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Ministry of Education of the Russian Federation

University of Control Systems and Radioelectronics

Multimedia

and its components

Programming essay

Compiled

checked

• • 1. What is multimedia? 3
  • 2. What is a CD-ROM? 3
  • 2.1. A bit of history. 4
  • 2.2. Parameters of CD-ROM drives. 4
  • 2.3. Transfer rate. 4
  • 2.4. Access time. five
  • 2.5. cache memory. 6
  • 3. Video cards. 6
  • 3.1. Monochrome adapter MDA. 6
  • 3.2. Color graphics adapter CGA. 7
  • 3.3. Advanced graphics editor EGA. 7
  • 3.4. VGA adapters. 7
  • 3.5. XGA and XGA-2 standards. 8
  • 3.6. SVGA adapters. 8
  • 4. Sound. 8
  • 4.1. 8- and 16-bit sound cards. 8
  • 4.2. Columns. 8
• 5. Perspectives. 10
• Tables. 11
• Literature. 13

1. What is multimedia?

The concept of multimedia covers a whole range of computer technologies related to audio, video and ways to store them. In the most general terms, it is the ability to combine image, sound and data. Basically, multimedia involves adding a sound card and a CD-ROM drive to your computer.

Microsoft created the Multimedia PC Marketing Council to establish standards for multimedia computers. This organization created several MPC standards, emblems and trademarks that were allowed to be used by manufacturers whose products meet the requirements of these standards. This made it possible to create joint hardware and software products in the field of multimedia for IBM-compatible systems.

Recently, the MPC Marketing Council transferred its authority to the Software Publishers Association's Multimedia PC Working Group. It included many council member organizations, and now it is the legislator of all MPC specifications. The first thing this did group, adopted the new MPC standards.

The Council developed the first two multimedia standards, called MPC Level 1 and MPC Level 2. In June 1995, after the creation of the Software Publishers Association (SPA) group, these standards were supplemented by a third - MPC Level 3. This standard defines the minimum requirements for multimedia -computer (see Table 1, page 11).

Next, let's take a closer look at the individual components (image, sound, and data) of multimedia.

1. What's happenedCD- ROM?

A CD-ROM is a read-only optical storage medium that can store up to 650 MB of data, which equates to approximately 333,000 pages of text or 74 minutes of high-quality audio, or a combination of both. A CD-ROM is very similar to regular audio CDs, and you can even try to play it on a regular audio player. However, you will only hear noise. Access to data stored on a CD-ROM is faster than data stored on floppy disks, but still significantly slower than on modern hard drives. TermCD- ROMrefers both to the CDs themselves and to devices (drives) in which information is read from the CD.

The scope of CD-ROMs is expanding very quickly: if in 1988 only a few dozen were recorded, today several thousand titles of a wide variety of thematic discs have been released - from statistical data on world agricultural production to educational games for preschoolers. Many small and large private firms and government organizations produce their own CDs of information of interest to experts in certain fields.

2.1. A bit of history.

In 1978, Sony and Philips joined forces to develop modern audio CDs. Philips had already developed a laser player by that time, and Sony had many years of research in the field of digital audio recording and production.

Sony insisted that the diameter of the CDs be equal to 12, and Philips proposed to reduce it.

In 1982, both firms published a standard that defined signal processing methods, how to record them, and the disk size - 4.72, which is still used today. The exact dimensions of the CD are as follows: outer diameter - 120 mm, diameter of the central hole - 15 mm, thickness - 1.2 mm. It is said that such dimensions were chosen because Beethoven's Ninth Symphony was completely placed on such a disc. The collaboration of these two firms in the 1980s led to the creation of additional standards regarding the use of technologies for recording computer data. Based on these standards, modern drives for working with compact discs were created. And if at the first stage engineers worked on how to choose the size of the disk for the greatest of symphonies, now programmers and publishers are thinking about how to squeeze more information into this small circle.

2.2. Parameters of CD-ROM drives.

The parameters given in the documentation for CD-ROM drives mainly characterize their performance.

The main characteristics of CD-ROM drives are the transfer rate and data access time, the availability of internal buffers and their capacity, and the type of interface used.

2.3. Transfer rate.

The data transfer rate determines the amount of data that the drive can read from the CD to the computer in one second. The basic unit of measurement for this parameter is the number of kilobytes of data transferred per second (KB/s). Obviously, this characteristic reflects the maximum reading speed of the drive. The faster the reading speed, the better, but remember that there are other important parameters.

In accordance with the standard recording format, 75 data blocks of 2048 useful bytes should be read every second. The data transfer rate in this case should be equal to 150 Kb / s. This is the standard baud rate for CD-DA devices, also called single speed. The term “single speed” means that CDs are recorded in constant line speed (CLV) format; while the speed of rotation of the disk is changed so that line speed remained constant. Since, unlike music CDs, data can be read from a CD-ROM disc at an arbitrary speed (as long as the speed is constant), it is quite possible to increase it. To date, drives are being produced in which information can be read at different speeds, multiples of the speed that is accepted for single-speed drives (see table 2, page 11).

2.4. Access time.

The data access time for CD-ROM drives is determined in the same way as for hard drives. It is equal to the delay between the receipt of the command and the moment the first bit of data is read. Access time is measured in milliseconds and its standard rating for 24x drives is approximately 95 ms. This refers to the average access time, since the actual access time depends on the location of the data on the disk. Obviously, when working on the inner tracks of the disk, the access time will be less than when reading information from the outer tracks. Therefore, in data sheets for drives, the average access time is given, which is defined as the average value when performing several random reads of data from the disk.

The shorter the access time, the better, especially in cases where data needs to be found and read quickly. Access time to data on CD-ROM is constantly decreasing. Note that this parameter is much worse for CD-ROM drives than for hard drives (100 - 200 ms for CD-ROMs and 8 ms for hard drives). Such a significant difference is due to fundamental differences in designs: hard drives use several heads and the range of their mechanical movement is less. CD-ROM drives use a single laser beam and it travels along the entire disc. In addition, the data on the CD is written along a spiral, and after moving the reading head to read this track, it is still necessary to wait for the laser beam to hit the area with the necessary data.

The data in table 3 (page 12) is typical for high-end devices. Within each category of drives (with the same data transfer rate) there may be devices with a higher or lower access time value.

2.5. cache memory.

Many CD-ROM drives have built-in buffers, or caches. These buffers are memory chips installed on the drive board for recording read data, which allows you to transfer large amounts of data to a computer in one call. Typically, the buffer capacity is 256 KB, although there are models with both larger and smaller sizes (the more the better!). As a rule, faster devices have larger buffers. This is done for higher data rates. The recommended internal buffer capacity is at least 512 KB, which is the standard value for most twenty-four speed devices.

2. Video cards.

The video card generates monitor control signals. With the advent of the PS / 2 family of computers in 1987, IBM introduced new standards for video systems, which almost immediately replaced the old ones. Most video adapters support at least one of the following standards:

MDA(Monochrome Display Adapter);

CGA (Color Graphics Adapter);

EGA (Enhanced Graphics Adapter);

VGA (Video Graphics Array);

SVGA (Super VGA);

XGA (eXtended Graphics Array).

All programs designed for IBM-compatible computers are designed for these standards. For example, within the Super VGA (SVGA) standard, different manufacturers offer different image formats, but 1024768 is the standard for rich image applications.

3.1. Monochrome adapter MDA.

The first and simplest video adapter was a monochrome adapter conforming to the MDA specification. On its board, in addition to the display control device itself, there was also a printer control device. The MDA video adapter provided only the display of text (characters) at a horizontal resolution of 720 pixels, and a vertical resolution of 350 pixels (720350). It was a character output oriented system; she could not display arbitrary graphic pictures.

3.2. Color graphics adapter CGA.

For many years, the CGA color graphics adapter was the most common video adapter, although now its capabilities are very far from perfect. This adapter had two main groups of operating modes - alphanumeric, or symbolic (alphanumeric - A/ N), And graphic with addressing of all points (all point addressable - AD). There are two character modes: 25 lines of 40 characters each and 25 lines of 80 characters (both operate with sixteen colors). In both graphic and character modes, 88-pixel matrices are used to form characters. There are also two graphic modes: color with medium resolution (320200 pixels, 4 colors in one palette out of 16 possible) and black and white with high resolution (640200 pixels).

One of the disadvantages of CGA video adapters is the appearance of flickering and “snow” on the screens of some models. flicker manifests itself in the fact that when the text moves around the screen (for example, when adding a line), the characters begin to “wink”. Snow are random flashing dots on the screen.

3.3. Advanced graphics editor EGA.

The advanced graphics editor EGA, which was discontinued with the introduction of PS/2 computers, consisted of a graphics card, an image memory expansion card, a set of image memory modules, and a high-resolution color monitor. One of the advantages of EGA was the ability to build a system on a modular basis. Because the graphics card worked with any of the IBM monitors, it could be used with both monochrome monitors and early-resolution color monitors, as well as higher-resolution color monitors.

3.4. VGA adapters.

In April 1987, coinciding with the release of the PS/2 family of computers, IBM introduced the VGA (video graphics matrix) specification, which soon became the accepted standard for PC display systems. In fact, on the same day, IBM released another specification for low resolution MCGA display systems and launched the IBM 8514 high resolution video adapter.

3.5. XGA and XGA-2 standards.

At the end of October 1990, IBM announced the release of a video adapter XGA display Adapter/ A for the PS / 2 system, and in September 1992 - the release of XGA-2. Both devices are high quality 32-bit adapters with the ability to transfer bus control to them (bus master) designed for computers with an MCA bus. Developed as a new form of VGA, they provide higher resolution, more colors and significantly higher performance.

3.6. SVGA adapters.

With the advent of the XGA and 8514/A video adapters, IBM's competitors decided not to copy these VGA resolutions, but to start producing cheaper adapters with a resolution higher than the resolution of IBM products. These video adapters formed the category Super VGA, or SVGA.

The capabilities of SVGA are wider than those of VGA boards. At first, SVGA was not a standard. This term meant many different developments from various companies, the requirements for the parameters of which were stricter than the requirements for VGA.

4. Sound.

4.1. 8- and 16-bit sound cards.

The first MPC standard called for "8-bit" audio. This does not mean that sound cards had to be inserted into an 8-bit expansion slot. Bit depth characterizes the number of bits used for the digital representation of each sample. With eight bits, the number of discrete levels of the audio signal is 256, and if you use 16 bits, then their number reaches 65,536 (in this case, of course, the sound quality much is improving). 8-bit representation is sufficient for recording and playback speeches, but music requires 16 bits.

4.2. Columns.

Successful commercial presentations, multimedia and MIDI work require high-quality stereo speakers. Standard speakers are too big for a desktop.

Often sound cards do not provide enough power for the speakers. Even 4 W (like most sound cards) is not enough to “rock” high-end speakers. In addition, ordinary columns create magnetic fields and, when placed near a monitor, may distort the image on the screen. The same fields can corrupt the information recorded on the diskette.

To solve these problems, speakers for computer systems should be small and with high efficiency. They must be provided with magnetic protection, for example, in the form of ferromagnetic screens in the housing or electrical compensation of magnetic fields.

Dozens of speaker models are produced today, from cheap miniature devices from Sony, Koss and LabTech to large self-powered units such as Bose and Altec Lansing. To assess the quality of the speaker, you need to have an idea about its parameters.

frequency response (frequency response). This parameter represents the frequency band reproduced by the speaker. The most logical range would be from 20 Hz to 20 kHz - it corresponds to the frequencies that the human ear perceives, but no speaker can perfectly reproduce the sounds of this entire range. Very few people hear sounds above 18 kHz. The highest quality speaker reproduces sounds in the frequency range from 30 Hz to 23 kHz, while the cheaper models are limited to sound in the range from 100 Hz to 20 kHz. The frequency response is the most subjective parameter, since the same, from this point of view, speakers can sound completely different.

Nonlinear distortion (TDH - Total Harmonic Distortion). This parameter determines the level of distortion and noise that occurs during signal amplification. Simply put, distortion is the difference between what is fed into the speaker sound signal and audible sound. The amount of distortion is measured as a percentage, and a distortion level of 0.1% is considered acceptable. For high-quality equipment, a distortion level of 0.05% is considered the standard. Some speakers have distortions as high as 10%, and for headphones - 2%.

Power. This parameter is usually expressed in watts per channel and indicates the output electrical power supplied to the speakers. Many sound cards have built-in amplifiers with up to 8 watts per channel (typically 4 watts). Sometimes this power is not enough to reproduce all the shades of sound, so many speakers have built-in amplifiers. Such speakers can be switched to amplify the signal coming from the sound card.

3. Perspectives.

So, the world is clearly experiencing a multimedia boom. At such a pace of development, when new directions are emerging, and others that seemed very promising suddenly become uncompetitive, it is difficult to compile even reviews: their conclusions may become inaccurate or even outdated after a very short time. Forecasts of the further development of multimedia systems are all the more unreliable. Multimedia significantly increases the quantity and improves the quality of information that can be stored in digital form and transmitted in the “man-machine” system.

Tables.

Table 1. Media standards.

CPU			75MHz Pentium
HDD
floppy drive	3.5-inch 1.44 MB	3.5-inch 1.44 MB	3.5-inch 1.44 MB
Storage device	Single speed	double speed	quadruple speed
VGA adapter resolution	640480,	640480, 65536 colors	640480, 65536 colors
Ports I/O		Serial, Parallel, Game, MIDI	Serial, Parallel, Game, MIDI
Software	Microsoft Windows 3.1	Microsoft Windows 3.1	Microsoft Windows 3.1
Acceptance date

Table 2. Data transfer rates in CD-ROM drives

Drive type	Data transfer rate, bytes/s	Data transfer rate, KB/s
Single speed (1x)
Two speed (2x)
Three speed (3x)
Four speed (4x)
Six speed (6x)
Eight speed (8x)
Ten speed (10x)
Twelve-speed (12x)
Sixteen speed (16x)
Eighteen speed (18x)
Thirty-two speed (32x)
100 speed (100x)
	1 843 200 - 3 686 400

Table 3. Standard access times for data in CD-ROM drives

Drive type	Data access time, ms
Single speed (1x)
Two speed (2x)
Three speed (3x)
Four speed (4x)
Six speed (6x)
Eight speed (8x)
Ten speed (10x)
Twelve-speed (12x)
Sixteen speed (16x)
Eighteen speed (18x)
Twenty-four speed (24x)
Thirty-two speed (32x)
100 speed (100x)

Literature.

Scott Mueller, Craig Zecker. PC upgrade and repair. - M.: Williams Publishing House, 1999. - 990 pages.

S. Novoseltsev. Multimedia - synthesis of three elements//Computer Press. - 1991, No. 8. - pp. 9-21.

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Today, the term "multimedia" is quite understandable - it is a combination of well-known ways of transmitting information, such as images, speech, writing, gestures. This combination is, as a rule, deeply thought out, assembled from different elements that complement each other to create a common intelligible picture. All this can be observed on almost every information resource, for example, a news feed with photos or attached videos. The project can be both well-formed, when the story is built by the creator and goes linearly, and there are also several other types, such as interactivity and transmedia, which make the plot non-linear and create opportunities for the user to create their own script. All this is additional advanced features to create more interesting content, to which the user will want to return again and again.

The main thing in the concept of "multimedia" is that the combination of basic media elements builds on the basis of a computer or any digital technologies. It follows that the standard components of multimedia have a more extended meaning Vaughan, T. Multimedia: Making it work (7th ed.). New Delhi: Mac-Graw Hill. 2008.pp.1-3, 25-40, 53-60:

1. Text. Written language is the most common way to convey information, being one of the main components of multimedia. Initially it was printed media mass media, such as books and newspapers that used different fonts to display letters, numbers, and special characters. Regardless, multimedia products include photos, audio, and video, but text can be the most common type of data found in multimedia applications. In addition, text also provides opportunities to extend the traditional power of writing by linking it to other media, making it interactive.

a. Static text. In static text, words are laid out to fit well into the graphical environment. Words are embedded in graphs in the same way that graphs and explanations are on the pages of a book, that is, the information is well thought out and it is possible not only to see photos, but also to read textual information Kindersley, P. (1996). Multimedia: The complete guide. New York: DC..

b. Hypertext. The hypertext file system consists of nodes. It contains text and links between nodes that define paths that the user can use to access the text in an inconsistent manner. Links represent associations of meaning and can be thought of as cross-references. This structure is created by the system author, although in more complex hypertext systems the user can define their own paths. Hypertext provides the user with flexibility and choice as they move through the material. Well-formatted sentences and paragraphs, spacing and punctuation also affect the readability of the text.

2. Sound. Sound is the most sensual element of multimedia: it is direct speech in any language, from whispers to screams; it is something that can provide the enjoyment of listening to music, create a striking background special effect or mood; this is something that can create an artistic image, adding the effect of the presence of the narrator to a text site; help you learn how to pronounce a word in another language. The sound pressure level is measured in decibels, which should be within the limits of sufficient perception of the sound volume by the human ear.

a. Digital interface of musical instruments (Musical Instrument Digital Identifier - MIDI). MIDI is a communication standard developed in the early 1980s for electronic musical instruments and computers. It is a shorthand representation of music stored in numerical form. MIDI is the fastest, easiest and most flexible tool for scoring multimedia projects. Its quality depends on the quality of musical instruments and the capabilities of the sound system. Vaughan, T. Multimedia: Making it work (7th ed.). New Delhi: Mac-Graw Hill. 2008.pp.106-120

b. Digitized and recorded sound (Digital Audio). Digitized audio is a sample in which each fraction of a second corresponds to an audio sample stored as digital information in bits and bytes. The quality of this digital recording depends on how often samples are taken (sampling rate) and how many numbers are used to represent the value of each sample (bit depth, sample size, resolution). The more often a sample is taken and the more data is stored about it, the better the resolution and quality of the captured sound when it is played back. Quality digital sound also depends on the quality of the original audio source, the capture devices that support the software, and the ability to reproduce the environment.

3. Image. It is an important component of multimedia, since it is known that a person receives most of the information about the world through vision, and the image is always what visualizes the text Dvorko, N. I. Fundamentals of directing multimedia programs. St. Petersburg State Unitary Enterprise, 2005. ISBN 5-7621-0330-7. - from. 73-80. Images are generated by the computer in two ways, as bitmaps and also as vector images Vaughan, T. Multimedia: Making it work (7th ed.). New Delhi: Mac-Graw Hill. 2008.pp.70-81.

a. Raster or Bitmap images. The most common storage form for images on a computer is a raster. It's a simple matrix of tiny dots called pixels that form a bitmap image. Each pixel is made up of two or more colors. Color depth is determined by the amount of data in bits used to determine the number of colors, for example, one bit means two colors, four bits means sixteen colors, eight bits already show 256 colors, 16 bits gives 65536 colors, and so on. Depending on hardware capabilities, each dot can display more than two million colors. A large image means that the picture will look more real than what the eye sees or the original product. This means that the proportions, size, color and texture must be as accurate as possible.

b. Vector image. The creation of such images is based on the drawing of elements or objects, such as lines, rectangles, circles, and so on. The advantage of a vector image is that the amount of data required to represent the image is relatively small and therefore does not require a large amount of storage space. An image consists of a set of commands that are executed when needed. A bitmap image requires a certain number of pixels to produce the appropriate height, width, and color depth, while a vector image is based on a relatively limited number of drawing commands. The degradation in the quality of vector images is the limited level of detail that can be represented in a picture. Compression is used to reduce the file size of an image, which is useful for storing a large number of images and increasing the transmission speed of images. The compression formats used for this purpose are GIF, TIFF, and JPEG Hillman, D. Multimedia: Technology and applications. New Delhi: Galgotia. 1998..

4. Video. It is defined as the display of recorded real events on a TV screen or computer monitor. Embedding video in multimedia applications is a powerful tool for conveying information. It may include personality elements that other media lack, such as displaying the personality of the presenter. Video can be classified into two types, analog video and digital video.

a. Analog video (Analog Video). This type of video data is stored on any non-computer media such as video cassettes, laser discs, films, etc. They are divided into two types, composite and component analog videos:

i. Composite video (Composite Analog Video) has all video components, including brightness, color, and timing, combined into a single signal. Due to compositing or combining video components, video quality loses color, sharpness, and performance loss as a result. Loss of performance means loss of quality when copying for editing or other purposes. This recording format was used to record videos on magnetic tape such as Betamax and VHS. Composite video is also susceptible to quality loss from one generation to the next.

ii. Component analog video (Component Analog Video) is considered more advanced than composite. It takes the various components of a video, such as color, brightness, and timing, and breaks them down into individual signals. S-VHS and HI-8 are examples of this type of analog video, in which color and brightness are stored on one track and information on another. In the early 1980s, Sony released a new portable, professional video format that stored signals on three separate tracks.

b. Digital Video is the most interesting multimedia medium and is a powerful tool for attracting computer users closer to the real world. Digital video requires a lot of storage space, because if a high-quality still color image on a computer screen requires one megabyte or more of storage, then the image must be changed at least thirty times per second, and storage space requires thirty megabytes for one second of video. Thus, the more times the picture is replaced, the more better quality video. Video requires high bandwidth to transmit data in a network environment. There are digital video compression schemes for this. There are video compression standards like MPEG, JPEG, Cinepak and Sorenson. In addition to video compression, there are streaming technologies such as Adobe Flash, Microsoft Windows Media, QuickTime, and Real Player that provide acceptable video playback at low Internet bandwidth. QuickTime and Real Video are the most commonly used for widespread. Digital video formats can be divided into two categories, composite video and component video.

i. Composite digital recording formats encode information in binary (0 and 1). It retains some of the weaknesses of analog composite video, such as image color and resolution, as well as quality loss when making copies.

ii. The component digital format is uncompressed and has very high image quality, making it very expensive.

iii. Video can in many areas. Video recordings can improve the understanding of the subject when relevant to the explanation. For example, if we want to show dance steps used in different cultures, then a video will reflect this more simply and effectively. Vaughan, T. Multimedia: Making it work (7th ed.). New Delhi: Mac-Graw Hill. 2008.pp.165-170

Today, multimedia is developing very rapidly in the field information technologies. The ability of computers to handle various types of media makes them suitable for a wide range of applications, and most importantly, more and more people have the opportunity not only to look at various multimedia projects, but also to create them themselves.

255. Horizontally. 3. A multimedia component representing moving images through sequential frame changes. 4. Link from one email information object to another (for example, from a word to an interpretation of its meaning). 6. A multimedia product, which is a sequence of slides designed in the same graphic style, containing text, pictures, photographs, animation, video and sound. 9. Technology that provides simultaneous work with sound, videos, animations, static images and texts in an interactive (dialogue) mode. 11. The process of converting information from a continuous form of representation to a discrete one. 12. A special blank of several slides, in which there are places for entering certain information objects. Vertically. 1. The form of organization of textual material, in which its units are presented not in a linear sequence, but as a system of possible transitions explicitly specified with the help of hyperlinks, links between them. 2. Component of multimedia; air vibrations. 5. Computer simulation of movement by changing (and redrawing) the shape of objects or displaying successive images with phases of movement. 7. Sound card. 8. A technology in which, in addition to text objects, graphic and sound objects act as hyperlinks. 10. Allows you to maintain a single graphic style of the presentation (color scheme, background image, formatting options for text and other objects).

Sound is the most expressive element of multimedia. The world of sounds surrounds a person constantly. We hear the sound of the surf, the rustle of leaves, the roar of waterfalls, the singing of birds, the cries of animals, the voices of people. All these are the sounds of our world.

The history of this element of information for a person is as ancient as the previous ones (text, image). Initially, man created devices with which he tried to reproduce natural sounds for his practical purposes, in particular for hunting. Then the sounds in his head began to take shape in a certain sequence that he wanted to keep. The first musical instruments appeared (one of the oldest is the Chinese krin). Gradually, the process of forming a language was going on, in which it would be possible to record and thereby preserve the born melodies for a long time. The first attempts to develop such a "musical alphabet" were made in ancient Egypt and Mesopotamia. And in the form in which we know it now (in the form of musical notation), the system of fixing music developed by the 17th century. Its foundations were laid by Guido d'Arezzo.

At the same time, sound recording and storage systems were being improved. Man has learned to save and reproduce not only music, but also any surrounding sounds. Sound was first recorded in 1877 on the phonograph invented by Thomas Edison. The record looked like depressions on a paper sheet mounted on a rotating cylinder. Edison was the first to teach his car to say “hello” loudly into a microphone. This word was heard when a needle connected to a microphone repeated the recording made on paper. The mechanical-acoustic method of sound recording lasted until the 1920s, until electrical systems were invented. Two revolutionary inventions also contributed to the practical application of sound recording:

the invention of the plastic magnetic tape in 1935;

· the rapid development of microelectronics in the 60s.

Rapid development computer science gave this process a new impetus for development. The world of sounds was gradually connected with the digital world.

In sound cards, there are two main methods of sound synthesis:

wavetable synthesis(WaveTable, WT), based on the playback of samples - digitally pre-recorded sounds of real instruments. Most sound cards contain a built-in set of instrument sounds recorded in ROM, some cards allow the use of recordings that are additionally loaded into RAM. To obtain a sound of the desired height, a change in the playback speed of the recording is used, complex synthesizers use parallel playback of different samples to play each note and additional sound processing (modulation, filtering).

Advantages: The realism of the sound of classical instruments, the ease of obtaining sound.

disadvantages: a rigid set of pre-prepared timbres, many of whose parameters cannot be changed in real time, large amounts of memory for samples (sometimes up to hundreds of KB per instrument), unequal sounding of different synthesizer models due to different sets of standard instruments.

frequency modulation(Frequency Modulation, FM) - synthesis based on the use of several signal generators with mutual modulation. Each generator is controlled by a circuit that regulates the frequency and amplitude of the signal and is the basic unit of synthesis - the operator. Sound cards use two-operator (OPL2) and four-operator (OPL3) synthesis. The operator connection scheme (algorithm) and the parameters of each operator (frequency, amplitude and the law of their change in time) determine the sound timbre. The number of operators and their control scheme set the maximum number of synthesized timbres.

Advantages: no need to pre-record the sounds of instruments and store them in ROM, a wide variety of sounds obtained, it is easy to repeat the timbre on various boards with compatible synthesizers.

disadvantages: it is difficult to provide a sufficiently harmonious timbre in the entire sound range, the imitation of the sound of real instruments is extremely rough, it is difficult to organize fine control of operators, which is why sound cards use a simplified circuit with a small range of possible sounds.

If the composition needs the sound of real instruments, the wave synthesis method is better suited, but for creating new timbres, the frequency modulation method is more convenient, although the capabilities of FM synthesizers on sound cards are quite limited.

Often the concept of "multimedia" (generally, a very controversial term) is described as the 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 different options for displaying information by graphic means that belong to one environment (and not to "many environments", or multimedia), namely - to the visual environment.

So, by and large, it is possible to talk about multimedia only when an audio component is added to the means of influencing the organs of vision. Of course, computer systems are currently known that can also affect human tactile perception and even create smells inherent in certain visual objects, but so far these applications either have highly specialized applications or are in their infancy. Therefore, it can be argued that today's multimedia technologies are technologies that are aimed at transmitting information, affecting mainly two channels of perception - vision and hearing.

Since the descriptions of multimedia technologies on print pages unfairly pay much less attention to the audio component than to the technologies for transferring graphic objects, we decided to fill this gap and asked one of the leading Russian experts in the field of digital sound recording to tell us about how an audio sequence for multimedia content is created - Sergei Titov.

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

Sergei Titov: In principle, we perceive about 80% of all information about the outside world with the help of vision and less than 20% - with the help of hearing. However, it is impossible to do without these 20%. There are quite a few multimedia applications where sound comes first and it is he who sets the tone for the whole work. For example, most often a video clip is made for a specific song, rather than a song is written under the video. Therefore, in the expression "audiovisual series" it is the word "audio" that comes first.

If we talk about the sound component of multimedia, then there are two aspects: from the point of view of the consumer and from the point of view of the creator. Apparently, it is the aspect of creating multimedia content that is of interest for a computer magazine, since it is created using computer technology.

Speaking about the means of creating audio content, it should be noted that the production process requires a fundamentally higher resolution when recording files than for the stage of consumption, and, accordingly, higher quality equipment is needed.

Here you can draw an analogy with graphics: a designer can subsequently submit a low-resolution image, for example, for publication on the Internet, and at the same time discard some of the information, but the development and editing process is inevitably carried out taking into account all available information, moreover, decomposed into layers. The same thing happens when working with sound. Therefore, even if we are talking about an amateur studio, then, at a minimum, we should talk about semi-professional level equipment.

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

KP: How does the process of creating a sound row take place?

S.T.: Any sound picture is created from some constituent elements. Just as a DJ in a disco operates with a certain set of initial components, from which he builds a continuous program, so a person engaged in scoring something has some initial materials that he edits and brings together into a finished picture. If we are talking about music in its purest form, then at first the task is to fix these elements, and then collect them into a single picture. This, in general, is called convergence.

If we are talking about voicing some video sequence (in fact, here we can talk about multimedia content), then you need to collect the elements that make up sound accompaniment, and then “attach” them to the picture, edit these elements and bring them into mutual correspondence; at the same time, the individual elements in question must be arranged in a form convenient for work.

Computer programs create an interface where there are the same tracks and a mixer with a ruler. Under each of these rulers is its own element, which is subjected to one or another modification. Thus, we create a certain synthesized sound field, operating with the existing elements, and since this task is basically creative, we should be able to modify these elements using various types of processing - from simple editing (cutting, sorting, pasting) to complex , when individual elements can lengthen or shorten, when you can change the nature of the sound of each signal.

KP: What software do you need to do this job, and what special computer hardware is needed?

S.T.: Dedicated computer hardware is essentially just an I/O board, although other workstation systems have certain requirements, of course. Software for organizing the process of sound recording and editing exists in huge number: from cheap amateur to semi-professional and highly professional systems. Most of these programs have a plug-in architecture, require high performance from the computer and sufficiently powerful disk memory subsystems. The fact is that to solve multimedia problems for the purposes of production, and not the reproduction of content, machines with a large amount of RAM and a powerful processor are required. The most significant parameter here is not so much the high power of the processor as the good balance of the machine in terms of disk subsystems. The latter are typically SCSI devices, which are preferred when dealing with data streams that must not be interrupted. Therefore, IDE interfaces are practically not used. An IDE can have a very high burst transfer rate but a low sustain transfer rate.

At the same time, the IDE interface provides that the disk can give data, accumulating them in a buffer, and then pumping it out of the buffer. SCSI works differently, and even if the burst rate is low, the streaming rate will still be high.

It should also be noted that the above tasks require very large amounts of disk space. I will give a simple example - a 24-bit mono file, even at low sampling rates, such as 44.1 kHz, takes 7.5 MB per track per minute.

KP: Is there some technology to store this data more compactly?

S.T.: It's linear PCM (Pulse Code Modulation), which you can't compress. It can then be compressed into MP3, for example, but not at the production stage, but at the distribution stage. At the production stage, we are required to work with linear, uncompressed signals. Again, I will give an analogy with Photoshop. In order to build a graphic composition, the designer must have a complete understanding of what is stored in each layer, have access to each layer and adjust it separately. All this leads to the fact that the Photoshop PSD format takes up a decent amount, but allows you to go back at any time and make corrections to each layer without affecting all the others. At the moment when the picture is fully built, it can be presented in a different format, compressed with or without loss, but, I repeat, only when the production stage is completely completed. The same thing happens with sound - you can reduce the sound composition only if you have complete information about all the components of the signal.

As I said before, to create a sound picture, you need a source library that is appropriate for the task you are working on. Therefore, the video producer needs a lot of pre-recorded noises and effects, and the DJ needs the so-called loops (repetitive elements typical of dance music). All this material must be stored in the form of files that are understandable for the corresponding program that works with them. Further, an acoustic system is needed in order to control all this, and the program, accordingly, must make it possible to manipulate this source material, which, in fact, is the creative part of the process. Taking advantage computer system as a means of input-output and a program as an instrument, the user, in accordance with his inner instinct, edits the source material: increases or decreases the volume of individual elements, changes the timbre. As a result of the mixing process, the sound engineer must obtain a balanced sound picture that would have a certain aesthetic value. As you can see, the analogy with graphics is noticeable even at the terminological level. And whether this picture will be worth something depends entirely on the experience, taste, talent of this sound engineer (of course, subject to the availability of high-quality equipment).

KP: So far, we have been referring to a purely sound picture, however, speaking of multimedia, it is necessary to consider what means exist to bring together sound and image. What is needed for this?

S.T.: Of course, you need a video I / O card, for example, having an MPEG or Quick time output format (if we talk about multimedia, then Quick time will be more convenient).

KP: I believe it would be interesting to consider a number of practical tasks for voicing a video sequence and, using specific examples, find out what equipment and what software is required for tasks of various levels of complexity. We could start with an analysis of options for creating an inexpensive presentation film ...

For example, let's consider the following case: there is a video film shot by an amateur camera, and lines and dialogues have already been recorded on the microphone of this camera. Now we need to make an attractive presentation film with semi-professional voice acting based on this. What will be needed for this?

S.T.: If we are faced with the task of achieving a certain perception of sound material (whether it be an amateur film), a lot needs to be added to the source material: we need sound effects, background music, the so-called background noises (from the English background - background, background) and so on. Therefore, in any case, it becomes necessary to have several tracks playing at the same time, that is, to read several files at the same time. At the same time, we should be able to adjust the nature of the timbre of these files during the production process and edit them (lengthen, shorten, etc.).

It is important to note that the system should allow for experimentation so that the user can see if a given effect sounds right for a given location. The system should also allow sound effects to be precisely matched to the sound context, panning (in stereo sound) and so on…

KP: Well, the task is clear, and the requirements for the equipment are clear ... Now I would like to get an idea of ​​what specific equipment and what software can be recommended to solve such a problem and approximately how much it will cost the user.

S.T.: In principle, we need some kind of video editor, but this, as I understand it, is a separate issue, and today we should concentrate on the sound component. In any case, in the task that you described above, the sound sequence is subordinate to the video sequence. Therefore, we will assume that we have a video sequence, and we will not analyze how it is edited. We consider the original version, when there is a final video sequence and a rough audio sequence. In this draft audio sequence, you need to cross out some lines, replace some with new ones, and so on. It doesn't matter if we are talking about a presentation film or an amateur game - we will 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 microphone of the video camera, will sound, as they say, unconvincing.

KP: And where else can you get these sounds, if not from real filmed events?

S.T.: This is a whole direction called sound design, which consists in creating such sounds that, when reproduced, would give a convincing sound picture, taking into account the characteristics of the perception of sounds by the viewer. In addition, there is a so-called dramatic underlining in the picture of certain sounds that actually sound different. Of course, if we are talking about amateur cinema and semi-professional dubbing, then some opportunities turn out to be curtailed, but the tasks before us in this case are the same as for professionals.

In any case, in addition to editing the draft, you need to add some special effects.

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

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

KP: I would like to hear what Nuendo allows you to do?

S.T.: Nuendo is a software package that has a plug-in architecture and is designed to solve the problems of audio production, and it is focused specifically on the tasks of creating "audio for video", that is, one might say, it is designed specifically for solving multimedia problems. The program works with sound and image at the same time, while the image for it is a secondary component. Nuendo runs on Windows NT, Windows 98, and BE OS. This program costs $887.

The program provides the ability to view a video image decomposed in time, and a multi-track system for editing and mixing the sound picture.

A feature of the software package is its flexibility, and you can work on a wide range of inexpensive hardware. It is widely believed that serious systems run only on hardware with specialized DSP coprocessors. Nuendo software proves otherwise, as it not only provides tools for professional audio production, but also does not require specialized hardware and special coprocessors for its needs.

Nuendo provides 200 mix tracks, supports surround sound in a way that makes many systems pale in comparison to Nuendo.

Nuendo provides high-quality real-time processing on the same processor as the workstation itself. Of course, the processing speed will depend on the chosen workstation, but the advantage of the program lies in the fact that it adapts to different processor capacities. A few years ago, serious audio processing was unthinkable without a DSP. But today, desktop computers have their own processors powerful enough to handle real-time processing tasks. Obviously, the ability to use a conventional computer to solve specific problems without the need for DSP coprocessors adds flexibility to the system.

Nuendo is an object-oriented system (that is, a system that operates with metaphoric objects: remote control, indicator, track, etc.), which allows you to easily and fully edit audio files in projects of varying complexity, providing a very convenient and thoughtful interface. Drag-and-drop tools are available for a variety of tasks and are especially heavily used when handling crossfades.

An important feature of the program is the almost unlimited system of Undo & Redo editing functions. Nuendo provides more than just Undo & Redo operations: each of the audio segments has its own edit history, and the system is organized in such a way that after several hundred Undo & Redo changes, the maximum file size required to store a segment never more than doubles compared to original volume.

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

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

S.T.: We listen to the soundtrack that we already have and see what information we need to remove and what we need to edit.

KP: If we're talking about an amateur film, how many tracks might we need?

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

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

S.T.: Think for yourself: one track is occupied by drafts, the second - by special effects, the third - by off-screen music, and this is not only music, but also dialogues, comments, and so on. When all this is put together, it turns out just such a number of tracks.

Also, 16 or even 24 tracks is a relatively small number. In professional films, their number can exceed well over a hundred.

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

S.T.: An affordable option that I would suggest considering is a combination of the DIGI-001 board and Pro Tools 5 LE. This option is significantly better in terms of the quality of the I / O board and somewhat poorer in software.

Currently, there is a version for Mac OS and a version for Windows NT is coming out just the other day (I hope that by the time this magazine is published, the Windows version of this program will also appear in Russia). The hardware for Windows and Mac OS is exactly the same.

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

S.T.: The misconception that a PC sound station costs less than a Macintosh solution is a common one. But the opinion that there are cheap PC-based stations and expensive Macintosh-based stations is also wrong. There are specific systems to solve specific tasks, and the fact is that sometimes it is very difficult to build a PC-based system for solving problems related to the creation of multimedia content, since it is very difficult to assemble a machine from a random set of cheap IBM-compatible parts that would give optimal performance ...

Regardless of the type of workstation that will work in the system, DIGI 001 will provide much more features than SoundBlaster, and the board costs only $ 995 together with Pro Tools 5.0 LE "mathematics", that is, about the same amount how much and the previous solution with the cheapest SoundBlaster.

At the same time, if the Nuendo plus SoundBlaster solution is an option in which the possibilities are limited by a cheap board, and the software has very broad capabilities, then the solution based on DIGI 001 plus Pro Tools 5.0 LE is a much more powerful board, and the software is somewhat more modest in terms of its capabilities than Nuendo. To make it clear what we are talking about, we list the advantages of this solution from the point of view of the I / O board. DIGI 001 is a 24-bit ADC-DAC, the ability to simultaneously listen to 24 tracks, the presence of eight instead of two inputs on the board, etc. So if, for example, in the course of recording a presentation, you need to record a scene in which six people speak into six microphones, then the DIGI 001 will cope with this task. Add to that independent monitor output plus 24-bit file handling, while Nuendo and the cheap SoundBlaster only work with 16-bit files...

Pro Tools 5 LE allows you to do almost the same as Nuendo - to carry out non-linear editing, the same manipulations with audio files, plus a mini-sequencer that also allows you to record music using MIDI instruments.

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

S.T.: First of all, I could talk about the Pro Tools system. In order to prevent possible questions, I want to emphasize once again: it is necessary to distinguish Digidesign Pro Tools as trademark and Pro Tools as hardware. Under the brand name Pro Tools hides a whole range of products. The simplest system from this set is exactly the DIGI 001, which we talked about when describing semi-professional tasks. This is the simplest version of a whole product line that ends with systems based on dozens of workstations tied into a single network.

KP: Let's choose an option that can be used for dubbing simple professional films, TV shows, and so on.

S.T.: The next system we might consider is Pro Tools 24. To make it clear what problems it solves this system, we note that the last Xena series was voiced using this technique.

There are versions for both Mac OS and Windows NT. If we talk about the requirements for NT stations, then this should be a serious machine, for example, IBM Intelli Station M PRO, 512 RAM. The documentation states that the minimum requirements for a processor are Pentium II 233, but in reality you need at least a Pentium II 450 and, of course, a SCSI disk system, and you need a two-port accelerator to pull 64 tracks simultaneously.

Pro Tools 24 is a set of specialized boards signal processors based on Motorola. It is important to note that this system is based on coprocessors, that is, the machine's processor performs the work associated with input-output and displaying graphics on the screen, and all signal processing is performed on specialized DSP (Digital Signal Processing) coprocessors. This makes it possible to solve rather complex problems of information. It is this technology that is used to dub the so-called blockbusters. So, for example, for scoring the Titanic (only effects!) A system of 18 networked workstations was used.

The soundtrack in films like Titanic is a stunningly complex, time-varying soundscape. If you analyze a sound-rich five to ten minute excerpt from such a film and write down all the sounds that are used there, you get a list of hundreds of names. Of course, all these sounds are not heard from a VHS tape, and many do not even suspect how complex the sound picture is created in the film. (Moreover, most of these sounds are created synthetically and do not exist in nature.)

KP: You raised the issue of replacing natural sounds with more convincing ones. Where can I get these sound libraries and how much do they cost?

S.T.: The cost of such libraries - from fifty dollars and more, up to several thousand dollars. At the same time, all these sounds are mainly used for simple production at the level of cable networks. For professional films, even low-budget (not to mention expensive), all sounds are recorded independently.

KP: What is wrong with sounds from standard library for a professional film?

S.T.: In principle, I'm talking about how it's done in the West, or how it should be done, because in our country, out of poverty, people very often save on things that shouldn't be saved on. The fact is that a feature film reflects a certain individual intention of the director, and it is often almost impossible to find sound in libraries that fully corresponds to this intention.

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

S.T.: There is such a thing as the timbre of sound. You can emphasize or weaken certain components of this timbre, but you cannot radically change it. That is why all the noise for a professional film is recorded from scratch, and professionals do it. To give you an example: in the famous movie "Batman Returns" there was the sound of Batman's car. Can you please tell me in which library this sound can be found? Moreover, if we are talking about stereo sound and Surround technology, then each sound picture is simply unique. For example, if a helicopter flies towards the viewer and flies back, it is obvious that such a sound picture is tied to the plot. In this case, it is not necessary to record real sounds - most often they are created synthetically.

KP: Why is it impossible to record sounds from real physical processes and present them exactly as they occur in life? Why do you need to use some other, synthetic ones instead?

S.T.: We do not need to accurately recreate the sound of real physical, as you put it, processes. If a bomb explodes three meters from the foreground, then the viewer does not need to convey the sound that a soldier who is near the explosion site actually hears! We must convey some kind of conditional picture that will allow the viewer to imagine reality; at the same time, we focus on the peculiarities of its perception, on the artistic accents we need, and so on.