Annex 1
MPEG audio layer II (ISO/IEC 13818‑3): a generic coding standard
for two‑channel and multi‑channel sound for digital video
broadcasting, digital audio broadcasting and computer multimedia
1 Introduction
2 Principles of the
MPEG Layer II audio coding technique
2.1 Psychoacoustic
model
2.2 Filter bank
2.3 Determination and
coding of scale factors
2.4 Bit allocation
and encoding of bit allocation information
2.5 Quantization and
encoding of sub‑band samples
2.6 Layer II bit
stream structure
2.7 Layer II decoding
3 MPEG‑2
Audio: generic multi-channel audio coding
3.1 Characteristics
of the MPEG‑2 multi‑channel audio coding system
3.1.1 3/2-stereo presentation performance
3.1.2 Backward/forward compatibility with
ISO/IEC 11172‑3
3.1.3 Downward compatibility
3.1.4 Multilingual extension and associated
services
3.1.5 Low frequency effects channel
3.2 Composite coding
strategies for multi-channel audio
3.2.1 Dynamic crosstalk
3.2.2 Phantom coding of centre channel
3.2.3 Adaptive multi‑channel
prediction
3.2.4 Common masked threshold
3.2.5 Common bit pool
3.2.6 Transmission channel switching
4 Concluding
summary
Annex 2 Digital
Audio Compression (AC‑3) Standard (ATSC Standard)
Foreword
1 Introduction
1.1 Motivation
1.2 Encoding
1.3 Decoding
2 Scope
3 References
3.1 Normative
references
3.2 Informative
references
4 Notation,
definitions, and terminology
4.1 Compliance
notation
4.2 Definitions
4.3 Terminology
abbreviations
5 Bit stream syntax
5.1 Synchronization
frame
5.2 Semantics of
syntax specification
5.3 Syntax
specification
5.3.1 syncinfo – Synchronization information
5.3.2 bsi – Bit stream information
5.3.3 audblk – Audio block
5.3.4 auxdata – Auxiliary data
5.3.5 errorcheck – Error detection code
5.4 Description of
bit stream elements
5.4.1 syncinfo – Synchronization information
5.4.2 bsi – Bit stream information
5.4.3 audblk – Audio block
4
4
3
(cplinu == 1) && (cplbegf == 0)
2
5.4.4 auxdata – Auxiliary data field
5.4.5 errorcheck – Frame error detection
field
5.5 Bit stream
constraints
6 Decoding the AC‑3
bit stream
6.1 Introduction
6.2 Summary of
the decoding process
6.2.1 Input bit stream
6.2.2 Synchronization and error detection
6.2.3 Unpack BSI, side information
6.2.4 Decode exponents
6.2.5 Bit allocation
6.2.6 Process mantissas
6.2.7 Decoupling
6.2.8 Rematrixing
6.2.9 Dynamic range compression
6.2.10 Inverse transform
6.2.11 Window, overlap/add
6.2.12 Downmixing
6.2.13 PCM output buffer
6.2.14 Output PCM
7 Algorithmic
details
7.1 Exponent coding
7.1.1 Overview
7.1.2 Exponent strategy
7.1.3 Exponent decoding
7.2 Bit allocation
7.2.1 Overview
7.2.2 Parametric bit allocation
7.2.3 Bit allocation tables
7.3 Quantization and
decoding of mantissas
7.3.1 Overview
7.3.2 Expansion of mantissas for asymmetric
quantization (6 ≤ bap ≤ 15)
7.3.3 Expansion of mantissas for symmetrical
quantization (1 ≤ bap ≤ 5)
7.3.4 Dither for zero bit mantissas
(bap = 0)
7.3.5 Ungrouping of mantissas
7.4 Channel coupling
7.4.1 Overview
7.4.2 Sub‑band structure for coupling
7.4.3 Coupling coordinate format
7.5 Rematrixing
7.5.1 Overview
7.5.2 Frequency band definitions
7.5.3 Encoding technique
7.5.4 Decoding technique
7.6 Dialogue
normalization
7.6.1 Overview
7.7 Dynamic range
compression
7.7.1 Dynamic range control; dynrng, dynrng2
7.7.2 Heavy compression; compr, compr2
7.8 Downmixing
7.8.1 General downmix procedure
7.8.2 Downmixing into two channels
7.9 Transform
equations and block switching
7.9.1 Overview
7.9.2 Technique
7.9.3 Decoder implementation
7.9.4 Transformation equations
7.9.5 Channel gain range code
7.10 Error detection
7.10.1 CRC checking
7.10.2 Checking bit stream consistency
8 Encoding the AC‑3
bit stream
8.1 Introduction
8.2 Summary of the
encoding process
8.2.1 Input PCM
8.2.2 Transient detection
8.2.3 Forward transform
8.2.4 Coupling strategy
8.2.5 Form coupling channel
8.2.6 Rematrixing
8.2.7 Extract exponents
8.2.8 Exponent strategy
8.2.9 Dither strategy
8.2.10 Encode exponents
8.2.11 Normalize mantissas
8.2.12 Core bit allocation
8.2.13 Quantize mantissas
8.2.14 Pack AC‑3 frame
Appendix 1 to Annex 2
(Normative) AC‑3 elementary streams in the MPEG‑2
multiplex
1 Scope
2 Introduction
3 Detailed specification
for System A (ATSC)
3.1 Stream_type
3.2 Stream_id
3.3 Registration_descriptor
3.4 AC‑3 audio_stream_descriptor
3.5 ISO_639_language_code
3.6 STD audio buffer
size
4 Detailed
specification for System B (DVB)
4.1 Stream_type
4.2 Stream_id
4.3 Service
information
4.3.1 AC‑3_descriptor
4.3.2 AC‑3_descriptor syntax
4.3.3 AC‑3 component_type values
4.4 STD audio buffer
size
5 PES constraints
5.1 Encoding
5.2 Decoding
6 Byte‑alignment