sound field, operating with the existing elements, and since this task is in principle creative, then we should be able to modify these elements with certain types of treatment - from a simple editorial board (cut, sort, punctory) to a complex When individual elements can be lengthened or shorten when you can change the character of the sound of each signal.

KP: What software is needed to perform this work, and what special computer equipment is necessary?

S.T.: Special computer equipment is, in fact, only the I / O board, although certain requirements are, of course, are presented to other workstation systems. Software for the organization of the process of sound recording and installation exists in a huge amount: from cheap amateur to semi-professional and highly professional systems. Most of these programs have plug-in-architecture, require high performance from a computer and enough powerful disk subsystems. The fact is that to solve multimedia tasks for the purpose of production, rather than reproduction of content requires machines with a large RAM volume and a powerful processor. The most significant parameter here is not so much the high power of the processor, how much is a good balance of the machine from the point of view of operation of disk subsystems. The latter, as a rule, are SCSI devices that are preferred in the case when you have to operate the data streams that should not be interrupted. Therefore, IDE interfaces are practically not applied. The IDE may have a very high packet data rate (BURST TRANSFER RATE) and the low streaming rate of the data (Sustain Transfer Rate).

In this case, the IDE interface provides that the disk can give data by accumulating them into the buffer, and then pump out from the buffer. SCSI works in a different way, and even if the batch transfer rate is low, the speed of streaming will still be high.

It should also be noted that for the above-mentioned tasks, very large volumes of disk space are required. I will cite a simple example - a 24-bit monofile even at low Sample Rate values, for example, 44.1 kHz, takes 7.5 MB per track per minute.

KP: Is there any technology to store this data more compact?

S.T.: This is a linear PCM (Pulse Code Modulation), which can not be sorry. It can then lie down in mp3, for example, but not at the stage of production, but at the stage of distribution. At the production stage, we must work with linear, noncompressed signals. I will bring the analogy with Photoshop. In order to build a graphic composition, the designer must have a complete picture of what is stored in each layer, to have access to each layer and adjust it separately. All this leads to the fact that the PSD Photoshop format is a decent volume, but allows you to return and make corrections to each layer, without affecting all the others. At that moment, when the picture is completely built, it can be represented in another format, compress with losses or without loss, but I repeat, only when the production stage is fully completed. The same happens with sound - you can reduce the sound composition, only having complete information about all components.

As I said, to create a sound picture, a source library is needed, which corresponds to the task over which you work. Consequently, the video art train is greaterly need pre-written a variety of noises and effects, and DJ is the so-called loops (repeated elements characteristic of dance music). All this material should be stored as files that are understandable for the appropriate program, which works with them. Next, an acoustic system is needed, in order to control it all, and the program must respectively make it possible to manipulate this source material, in which, in fact, is the creative part of the process. Using the computer system as an I / O tool and the program as a tool, the user in accordance with its inner defects edits the source material: increases or reduces the volume of individual elements, changes the timbre color. As a result of the mixing process, the sound engineer should receive a balanced sound picture, which would have a certain aesthetic value. As you see, an analogy with graphics is noticeable even at the terminological level. And whether this picture will cost something, entirely depends on the experience, taste, the talent of this sound engineer (of course, subject to the presence of high-quality equipment).

KP: So far, we meant a purely sound picture, however, speaking of multimedia, it is necessary to consider which means there are means to bring together the sound and image. What is needed for this?

S.T.: Of course, you need a video input-output board, such as the MPEG or Quick Time output format (if you talk about multimedia, the Quick Time will be more convenient).

KP: I suppose it would be interesting to consider a number of practical tasks to voicing the video and on specific examples to find out what equipment and which software is required for the tasks of various levels of complexity. It would be possible to start with the analysis of the options for creating a cheap presentation film ...

For example, let's consider such a case: there is a video filmed by an amateur chamber, and replicas and dialogues are already recorded on the microphone of this chamber. Now we need based on this to make an attractive presentation film with semi-professional sounding. What will you need?

S.T.: If we have the task of achieving a certain perception of sound material (be it even an amateur film), you need to add a lot to the source material: sound effects, background music, so-called background noises (from English background - background, back plan) and so on. Therefore, in any case, there is a need to have multiple tracks at the same time, that is, to read several files at the same time. At the same time, we should have the opportunity to regulate the nature of these files in the production process and edit them (lengthen, shock, etc.).

It is important to note that the system should provide the ability to experiment so that the user can see if this effect is suitable for this place. The system should also allow you to accurately combine sound effects with a sound context, adjust the panorama (if it comes to stereo sound) and so on ...

KP: Well, the task is clear, and the equipment requirements are clear ... Now I would like to get an idea of \u200b\u200bwhat particular equipment and which software can be recommended to solve such a task and in what about the amount it will cost the user.

S.T.: In principle, we need some kind of video editor, but this, as I understand it, a separate topic, and today we must concentrate on the sound component. In any case, in the task you described above, the sound row is subordinate to the video. Therefore, we assume that the video sequence we have, and do not analyze how it is edited. We consider the original option when there is a finishing video sequence and a draft audition. In this draft audio, you need some replicas to cross out, some replace new and so on. It does not matter whether it is a presentation film or game amateur, "we need to insert some artificial audio effects into it. This is due to the fact that the sound from many events in the frame recorded using the camcorder microphone will sound, as they say, is unconvincing.

KP: And where else to take these sounds, how not from the events actually?

S.T.: This is a whole direction called Sound Design, which is to create such sounds, which, being reproduced, would give a convincing sound picture, taking into account the peculiarities of the perception of sounds by the audience. In addition, there is a so-called dramatic underline in the picture of certain sounds that actually sound differently. Of course, if we are talking about the amateur movie and about semi-professional sounding, then some possibilities are cut down, but the tasks in front of us and in this case are the same as before professionals.

In any case, in addition to the draft Chernovik, it is necessary to add some special effects.

KP: So, what equipment do we need to solve this problem?

S.T.: Once again, I emphasize that we are talking about the semi-professional level, that is, about the production of amateur film at home or production of films for studios of cable television, which, in general, close tasks. In order to solve most of the tasks of such a post-sales, you need a Pentium III - 500 MHz machine, preferably 256 RAM, SCSI disk subsystem; The video subsystem does not play a special role, but it is desirable that some hardware decoders of the compressed video are installed there; Accordingly, I / O board is needed, for the simplest amateur works it can be SoundBlaster. As a relatively cheap complex, you can consider the Nuendo software product, which will work almost with any fee and, for example, a cheap SoundBlaster for $ 150. Of course, it is necessary to say here immediately that such a system will have very limited capabilities due to the low quality quality SoundBlaster, which has very low quality microphone amplifiers and very poor quality ADC / DAC.

KP: I would like to hear what does Nuendo do?

S.T.: Nuendo is a software package that has a plug-in-architecture and is designed to solve the tasks of audio production, and it is focused on the tasks of creating a "audio for video", that is, it can be said to be designed just to solve multimedia tasks. The program works with sound and with the image at the same time, while the image for it is the secondary component. Nuendo works under Windows NT, and under Windows 98, and under BE OS. This program is 887 dollars.

The program provides the ability to view the video, laid out in time, and a multi-track system for editing and information of the sound picture.

A feature of the software package is its flexibility, and it is possible to work on a wide range of inexpensive iron. It is common that serious systems work only on equipment with specialized DSP coprocessors. The Nuendo software proves the opposite, because not only provides tools for professional audio selling, but does not require specialized iron and special coprocessors for its needs.

Nuendo provides 200 lanes for mixing, supports surround-sound in such a way that many systems are very pale in comparison with Nuendo.

Nuendo provides qualitative processing in real time on the same processor on which the workstation itself works. Of course, the processing speed will depend on the selected workstation, but the advantage of the program is that it adapts to different processor capacities. A few years ago, serious audio processing was unthinkable without DSP. But today, desktop computers have enough powerful own processors to solve processing tasks in real time. Obviously, the ability to use a regular computer to solve specific tasks, going around without DSP coprocessors, adds flexibility system.

Nuendo is an object-oriented system (that is, a system that operates with metaphor objects: a remote control, indicator, track, etc.), which allows you to fully and fully edit audio files in projects of varying complexity, providing a very convenient and thoughtful interface. Drag-and-Drop means are available when solving various tasks and are particularly intensively used in the processing of crossfields.

An important feature of the program is the almost unlimited system of Undo & Redo editing functions. Nuendo provides not just Undo & Redo operations: Each of the audio shootments has its own editing history, and the system is organized in such a way that after several hundred changes of Undo & Redo, the maximum file required for storing the segment is never increasing more than double compared to Initial volume.

One of the strongest sides of the program is the ability to support surround sound. The system has not only a perfect tool for editing the position of the sound source, but also supports multi-channel surround effects.

KP: What are the use of the user's actions of this program in the voicing process?

S.T.: We listen to that soundtrack that we already have, and we look at which information we need to delete, and what - to edit.

KP: If we are talking about an amateur film, how many tracks can we need?

S.T.: In my experience, it is 16-24 tracks.

KP: What can be placed on such a huge number of tracks?

S.T.: Consider themselves: Chernoviki is occupied by one track, the second - special effects, the third - outband music, and this is not only music, but also dialogues, comments, etc. When all this is going together, it turns out just so the number of tracks.

In addition, 16 or even 24 tracks are a relatively small number. In professional films, their number can translate far over a hundred.

KP: What other options you could recommend for semi-professional use, say, for the same voice of the presentation film at home?

S.T.: Available at the price of the option that I would suggest to consider is a combination of the DIGI-001 boards and Pro Tools 5 LE programs. This option is significantly better in the quality of I / O board and somewhat poorer in software.

Currently, there is a version under Mac OS and literally the other day the version under Windows NT is coming out (I hope that by the time of this magazine, the Windows version of this program will appear in Russia). Windows hardware and Mac OS is absolutely the same.

KP: Is it possible to say that after the appearance of a version under Windows it will be a cheaper solution due to the fact that the workstation itself will cost cheaper?

S.T.: The error that the PC station for dubbing is cheaper than the solution based on Macintosh is very common. But also the opinion that there is cheap stations based on PC and expensive on the basis of Macintosh, incorrectly. There are specific systems to solve specific tasks, and the fact is that it is sometimes built a PC-based system to solve issues related to the creation of multimedia content, it is very difficult because of the random set of cheap IBM-compatible parts is very difficult to collect the machine that would give Optimal performance ...

Regardless of the type of workstation, which will work in the system, DIGI 001 will provide much more opportunities than the SoundBlaster, and there is a board together with the "mathematics" of Pro Tools 5.0 LE only $ 995, that is, in the amount of about the same. How much and the previous solution with the cheapest SoundBlaster'Om.

At the same time, if the Nuendo solution plus the SoundBlaster is a variant in which the possibilities are limited to a cheap board, and the software has very wide opportunities, then the DIGI 001 database solution plus Pro Tools 5.0 LE is a much more powerful fee, and the software is somewhat more modest With its capabilities than Nuendo. In order to be clear what we are talking about, we list the advantages of this decision from the point of view of the I / O board. Digi 001 is a 24-bit ADP-DAC, the ability to simultaneously listen to 24 tracks, the presence on the board eight instead of two inputs, etc. So if, for example, in the course of recording a presentation, you need to record the scene in which six people speaking six microphones are involved, then Digi 001 will be performed with such a task. Add to this independent output to monitors plus work with 24-bit files, while with Nuendo and cheap SaundBlaster you can only work with 16-bit files ...

Pro Tools 5 LE allows you to do practically the same as Nuendo - to carry out non-linear installation, the same manipulations with audio files, plus there is a mini-sequencer that allows you to record music, using MIDI tools.

KP: So what is the difference between professional tasks from semi-professional and what kind of equipment is required for them?

S.T.: First of all, I could tell about the Pro Tools system. In order to prevent possible questions, I want to emphasize once again: you need to distinguish between digidesign pro Tools as a brand and Pro Tools as equipment. Under the trademark Pro Tools hides a whole range of products. The simplest system from this set is exactly the Digi 001, which we talked about the description of semi-professional tasks. This is the easiest option from a whole range of products that ends with systems running on the basis of dozens of workstations tied to a single network.

KP: Let's choose this option that can be applied to sounding simple professional films, serials and so on.

S.T.: The next system that we could consider is Pro Tools 24. To be clear what tasks this system solves, we note that the last series "Xena" was voiced precisely with the help of this technique.

There are versions for both Mac OS and for Windows NT. If we talk about the requirements for NT stations, it should be a serious machine, such as IBM Intelli Station M Pro, 512 RAM. The documentation states that minimum requirements To the processor - Pentium II 233, however, it is realistic to work at least Pentium II 450 and, of course, the SCSI disk system, and the two-port accelerator is required to pull 64 tracks at the same time.

Pro Tools 24 is a set of specialized signal processor boards based on Motorola. It is important to note that this system is based on coprocessors, that is, the machine processor performs the operation associated with the input and display and display of graphics on the screen, and the entire processing of the signal is performed on specialized DSP (Digital Signal Processing) co-composers. This allows you to solve quite complex tasks. It is this technology that is used to sound so-called blockbusters. For example, for the sounding of the "Titanic" (only effects!) The system of 18 workstations combined into the network was used.

Sound in films like "Titanic" is a stunningly complex, changing sound picture. If you analyze the saturated with sounds of a five-decad-minute excerpt from a similar film and write out all the sounds that are used there, it will be a list of hundreds of items. Of course, all these sounds are not heard from the VHS level cassette, and many do not even suspect how difficult the sound picture is created in the film. (Moreover, most of these sounds are created synthetically and in nature do not exist.)

KP: You touched upon the issue of replacing natural sounds to more convincing. Where can I buy such libraries of sounds and how much do they cost?

S.T.: The cost of such libraries is from fifty dollars and higher, up to several thousand dollars. At the same time, all these sounds are mainly applied precisely for easy production at the cable network level. For the professional films, even low-budget (not speaking of expensive), all sounds are written independently.

KP: And what are not suitable sounds from the standard library for a professional film?

S.T.: In principle, I am talking about how this is done in the West or how it should be done, since we often save on our poverty on what you can not save. The fact is that the feature film reflects a certain individual plan of the director, and find the sound in libraries, fully corresponding to this plan, is often almost impossible.

KP: But the sound can be edited, and the possibilities for this, as you say, very wide?

S.T.: There is such a concept as sound timbre. You can emphasize or weaken some components of this timbre, but it cannot be radically changed. That is why all noises for a professional film are written "from scratch", and these professionals are engaged. I will give such an example: in the famous film "Batman returns" the sound of the Batman machine was present. Tell me, please, in which library can you find this sound? Moreover, if we are talking about stereo sound and about Surround technology, then each sound picture is simply unique. For example, if the helicopter flies to the viewer and flies back, it is obvious that such a sound picture is tied to the plot. At the same time, it is not necessary to record real sounds - most often they are created synthetically.

KP: Why can not write sounds from real physical processes and submit them exactly as they meet in life? Why do you need to use any other synthetic?

S.T.: We do not need to recreate the sound of real physical, as you expressed, processes. If a bomb is exploded in three meters from the foreground, then the viewer needs to be transferred at all that the sound that in reality hears the soldiers, which turned out to be near the explosion place! We must transfer a kind of conditional picture that will allow the viewer to submit reality; At the same time, we focus on the features of his perception, on the artistic accents you need and so on.

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Introduction

Multimedia. - this is a picked by all the term denoting an interactive tool for working with graphics, animation, sound and video. Multimedia brings shine in presentation, painting and games, and, moreover, gives pleasure in teaching. It turns the computer from the desktop system with a keyboard and a monitor into a "spacecraft", equipped with speakers, microphone, headphones, joysticks and CDs.

1. What is multimedia?

software Multimedia Graphics Sound

Multimedia allows you to work on a computer with all kinds of information, and not just with text or ordinary drawings. Multimedia is digital information that has wider opportunities than other types of it.

b since sound and graphic information It is written in digital form, it can be copied without loss of quality.

b digital information can be compressed to a minimum for storage.

you can record a huge amount of information on the CD-ROM, and the CD-ROM itself takes very little space.

b interactive computer programsSending digital media systems are excellent learning tools.

If you buy a computer with built-in media media or install on your computer, then you need to understand the variety of media media, as well as get acquainted with existing ways to write and play. There are two main types of multimedia systems:

o. Reproduction systems. These systems, as a rule, include a multi-speed CD-ROM drive, a sound card, speakers and a video system with a relatively high resolution. There is also no presence of a decompression card operating with digital information.

o. Copyright systems. (Systems used to create multimedia system files). Copyright systems, as a rule, include components such as microphones and video cameras for recording sound and shooting video images. They are also high-speed, capable hard drives that can store and maintain large amounts of information required for digital video.

In the 1980s, a personal computer consisted of a microprocessor (CPU), keyboard, monitor, drive and printer. All you could do on the computer is to work with the text. People spent a lot of time, making up letters, producing financial calculations and viewing databases.

But now, when graphic user interfaces appeared as Windows95 / 98 (SE) / IU / NT / 2 K., And significantly more powerful personal computers have begun to appear applications that provide the ability to use animation effects, sound and video. At the end of 1980, people began to compose music on a computer, combining animation and sound, creating exciting multimedia presentations with sound and moving pictures. Equipment, however, was expensive, and the results often did not justify expectations. Windows3.1 and DOS did not have enough resources to support multimedia systems, so the pictures on the screen moved very slowly.

2. Multimedia and Windows 95/98 (SE) / I / NT / 2K/ XP.

Thanks to Windows, everything transformed. It supports funds to significantly improve work with multimedia.

b windows95 / 98 (SE) / I / NT / 2K. It is a 32-bit, multi-tasking, multi-threaded operating system. This means that Windows supports the execution of multiple tasks at the same time, playing multimedia presentations and user operation in the dialog mode.

b When installing Windows automatically determines the configuration of the multimedia devices.

b Windows Apps Support multimedia. You can create composite documents, i.e. Documents included sound, video, graphics, charts, pictures and other elements of various applications.

windows Supports Sony / Philips CD + and Kodak PhotoCD CD + and Kodak CD formats, and makes it easy to run programs and play discs from the CD-ROM device.

b. Video VideoTandart Windows is widely supported in the Computer Industry. Multimedia products developers can safely distribute their products, knowing that it will work under Windows.

b Multimedia products designed for Windows are usually high quality products, as Windows supports large video and 32-bit Windows architecture improves data passage.

windows supports Sony Visca interface. This means that in the applications you can use the so-called VCR buttons (VCR - English abbreviation from Video Cassette Recorder - VCR, i.e. buttons, functionally similar to the rewind, playback buttons and other on audio and video-reproducing devices) when playing laser disks.

b The quality of games in Windows is significantly improved due to the new software graphic interface.

b Windows supports many different standard industrial audio and video information on information compression when it is recorded to a file, as well as decompression during playback (so-called codec-devices). The codec reduces the amount of multimedia files and allows them to distribute them in various formats.

The most important means of multimedia in the last few years has become a video. The video accommodates an incredible amount of information that can be compressed before transferring it from one device to another, for example, from a video camera to a hard disk through a computer bus. The application of the compression technology of audio and video information allows you to expand the multimedia fund market.

3. Multimedia systems

Additional peripheral devices To the computer in the mid-80s there were drives, scanners, printers, and communication media modem. In the 90s appears sound cards, video cards, cD-ROM drives and high-speed communication products, thanks to which you can now contact the information service that transmits you multimedia by wires.

The minimum requirements for launching multimedia under Windows are listed below.

b Intel processor 80486 (Pentium is recommended for digital video applications).

b PCI bus for data transmission for disk controller and video card.

b Hard disk large volume (from 300 MB). For high-quality digital video systems requires gigabytes of memory.

b CD-ROM with a speed of not lower than 4 with sound adjustment on the front panel.

b Sound card, providing quantization frequency 11.025; 22.05 and 44.1-kHz for stereo sound. Also required multi-voice and multi-memory devices that can perceive several sources at the input, and at the output to present stereo.

b video equipment supporting high monitor permissions. Microsoft recommends that the best quality video use VESA or PCI video cards. Recently, AGP adapters have become popular.

b IBM-compatible analog port of the joystick.

b MIDI port supporting installed standards for input, output and data transfer. Some sound cards Contain MIDI synthesizers, but in the general case you connect to an external MIDI synthesizer, in appearance resembling the keyboard.

Midi. (Musical Instrument Digital Interface - Digital Musical Instrument Interface) is a standard for recording notes and related information related to music playing on an electronic music device. Real sound is not recorded.

The above components are required to play and write media tools. However, if you want to create multimedia clips yourself, you may need additional equipment.

4. Types and Multimedia Standards

Multimedia-information is stored as a special format files containing sound, video images, or in MIDI format files.

Audiomedia(sound media) is stored mainly in two formats, WAV and MIDI. Most WAV files require a lot of disk space, but they can play with any sound card. MIDI files occupy a significantly less disk space, but may only be played on MIDI compatible devices. Currently, almost all cards are able to play MIDI files.

Visual media - These are animated files and video files.

Animation. In Windows, if you have an appropriate application, you can create images moving across the screen. There is no standard format of the animation file, but many developers simultaneously develop the production of both animation tools and reproducing equipment. Animation may be accompanied by sound files of different formats.

Video. Video for Windows is a video standard for Windows. You can burn a movie from a camcorder or laser disk to a hard drive of the computer and save it as a file in AVI format or MPG. Compression is required only for high-quality video and its effective storage.

5. About sound multimedia

Applications for recording and playing sounds were one of the first known multimedia applications for a personal computer. By adding a sound card, you can record a message transmitted by voice, save it as a file on the disk, to transfer it to another computer, where it can also be reproduced. You can also record music and sound for computer presentations.

There are two ways of recording:

· Digital recordingWhen the actual sound waves are recorded and converted into digital data.

· Midi.-Z.apiceGenerally speaking, it is not a real sound, but recording clicks on the keys or other operations performed on synthesizers or MIDI-compatible electrical device. The MIDI file is an email equivalent game of piano.

6. Digital recording

The sound card converts the sound at the output into digital information by measuring sound thousands of times per second. The digital sound is stored in files with the extension WAV. When recording the sound, an analog-to-digital converter converts sound into digital data. When playing a sound, the digital-to-analog converter converts digital data into an analogue of the sound wave.

Sound It is vibrations that form a wave with appropriate amplitudes and a period, as shown in Fig. 1. The amplitude expresses the height of the wave, or the volume of the sound. The period is the distance between the two sound waves. Finally, the frequency shows the number of periods per second and is measured in Hertz. For example, one hundred periods per second is 100 Hz. A person can perceive the sound with a frequency of 20 to 20,000 Hz, and all the released sound-reproducing and sound recording equipment is designed for this frequency range.

Sound wave measurement

To record the sound and store it on a digital device such as your computer, a sound quantization is performed, i.e. Breaking the sound wave at certain time intervals. Sound wave shown in Fig. 2, was divided into 16 intervals. If we assume that the duration of the sound wave is equal to one second, then its quantization frequency is 16 Hz.

Quantization of the wave at a quantization frequency of 16 Hz

As a rule, such a low quantization frequency is not used. Even digital sound with a quantization frequency of 100 or 1000 Hz will not be recognized during playback. This is because the digital representation of the wave in this case is not smoothed. The filtering equipment smoothes the wave, however best way Receiving a high-quality digital record is to increase the frequency of quantization. It should be noted that it increases the amount of stored data, which will require more memory on the disk.

Multimedia standards correspond to three types of quantization frequency: 11.025; 22.05; 44.1 kHz. Quantization frequency depends on the sound recorded: 11.025 kHz is suitable for recording a voice, but the quantization rate of 44.1 or 48 kHz is required to obtain high-quality recording. However, the increase in quantization frequency leads to an increase in the size of the file and the required disk space for its storage. The formula for calculating the disk space will be shown below, but before you need to deal with one variable - the number of discharges (bits) used to store the quantization information.

Each interval contains information about a small temporary sound segment. The number of discharges for recording each interval determines the accuracy of the approximation of the sound wave, however, increases the size of the file in which the digital sound is stored. The 4-bit splitting at the intervals ensures the division of the amplitude of the sound wave vertically by 16 levels, and the 8-bit partition is 256 levels. For high-quality recording, a 16-bit splitting on amplitude intervals is required, which defines 65536 amplitude levels.

The preceding discussion concerned the smoothed sound wave, but the real wave is not smoothed - it consists of many different frequencies, which together create the voice of sound. The timbre is a unique sound inherent to the tool. For example, string oscillations and a resonator determine the sound of the violin (the unique sound of Stradivari violin is the result of the addition of valuable substances in its polishing). The violin produces a whole complex of sound waves, as shown in Fig. 3.

Now you see the importance of increasing the frequency of quantization and the discharge of the sound card when recording sound. You need to know not only the amplitude of each selected interval, but all that happens with a wave per unit of time. Increasing the frequency of quantization and bit of sound card provides high-quality sound recording, however, it should be remembered that this leads to a significant increase in the disk space required to store the recorded sound. Fortunately, if you record a voice, then there is no need to use a large quantization frequency and the discharge of the sound card.

Real sound waves have a very complex form and to obtain their high-quality digital presentation requires a high quantization frequency.

The following is a formula for calculating the required disk space for digital audio storage:

for a second

In tab. 1. The required disk space is given to storing the sound recording lasting one minute for each quantization frequency at a bit of 8 bits. The first line in the table corresponds to a low-quality voice record, and the last line - standards installed for digital audio components.

Sound File Storage Requirements

Bigness	Quantization frequency	Byte for storage
		0.66 MB / min
		1.32 MB / min
		2.646 MB / min
		5,292 MB / min

Note that the high frequency of quantization and discharge is not required if the sound was recorded and played on low-quality equipment. For example, a pocket microphone records the sound of much lower quality than the record at a quantization frequency of 44 kHz. If you have a high-quality entry, then for its playback, the high quality equipment is required, respectively.

7. Sound and Types of Sound Files

Sound - This is a physical natural phenomenon that spreads through air fluctuations and, therefore, we can say that we are dealing only with wave characteristics. Task of sound conversion in electronic view is the repetition of all of its most wave characteristics. But the electronic signal is not analog, and can be recorded by short discrete values. Let them have a small interval among themselves and practically imperceptible, at first glance for the human ear, but we should always keep in mind that we are dealing only with the emulation of the natural phenomenon called sound.
This entry is called pulse-code modulation and is a serial recording of discrete values. The discharge of the device calculated in the bits, indicates how many values \u200b\u200bsimultaneously in one recorded discrete, sound is taken. The greater the bit, the greater the sound corresponds to the original.

Any sound file can be represented so that you are most clear how the database. It has its own structure, the parameters of which is usually indicated at the beginning of the file. Then there is a structured list of values \u200b\u200bfor certain fields. Sometimes instead of values \u200b\u200bthere are formulas that allow you to reduce the size of the file. These files can read only the specialized programs in which the reading unit is laid.

RSM is decrypted as Pulse Code modulation, which is translated as a pulse-code. Files are quite rare with such an extension (I met only in the 3D Audio program). But RCM is fundamental to all sound files. I would not say that this is a very economical method for storing data on the disk, but I think that you will never definitely not go from this, and the volume of modern hard drives already allow you to not pay attention to a couple of dozen megabytes.

Reviews about the economical storage of audio data on the disk. If you meet this abbreviation, then know what you are dealing with a difference RCM. Based on this method It lies that quite justified the idea that calculations are much more cumbersome compared to the fact that you can simply specify the difference values.

Adaptive DPCM. Agree that when specifying simply difference values, there may be a problem with the fact that there are very small and very large values. As a result, whatever super-accurate measurements still have a distortion of reality. Therefore, in the adaptive method, the coefficient of scalability has been added.

The simplest repository of discrete data. I would say direct. One of the types of files of the RIFF family. In addition to the usual discrete values, the visibility, the number of channels and the values \u200b\u200bof the volume levels in the WAV may indicate many more parameters about which you are most likely not suspected - this is: Tags for synchronization positions, the total number of discrete values, the procedure for playing different parts of the sound File, as well as there is a place to place text information there.

Resource Interchange File Format. A unique storage system for any structured data.

This data storage technology stems from amiga systems. Interchange File Format. Almost the same as RIFF, only there are some nuances. Let's start with the fact that the Amiga system is one of the first in which they began to think about the program-sampler emulation of musical instruments. As a result, in this file, the sound is divided into two parts: what should appear first and the element of what goes beyond. As a result, it sounds started once, the second piece is repeated as many times as you need and the note may sound infinitely long.

The file stores a short sample of sound, which then can be used as a template for the tool. Simply put, stitched into a sample synthesizer.

AIF.or AIF.

Audio Interchange File Format. This format is distributed in Apple Macintosh and Silicon Graphics systems. Contains the combination of MOD and WAV.

AIFC or AIFF.-FROM

The same AIFF, only with the specified compression parameters (compression).

Again the same race for saving place. The structure of the file is much easier than in WAV, but the data encoding method is specified. Files very little "weigh", due to which they got quite widespread on the Internet. Most often you can meet the parameters? -LAW 8 kHz - mono. But there are 16-bit stereo files with frequencies 22050 and 44100 Hz. This sound format is designed to work with sound in Sun, Linux and FreeBCD working systems.

The file that stores the MIDI system messages installed on your computer or in the device.

The most scandalous format has recently. Many to explain the compression parameters that are used in it, compare it with JPEG for images. There are very many frills in the calculations, which they will not list, but the compression ratio of 10-12 times they said themselves. If they say that there is a quality, then I can say that there is a little bit. Specialists talk about the contour of the sound as a large lack of this format. Indeed, if you compare music with the image, then the meaning remained, and the small nuances gone. The quality of MP3 still causes a lot of disputes, but for "ordinary non-music" people, losses are not tangible.

A good alternative to MP3, except less common. There are also its drawbacks. Encoding the file in VQF - the process is much longer. In addition, very few free programs that allow you to work with this file format, which, in fact, has affected its distribution.

Eight-bit mono-format from the SoundBlaster family. You can find in a large number of old programs that use sound (not musical).

NSA.

The same as VOC (eight bits, mono), but only for Apple Macintosh.

Standard U-LAW format. 8 kHz, 8 bits, mono.

Real Audio or flow of audio data. A fairly common sound transmission system in real time via the Internet. Transmission rate of about 1 KB per second. The resulting sound has the following parameters: 8 or 16 bits and 8 or 11 kHz.

There are two types. One is the same AU for Sun and Next. The other is an 8-mibying mono-file for PC and poppies with different sampling frequency.

There are other types of sound files, but these are most likely files of various programs for creating and processing music. Basically, such files are read only by the program in which they were created.

8. Compression of audio data

Multimedia information consists of a huge number of digital data that needs to be stored in a compressed form. Windows includes the controls of the compression of audio and video images, which work with one or more decompression modules and are called codecs (from compression and decompression). A large number of program codecs are supplied with Windows. When you write down or play sound or video file, Windows automatically uses the codec.

Many sound and video cards have built-in hardware codecs. Windows first uses the hardware codec, since it is faster and does not load the processor. If the hardware codec is missing, then Windows applies software codecs. If she could not find a codec, an error message appears on the screen, since the compressed file cannot be unpaved.

Audio Compression Management Program (AUDIO Compression Manager, ACM) uses the following codecs for compression / decompression of audio data.

· Truespeech.Sodec.. Voice oriented codec developed by DSP Group. Use this codec only when compressing and transmitting on networks or telephone lines of files containing voice recording. Truespeech produces data compression not in real time, in turn, decompression is carried out real-time.

· Microsoft GSM Audio Codec. A codec that compresses the data of low-quality monochrome audio records in real time. Use this codec when recording voice messagesinserted into email messages (e-mail). To write voice messages, you can use the phonograph application.

· Microsoft CCITT G.711 A-LAW AND U-LAW CODEC. This codec provides compatibility of telephone standards in Europe and North America. It provides a 2: 1 data compression ratio.

· Microsoft ADPCM Codec.. This codec provides compression both in real, and not real-time, the latter is used by users of copyright multimedia systems. Audio files are better generated by a real-time codec scale.

· IMA ADPCM Codec.. This codec was recommended by Interactive Multimedia Association for use on different multimedia platforms. It compresses real-time and is similar to the Microsoft ADPCM codec.

· Microsoft PCM Converter.. This converter allows you to play a 16-bit sound on an 8-bit sound card. You can also use this codec in the case when you need to maintain a quantization frequency of 1 MHz for a card that supports another quantization frequency.

9. Digital Record Transformation Software

There are many codec programs designed specifically for file transformations with a digital record. The purpose of each such program is one - the compression of the sound file with the smallest loss of quality and the greatest degree of compression. Each of them has its own pros and cons: some compression quality is high, but the speed of this compression wishes the best, others are instantly encoded, but with a loss of quality, who wants to listen to the file with a favorite musical composition, which groachtitis, whistles and rustles like an old grandfather plate .

The most popular codec programs are shown below.

Voice

Software consists of four modules that can work on both the same computer and different.
The first module operating in the Windows environment is responsible for working with external equipment, it directly recording from the telephone (radio) line and playback to the telephone (radio) line of sound files.

Voice Program dialog box

The second software module responsible for compressing sound files uses standard WAV file compression algorithms to its operation. The compression algorithms used allow you to pack the incoming messages to the level of 4kb - 600 bytes per second. Compression algorithms can be promptly modified depending on the desired degree of compression and quality of sound.

The third software module is responsible for maintaining a database (adding conversations to the database and automatic removal from it as they are aging). In the database, the information is stored for a specified period of time, after which it is either archived or automatically deleted.

The last, the fourth software module is designed to work with the database: search for conversations, listening to, overwrite and manual removal.

All modules work in 32-bit Windows units. All software can simultaneously work both with each other and with other Windows applications.

Mpeg Encoder.

MPEG Encoder Program dialog box

One disadvantage of MPEG Encoder - takes a lot of time to compress the file with a digital record. On the processing of a sound file, about 3-5 minutes takes about 25-40 minutes. But expectations are worth it - the quality does not differ from the original.

The program consists only of one dialog box, which simplifies work. No additional knowledge in digital information transformations, etc., you specify the path to the outgoing file in the Source field and in the Target field, the final folder in which the compressed file in MP3 format (default) will be. Specify the frequency of quantization, quality parameters - stereo or mono and ... forward! Boldly press the ENCODE button.

Lamebatch

LameBatch is a simple shell written in order to simplify work with MP3 encoders, called Lame from Mark Taylor and the company. The shell is based on a simple core.

LameBatch Program Parameters dialog box

There are only two "Files" and "Settings" tabs, in the latter you specify all the compression parameters you need.

Basic chips:

lone only one window (without pop-ups directly to the encoder).

b customized coding settings for each file.

b The ability to change them for other files during the encoding of one.

b all kinds of information about the progress of the process.

• Check files for the permissibility of the format.

b Different queue sorting options.

b unparally prescribing tags.

look the opportunity to postpone work indefinitely.

b Various folder settings for results.

b checking overwriting and available space.

support Drag and Drop.

b embedded in context menu Explorer.

i turn off the machine at the end of the procedure.

The latest version for today is LameBatch 0.99c and released on October 25. When testing, LAME 3.35 was used. LameBatch is distributed as a freebie, therefore - no guarantees.

List of programs and their advantages, and shortcomings can be listed for a very long time. Program codecs have recently been developed a lot, it is worth connecting to the Internet, to type "PROGRAMS & ENCODE & MULTIMEDIA" in the "Programs & Encode & MultiMedia" search port line, how immediately you will receive a list of programs for processing sound and not only files.

Conclusion

We crushed a little about compressing sound files. For which it is necessary, it is not necessary to say especially, it is not worth mentioning that the widespread methods of compression of digital musical data 11-14 times have improperly push forward the program and "iron" musical industry, not to mention that with high-quality music now In the Internet problems, in general, no. You can find almost any composition. (In fact, of course, not any. Try to search for something nontrivial - Billy McCenzie, for example, or Bernie Mrsden, are unlikely to do anything. You can find mostly popular music or classics of the genre, and that far Not all.

From the moment of the start of its rapid development (about two years ago), the open technology of compression of musical (sound) information of qualitative changes to the compression technology has not been undergone. In other words, numerous fans of music have to put up with enough capacious files, because No shifts on this front is planned. Today's limits for compression without a significant loss of quality make up about 11-12 times from the original size of the music file. As is known, on a CD with a standard digitization frequency of 44,500 Hz (stereo, two bytes per amplitude value) can be fitted to 74 minutes of sound - about 10 MB to a minute.

With the average duration of the musical composition, 4 minutes have clean (uncompressed) sound 40 MB. Lot. Very much for the Internet. Having a modem with a speed of 33.6 KB / C and a full channel for download (i.e., ideally - 3.5 KB / s) 40 MB we will only get 4-5 hours (usually this figure in 1.5-2 times more).

By applying the compression of the music file without losing its main characteristics (stereo, frequency of sampling during digitization of 44 100 Hz, 2 bytes to the amplitude sample), you can achieve a decrease in size of 11-12 times. So instead of 40 MB will turn out only 3.8-3.9 MB. It is already quite acceptable. You can compress even more, but then we noticeably lose as: the differences from the original become heard and not even Melomanu. The limits referred here are 11 or 12 times are already selected and proven quality / size criteria for the entire short history of the use of squeezed files.

Literature

1. Tom Sheldon. "Windows 95 is easier than a simple" dialectic. Kiev. 1996

2. A. Chizhov. "Napster - Panacea for MP3 Melomanana" fantasy. 1999-2000

Posted on Allbest.ru.

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