This standard specifies technical scheme of coding and decoding for multichannel digital audio compression, including bit stream format (syntactic structure and semanteme), decoding process and technical requirements of each decoding module; informative suggestion and implementation method are provided for the part adopting coding of this technology.
This standard is applicable to preserve or transmit high-quality multichannel digital audio on the channel with limited storage medium and limited bandwidth, such as digital audio broadcasting, digital TV (including different transmission modes such as satellite, earth and cable transmission), home audio, digital cinema, DVD, network streaming media and personal media player.
2 Normative References
The following standards contain provisions which, through reference in this standard, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding corrigenda), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document applies.
GB/T 17975.1-2000 Information Technology - Generic Coding of Moving Picures and Associated Audio Information - Part 1: Systems (idt ISO/IEC 13818-1: 1996)
GB/T 4880.2-2000 Codes for the Representation of Names of Languages - Part 2: Alpha-3 Code (eqv ISO 639-2: 1998)
ISO/IEC 8859-1: 1998 Information Technology - 8-bit Single-byte Coded Graphic Character Sets - Part 1: Latin Alphabet No. 1
3 Terms, Definitions and Abbreviations
For the purpose of this standard, the following terms, definitions and abbreviations apply.
3.1 Terms and Definitions
3.1.1
Audio data
Bit sequence (data) used to present the original audio signal after coding.
3.1.2
Audio sample
Sample value of PCM (Pulse Code Modulation) of encoder for input or decoder for output.
3.1.3
Auxiliary data
Data not belonging to the audio signal itself but related to the audio signal, including time code etc.
3.1.4
Bit stream
Bit sequence presenting original audio signal generated by the encoder in accordance with this standard.
3.1.5
Brief window function
Window function with total length being 256 samples, but only MDCT (Modified Discrete Cosine Transform) of 160 samples are used.
3.1.6
Critical band
Mathematical model of human ear resolving sound may be approximately presented by a subband filter bank and the bandwidth of filter bank forms approximate index rise along with the rising frequency. A subband of this filter bank is namely a critical band.
3.1.7
Downmix
Matrix calculation of N channels carried out to obtain channel quantity less than N (see Appendix D).
3.1.8
Frame
Audio data presenting one frame of audio signal generated by the encoder in accordance with this standard. It is the basic unit of bit stream in this standard. One frame in this standard may cover 128, 256, 512 or 1024 audio samples.
3.1.9
Frame header
