Files with digitized audio
Sound files in which the original continuous (“analog”) waveform is recorded as a sequence of short discrete values of the amplitudes of the sound signal, measured (“selected”) at equal time intervals and with an interval very small between them.
The process of replacing a continuous signal with a sequence of its values is called sampling, and this form of recording is pulse code. The hardware implementation of digital audio processing is that an analog-to-digital converter (ADC) converts an analog signal into a set of digital measurements and, during playback, a digital-to-analog converter (DAC) performs the reverse process: convert a digital signal into analog. There are two types of files with digitized audio: header and no header.
Files with music notation (song file, music file): sound files that contain a sequence of commands indicating which note and by which instrument and for how long to play at any given time. The format can foresee the simultaneous execution of several musical instruments, in this case it speaks of the corresponding number of voices.
Edit Basic standards for multichannel audio
Dolby Stereo is a standard for digital movie sound recording / playback technology for cinemas that allows four channels to be encoded into two movie soundtracks: left, center, right, and rear. The signal read from the film is converted by the decoder into four channels, which gives a surround sound effect. Without a decoder, the sound is played as normal two-channel stereo. The standard was proposed by Dolby Laboratories in 1976.
DDS (Dolby Surround Sound) is a standard for digital recording / playback of movie soundtracks in the frequency range 100-7000 Hz for home theater systems. The standard allows encoding three channels in two soundtracks of a movie: left, right and rear. The signal read from the film is decoded into three channels. Without a decoder, the sound is played as normal two-channel stereo. The standard was proposed by Dolby Laboratories in 1982.
DPL (Dolby Surround Pro Logic) is an evolution of the DDS standard for home theater systems with three to four sound channels: left, center, right and surround. The standard was proposed by Dolby Laboratories in 1987.
Dolby Digital is a standard for encoding / decoding six-channel (5 + 1) audio recording in the 20 Hz to 20 kHz range: 5 surround channels and one low-frequency channel (subwoofer). The standard was proposed by Dolby Laboratories in 1992. The frequency range of the five channels is 3 Hz to 20 kHz, the subwoofer is 3 Hz to 120 kHz.
Dolby Digital AC3 is an addition to the Dolby Digital standard with a scheme that provides an audio recording compression density of 12: 1 or more at a 64 to 640 Kbps bit rate with high quality playback.
Dolby Surround AC3 is a simplified version of the Dolby Digital home theater standard with reduced bit rates.
DTS (Digital Theater System) is a standard for six-channel (5 + 1) sound recording on music DVDs, close to Dolby Digital, with a lower compression ratio (4: 1) and a faster data rate. high (bit rate – 882 Kbps). Due to this, in addition to the use of a perfect compression algorithm, it is characterized by high-quality sound recording and reproduction. The recording uses a 48 kHz sample rate, making it the highest quality DVD audio standard ever recorded.
Dolby Pro Logic II is an evolution of the Dolby Surround Pro Logic standard, which breaks down normal stereo sound into six channels: 5 + 1.
Dolby Pro Logic Iix is an evolution of the Dolby Surround Pro Logic standard, which provides stereo sound decomposition into 7 (6 + 1) or 8 channels (7 + 1). Possible decoding modes: Movie: mirroring the center channel or rear channels; game (Play): the signal is also sent to the “new channels”; Music).
Dolby Digital EX is a home theater variant of the Dolby Pro Logic Iix standard.
Dolby Digital Surround EX is an expanded version of up to 7 channels (6 + 1) of the Dolby Digital Surround standard, in which there is an additional rear channel (rear) that doubles the center channel if the sound is recorded in 5 + 1 format. If the sound is recorded in 6 + 1 format, the additional channel becomes a full surround channel.
DTS-ES is an analog of the Dolby Digital EX standard developed by DTS; allows you to encode audio in 6 + 1 and 7 + 1 formats and decompose audio encoded in DTS (5 + 1) format into 7 (6 + 1) or 8 (7 + 1) channels.
