ISO/IEC 14496-3:2001/Cor 1:2002

Information technology - Coding of audio-visual objects - Part 3: Audio - Technical Corrigendum 1

Technologies de l'information — Codage des objets audiovisuels — Partie 3: Codage audio — Rectificatif technique 1

General Information

• Status: Withdrawn
• Publication Date: 24-Nov-2002
• Withdrawal Date: 24-Nov-2002
• ICS: 35.040 - Information coding
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 14-Mar-2006
• Completion Date: 30-Oct-2025

Relations

• Revised: ISO/IEC 14496-3:2005 - Information technology - Coding of audio-visual objects - Part 3: Audio
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL STANDARD ISO/IEC 14496-3:2001
TECHNICAL CORRIGENDUM 1
Published 2002-12-01
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
INTERNATIONAL ELECTROTECHNICAL COMMISSION • МЕЖДУНАРОДНАЯ ЭЛЕКТРОТЕХНИЧЕСКАЯ КОМИССИЯ • COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE

Information technology — Coding of audio-visual objects —
Part 3:
Audio
TECHNICAL CORRIGENDUM 1
Technologies de l'information — Codage des objets audiovisuels —
Partie 3: Codage audio
RECTIFICATIF TECHNIQUE 1
Technical Corrigendum 1 to ISO/IEC 14496-3:2001 was prepared by Joint Technical Committee ISO/IEC
JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia
information.
ICS 35.040 Ref. No. ISO/IEC 14496-3:2001/Cor.1:2002(E)
©  ISO/IEC 2002 – All rights reserved
Published in Switzerland
ISO/IEC 14496-3:2001/Cor.1:2002(E)
Information technology — Coding of audio-visual objects —
Part 3:
Audio
TECHNICAL CORRIGENDUM 1
Throughout the text, replace the term
„
bit stream
”
with
„
bitstream
”.
Throughout the text replace
„
scaleable
”
with
„
scalable
”.
Throughout the text replace
„
indexes
”
with
„
indices
”.
In clause (Introduction), replace
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ISO/IEC 14496-3:2001/Cor.1:2002(E)
„
MPEG-4 has no standard for transport. In all of the MPEG-4 tools for audio and visual coding, the coding
standard ends at the point of constructing a sequence of access units that contain the compressed data. The
MPEG-4 Systems (ISO/IEC 14496-1:2001) specification describes how to convert the individually coded objects
into a bitstream that contains a number of multiplexed sub-streams.
There is no standard mechanism for transport of this stream over a channel; this is because the broad range of
applications that can make use of MPEG-4 technology have delivery requirements that are too wide to easily
characterize with a single solution. Rather, what is standardized is an interface (the Delivery Multimedia Interface
Format, or DMIF, specified in ISO/IEC 14496-6:1999) that describes the capabilities of a transport layer and the
communication between transport, multiplex, and demultiplex functions in encoders and decoders. The use of
DMIF and the MPEG-4 Systems bitstream specification allows transmission functions that are much more
sophisticated than are possible with previous MPEG standards.
”
with
„
MPEG-4 has no standard for transport. In all of the MPEG-4 tools for audio coding, the coding standard ends at
the point of constructing access units that contain the compressed data. The MPEG-4 Systems (ISO/IEC 14496-1)
specification describes how to convert these individually coded access units into elementary streams.
There is no standard transport mechanism of these elementary streams over a channel. This is because the broad
range of applications that can make use of MPEG-4 technology have delivery requirements that are too wide to
easily characterize with a single solution. Rather, what is standardized is an interface (the Delivery Multimedia
Interface Format, or DMIF, specified in ISO/IEC 14496-6) that describes the capabilities of a transport layer and the
communication between transport, multiplex, and demultiplex functions in encoders and decoders. The use of
DMIF and the MPEG-4 Systems specification allows transmission functions that are much more sophisticated than
are possible with previous MPEG standards.
”.
In clause (Introduction), replace multiplex, storage and transmission formats table with:
„
Format Functionality defined in Functionality originally Description
MPEG-4: defined in:
FlexMux ISO/IEC 14496-1 - Flexible Multiplex scheme
(normative)
LATM ISO/IEC 14496-3 - Low Overhead Audio Transport
(normative) Multiplex
ADIF ISO/IEC 14496-3 ISO/IEC 13818-7 Audio Data Interchange Format,
(informative) (normative) (AAC only)
MP4FF ISO/IEC 14496-1 - MPEG-4 File Format
(normative)
ADTS ISO/IEC 14496-3 ISO/IEC 13818-7 Audio Data Transport Stream,
(informative) (normative, exemplarily) (AAC only)
LOAS ISO/IEC 14496-3 - Low Overhead Audio Stream, based
(normative, exemplarily) on LATM, three versions are
available:
AudioSyncStream()
EPAudioSyncStream()
AudioPointerStream()
”.
Remove subclause 2.2 (Definitions).
Remove subclause 3.2 (Definitions).
2 © ISO/IEC 2002 — All rights reserved
Transmission Storage Multiplex

ISO/IEC 14496-3:2001/Cor.1:2002(E)
Remove subclause 4.3 (GA-specific definitions).
Remove subclause 5.3 (Definitions).
Remove subclause 6.2 (Definitions).
Remove subclause 7.2 (Definitions).
Replace subclause 1.3 (Terms and Definitions) with the following:
“
1. AAC: Advanced Audio Coding.
2. Audio access unit: An individually accessible portion of audio data within an elementary stream.
3. Audio composition unit: An individually accessible portion of the output that an audio decoder produces
from audio access units.
4. Absolute time: The time at which sound corresponding to a particular event is really created; time in the
real-world. Contrast score time.
5. Actual parameter: The expression which, upon evaluation, is passed to an opcode as a parameter value.
6. A-cycle: See audio cycle.
7. Adaptive codebook: An approach to encode the long-term periodicity of the signal. The entries of the
codebook consists of overlapping segments of past excitations.
8. Alias: Mirrored spectral component resulting from sampling.
9. Analysis filterbank: Filterbank in the encoder that transforms a broadband PCM audio signal into a set of
spectral coefficients.
10. Ancillary data: Part of the bitstream that might be used for transmission of ancillary data.
11. API: Application Programming Interface.
12. A-rate: See audio rate.
13. Asig: The lexical tag indicating an a-rate variable.
14. Audio buffer: A buffer in the system target decoder (see ISO/IEC 13818-1) for storage of compressed audio
data.
15. Audio cycle: The sequence of processing which computes new values for all a-rate expressions in a
particular code block.
16. Audio rate: The rate type associated with a variable, expression or statement which may generate new
values as often as the sampling rate.
17. Audio sample: A short snippet or clip of digitally represented sound. Typically used in wavetable synthesis.
18. AudioBIFS: The set of tools specified in ISO/IEC 14496-1 (MPEG-4 Systems) for the composition of audio
data in interactive scenes.
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19. Authoring: In Structured Audio, the combined processes of creatively composing music and sound control
scripts, creating instruments which generate and alter sound, and encoding the instruments, control scripts,
and audio samples in MPEG-4 Structured Audio format.
20. Backus-Naur Format: (BNF) A format for describing the syntax of programming languages, used here to
specify the SAOL and SASL syntax.
21. Backward compatibility: A newer coding standard is backward compatible with an older coding standard if
decoders designed to operate with the older coding standard are able to continue to operate by decoding all
or part of a bitstream produced according to the newer coding standard.
22. Bandwidth scalability: The possibility to change the bandwidth of the signal during transmission.
23. Bank: A set of samples used together to define a particular sound or class of sounds with wavetable
synthesis.
24. Bark: The Bark is the standard unit corresponding to one critical band width of human hearing.
25. Beat: The unit in which score time is measured.
26. Bitrate: The rate at which the compressed bitstream is delivered to the input of a decoder.
27. Bitrate scalability: The possibility to transmit a subset of the bitstream and still decode the bitstream with
the same decoder.
28. Bitstream verifier: A process by which it is possible to test and verify that all the requirements specified in
ISO/IEC 14496-3 are met by the bitstream.
29. Bitstream; stream: An ordered series of bits that forms the coded representation of the data.
30. Block companding: Normalizing of the digital representation of an audio signal within a certain time period.
31. BNF: See Backus-Naur Format.
32. BSAC: Bit Sliced Arithmetic Coding
33. Bus: An area in memory which is used to pass the output of one instrument into the input of another.
34. Byte: Sequence of 8-bits.
35. Byte aligned: A bit in a data function is byte-aligned if its position is a multiple of 8-bits from the first bit of
this data function.
36. CELP: Code Excited Linear Prediction.
37. Center channel: An audio presentation channel used to stabilize the central component of the frontal stereo
image.
38. Channel: A sequence of data representing an audio signal intended to be reproduced at one listening
position.
39. Coded audio bitstream: A coded representation of an audio signal.
40. Coded representation: A data element as represented in its encoded form.
41. Composition (compositing): Using a scene description to mix and combine several separate audio tracks
into a single presentation.
42. Compression: Reduction in the number of bits used to represent an item of data.
43. Constant bitrate: Operation where the bitrate is constant from start to finish of the coded bitstream.
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44. Context: See state space.
45. Control: An instruction used to describe how to use a particular synthesis method to produce sound.
EXAMPLES:
“Using the piano instrument, play middle C at medium volume for 2 seconds.”
“Glissando the violin instrument up to middle C.”
“Turn off the reverberation for 8 seconds.”
46. Control cycle: The sequence of processing which computes new values for all control-rate expressions in a
particular code block.
47. Control period: The length of time (typically measured in audio samples) corresponding to the control rate.
48. Control rate: (1) The rate at which instantiation and termination of instruments, parametric control of running
instrument instances, sharing of global variables, and other non-sample-by-sample computation occurs in a
particular orchestra. (2) The rate type of variables, expressions, and statements that can generate new
values as often as the control rate.
49. Core coder: The term core coder is used to denote a base layer coder in certain scalability configurations. A
core coder does not code the spectral samples of the MDCT filterbank of the subsequent AAC coding layers,
but operates on a time domain signal. The output of the core decoder has to be up-sampled and transformed
into the spectral domain, before it can be combined with the output of the AAC coding layers. Within the
MPEG-4 Audio standard only the MPEG-4 CELP coder is a valid core coder. However, in principal, also
another AAC coding layer, operating at a lower sampling rate, could be used on the time domain signal, and
then combined with the other coding layer in exactly the same way as described for the CELP coder, and
would therefore be called a core coder.
50. CRC: The Cyclic Redundancy Check to verify the correctness of data.
51. Critical band: This unit of bandwidth represents the standard unit of bandwidth expressed in human auditory
terms, corresponding to a fixed length on the human cochlea. It is approximately equal to 100 Hz at low
frequencies and 1/3 octave at higher frequencies, above approximately 700 Hz.
52. Data element: An item of data as represented after encoding and before decoding.
53. Data function: An encapsulation of data elements forming a logic unit.
54. Decoded stream: The decoded reconstruction of a compressed bitstream.
55. Decoder: An embodiment of a decoding process.
56. Decoding (process): The process that reads an input coded bitstream and outputs decoded audio samples.
57. Demultiplexing: Splitting one bitstream into several.
58. DFT: Discrete Fourier Transform.
59. Digital storage media; DSM: A digital storage or transmission device or system.
60. Dimension conversion: A method to convert a dimension of a vector by a combination of low pass filtering
and linear interpolation.
61. Discrete cosine transform; DCT: Either the forward discrete cosine transform or the inverse discrete
cosine transform. The DCT is an invertible, discrete orthogonal transformation.
62. Downmix: A matrixing of n channels to obtain less than n channels.
63. Duration: The amount of time between instantiation and termination of an instrument instance.
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64. Editing: The process by which one or more coded bitstreams are manipulated to produce a new coded
bitstream. Conforming edited bitstreams must meet the requirements defined in part 3 of ISO/IEC 14496.
65. Elementary stream (ES): A sequence of data that originates from a single producer in the transmitting
MPEG-4 Terminal and terminates at a single recipient, e.g. an AVObject or a Control Entity in the receiving
MPEG-4 Terminal. It flows through one FlexMux Channel.
66. Encoder: An embodiment of an encoding process.
67. Encoding (process): A process, not specified in ISO/IEC 14496, that reads a stream of input audio samples
and produces a valid coded bitstream as defined in part 3 of ISO/IEC 14496.
68. Enhancement layer(s): The part(s) of the bitstream that is possible to drop in a transmission and still
decode the bitstream.
69. Entropy coding: Variable length lossless coding of the digital representation of a signal to reduce statistical
redundancy.
70. Envelope: A loudness-shaping function applied to a sound, or more generally, any function controlling a
parametric aspect of a sound
71. EP: Error Protection
72. ER: Error resilience or Error Resilient (as appropriate)
73. Event: One control instruction.
74. Excitation: The excitation signal represents the input to the LPC module. The signal consists of
contributions that cannot be covered by the LPC model.
75. Expression: A mathematical or functional combination of variable values, symbolic constants, and opcode
calls.
76. FFT: Fast Fourier Transformation. A fast algorithm for performing a discrete Fourier transform (an orthogonal
transform).
77. Filterbank: A set of band-pass filters covering the entire audio frequency range.
78. Fine rate control: The possibility to change the bitrate by, under some circumstances, skipping transmission
of the LPC indices.
79. Fixed codebook: The fixed codebook contains excitation vectors for the speech synthesis filter. The
contents of the codebook are non-adaptive (i.e. fixed).
80. Flag: A variable which can take one of only the two values defined in this specification.
81. Formal parameter: The syntactic element that gives a name to one of the parameters of an opcode.
82. Forward compatibility: A newer coding standard is forward compatible with an older coding standard if
decoders designed to operate with the newer coding standard are able to decode bitstreams of the older
coding standard.
83. Frame: A part of the audio signal that corresponds to a certain number of audio PCM samples.
84. Fs: Sampling frequency.
85. FSS: Frequency Selective Switch. Module which selects one of two input signals independently in each
scalefactor band.
86. Fundamental frequency: A parameter which represents signal periodicity in frequency domain.
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87. Future wavetable: A wavetable that is declared but not defined in the SAOL orchestra; its definition must
arrive in the bitstream before it is used.
88. Global block: The section of the orchestra that describes global variables, route and send statements,
sequence rules, and global parameters.
89. Global context: The state space used to hold values of global variables and wavetables.
90. Global parameters: The sampling rate, control rate, and number of input and output channels of audio
associated with a particular orchestra.
91. Global variable: A variable that can be accessed and/or changed by several different instruments.
92. Grammar: A set of rules that describes the set of allowable sequences of lexical elements comprising a
particular language.
93. Guard expression: The expression standing at the front of an if, while, or else statement that determines
whether or how many times a particular block of code is executed.
94. Hann window: A time function applied sample-by-sample to a block of audio samples before Fourier
transformation.
95. Harmonic lines: A set of spectral components having a common fundamental frequency.
96. Harmonic magnitude: Magnitude of each harmonic.
97. Harmonic synthesis: A method to obtain a periodic excitation from harmonic magnitudes.
98. Harmonics: Samples of frequency spectrum at multiples of the fundamental frequency.
99. HCR: Huffman codebook reordering
100. HILN: Harmonic and Individual Lines plus Noise (parametric audio coding).
101. Huffman coding: A specific method for entropy coding.
102. HVXC: Harmonic Vector eXcitation Coding (parametric speech coding).
103. Hybrid filterbank: A serial combination of subband filterbank and MDCT. Used in MPEG-1 and MPEG-2
Audio.
104. I-cycle: See initialisation cycle.
105. IDCT: Inverse Discrete Cosine Transform.
106. Identifier: A sequence of characters in a textual SAOL program that denotes a symbol.
107. IFFT: Inverse Fast Fourier Transform.
108. IMDCT: Inverse Modified Discrete Cosine Transform.
109. Index: Number indicating the quantized value(s).
110. Individual line: A spectral component described by frequency, amplitude and phase.
111. Informative: Aspects of a standards document that are provided to assist implementers, but are not required
to be implemented in order for a particular system to be compliant to the standard.
112. Initial phase: A phase value at the onset of voiced signal in harmonic synthesis.
113. Initialisation cycle: See initialisation pass.
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ISO/IEC 14496-3:2001/Cor.1:2002(E)
114. Initialisation pass: The sequence of processing that computes new values for each i-rate expression in a
particular code block.
115. Initialisation rate: The rate type of variables, expressions, and statements that are set once at instrument
instantiation and then do not change.
116. Instance: See instrument instantiation.
117. Instantiation: The process of creating a new instrument instantiation based on an event in the score or
statement in the orchestra.
118. Instrument: An algorithm for parametric sound synthesis, described using SAOL. An instrument
encapsulates all of the algorithms needed for one sound-generation element to be controlled with a score.
NOTE - An MPEG-4 Structured Audio instrument does not necessarily correspond to a real-world instrument.
A single instrument might be used to represent an entire violin section, or an ambient sound such as the
wind. On the other hand, a single real-world instrument that produces many different timbres over its
performance range might be represented using several SAOL instruments.
119. Instrument instantiation: The state space created as the result of executing a note-creation event with
respect to a SAOL orchestra.
120. Intensity stereo: A method of exploiting stereo irrelevance or redundancy in stereophonic audio
programmes based on retaining at high frequencies only the energy envelope of the right and left channels.
121. Interframe prediction: A method to predict a value in the current frame from values in the previous frames.
Interframe prediction is used in VQ of LSP.
122. International Phonetic Alphabet; IPA : The worldwide agreed symbol set to represent various phonemes
appearing in human speech.
123. I-pass: See initialisation pass.
124. IPQF: inverse polyphase quadrature filter
125. I-rate: See initialisation rate.
126. Ivar: The lexical tag indicating an i-rate variable.
127. Joint stereo coding: Any method that exploits stereophonic irrelevance or stereophonic redundancy.
128. Joint stereo mode: A mode of the audio coding algorithm using joint stereo coding.
129. K-cycle: See control cycle.
130. K-rate: See control rate.
131. Ksig: The lexical tag indicating a k-rate variable.
132. Lexical element: See token.
133. Lip shape pattern : A number that specifies a particular pattern of the preclassified lip shape.
134. Lip synchronization : A functionality that synchronizes speech with corresponding lip shapes.
135. Looping: A typical method of wavetable synthesis. Loop points in an audio sample are located and the
sound between those endpoints is played repeatedly while being simultaneously modified by envelopes,
modulators, etc.
136. Low frequency enhancement (LFE) channel: A limited bandwidth channel for low frequency audio effects
in a multichannel system.
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137. LPC: Linear Predictive Coding.
138. LPC residual signal: A signal filtered by the LPC inverse filter, which has a flattened frequency spectrum.
139. LPC synthesis filter: An IIR filter whose coefficients are LPC coefficients. This filter models the time varying
vocal tract.
140. LSP: Line Spectral Pairs.
141. LTP: Long Term Prediction.
142. M/S stereo: A method of removing imaging artifacts as well as exploiting stereo irrelevance or redundancy in
stereophonic audio programs based on coding the sum and difference signal instead of the left and right
channels.
143. Main audio channels: All single_channel_elements or channel_pair_elements in one program.
144. Mapping: Conversion of an audio signal from time to frequency domain by subband filtering and/or by
MDCT.
145. Masking: A property of the human auditory system by which an audio signal cannot be perceived in the
presence of another audio signal.
146. Masking threshold: A function in frequency and time below which an audio signal cannot be perceived by
the human auditory system.
147. MIDI: The Musical Instrument Digital Interface standards. Certain aspects of the MPEG-4 Structured Audio
tools provide interoperability with MIDI standards.
148. Mixed voiced frame: A speech segment which has both voiced and unvoiced components.
149. Modified discrete cosine transform (MDCT): A transform which has the property of time domain aliasing
cancellation.
150. Moving picture dubbing : A functionality that assigns synthetic speech to the corresponding moving picture
while utilizing lip shape pattern information for synchronization.
151. MPE: Multi Pulse Excitation.
152. MPEG-4 Audio Text-to-Speech Decoder : A device that produces synthesized speech by utilizing the M-
TTS bitstream while supporting all the M-TTS functionalities such as speech synthesis for FA and MP
dubbing.
153. M-TTS sentence : This defines the information such as prosody, gender, and age for only the corresponding
sentence to be synthesized.
154. M-TTS sequence : This defines the control information which affects all M-TTS sentences that follow this M-
TTS sequence.
155. Multichannel: A combination of audio channels used to create a spatial sound field.
156. Multilingual: A presentation of dialogue in more than one language.
157. Multiplexing: Combining several bitstreams into one.
158. Natural Sound: A sound created through recording from a real acoustic space. Contrasted with synthetic
sound.
159. NCC: Number of Considered Channels. In case of AAC, it is the number of channels represented by the
elements SCE, independently switched CCE and CPE, i.e. once the number of SCEs plus once the number
of independently switched CCEs plus twice the number of CPEs. With respect to the naming conventions of
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ISO/IEC 14496-3:2001/Cor.1:2002(E)
the MPEG-AAC decoders and payloads, NCC=A+I. This number is used to derive the required decoder input
buffer size (see subclause 4.5.3.1). In case of other codecs, it tis the total number of channels.
160. Noise component: A signal component modeled as noise.
161. Non-tonal component: A noise-like component of an audio signal.
162. Normative: Those aspects of a standard that must be implemented in order for a particular system to be
compliant to the standard.
163. Nyquist sampling: Sampling at or above twice the maximum bandwidth of a signal.
164. OD: Object Descriptor.
165. Opcode: A parametric signal-processing function that encapsulates a certain functionality so that it may be
used by several instruments.
166. Orchestra: The set of sound-generation and sound-processing algorithms included in an MPEG-4 bitstream.
Includes instruments, opcodes, routing, and global parameters.
167. Orchestra cycle: A complete pass through the orchestra, during which new instrument instantiations are
created, expired ones are terminated, each instance receives one k-cycle and one control period worth of a-
cycles, and output is produced.
168. Padding: A method to adjust the average length of an audio frame in time to the duration of the
corresponding PCM samples, by conditionally adding a slot to the audio frame.
169. Parameter: A variable within the syntax of this specification which may take one of a range of values. A
variable which can take one of only two values is a flag or indicator and not a parameter.
170. Parameter fields: The names given to the parameters to an instrument.
171. Parser: Functional stage of a decoder which extracts from a coded bitstream a series of bits representing
coded elements.
172. P-fields: See parameter fields.
173. Phoneme/bookmark-to-FAP converter : A device that converts phoneme and bookmark information to
FAPs.
174. Pi: The constant � = 3.14159.
175. Pitch: A parameter which represents signal periodicity in the time domain. It is expressed in terms of the
number of samples.
176. Pitch control: A functionality to control the pitch of the synthesized speech signal without changing its
speed.
177. PNS: Perceptual Noise Substitution.
178. Polyphase filterbank: A set of equal bandwidth filters with special phase interrelationships, allowing an
efficient implementation of the filterbank.
179. Postfilter: A filter to enhance the perceptual quality of the synthesized speech signal.
180. PQF: polyphase quadrature filter
181. Prediction: The use of a predictor to provide an estimate of the sample value or data element currently
being decoded.
182. Prediction error: The difference between the actual value of a sample or data element and its predictor.
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183. Predictor: A linear combination of previously decoded sample values or data elements.
184. Presentation channel: An audio channel at the output of the decoder.
185. Production rule: In Backus-Naur Form grammars, a rule that describes how one syntactic element may be
expressed in terms of other lexical and syntactic elements.
186. Program: A set of main audio channels, coupling_channel_elements (see subclause 4.5.2.1),
lfe_channel_elements (see subclause 4.5.2.1) and associated data streams intended to be decoded and
played back simultaneously. A program may be defined by default, or specifically by a
program_config_element (see subclause 4.5.1.2). A given single_channel_element (see subclause 4.5.2.1),
channel_pair_element (see subclause 4.5.2.1), coupling_channel_element, lfe_channel_element or data
channel may accompany one or more programs in any given bitstream.
187. PSNR: Peak Signal to Noise Ratio.
188. Psychoacoustic model: A mathematical model of the masking behaviour of the human auditory system.
189. Random access: The process of beginning to read and decode the coded bitstream at an arbitrary point.
190. Rate semantics: The set of rules describing how rate types are assigned to variables, expressions,
statements, and opcodes, and the normative restrictions that apply to a bitstream regarding combining these
elements based on their rate types.
191. Rate type: The “speed of execution” associated with a particular variable, expression, statement, or opcode.
192. Rate-mismatch error: The condition that results when the rate semantics rules are violated in a particular
SAOL construction. A type of syntax error.
193. Reserved: The term "reserved" when used in the clauses defining the coded bitstream indicates that the
value may be used in the future for ISO/IEC defined extensions.
194. Route statement: A statement in the global block that describes how to place the output of a certain set of
instruments onto a bus.
195. RPE: Regular Pulse Excitation.
196. Run-time error: The condition that results from improper calculations or memory accesses during execution
of a SAOL orchestra.
197. RVLC: Reversible Variable Length Coding
198. Sample: See Audio sample.
199. Sample Bank Format: A component format of MPEG-4 Structured Audio that allows the description of a set
of samples for use in wavetable synthesis and processing methods to apply to them.
200. Sampling Frequency (Fs): Defines the rate in Hertz which is used to digitize an audio signal during the
sampling process.
201. SAOL: The Structured Audio Orchestra Language, pronounced like the English word “sail”. SAOL is a
digital-signal processing language that allows for the description of arbitrary synthesis and control algorithms
as part of the content bitstream.
202. SAOL orchestra: See orchestra.
203. SASBF: The MPEG-4 Structured Audio Sample Bank Format, an efficient format for the transmission of
blocks of wavetable (sample data) compatible with the MIDI method for the same.
204. SASL: The Structured Audio Score Language. SASL is a simple format that allows for powerful and flexible
control of music and sound synthesis.
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205. SBA: Segmented Binary Arithmetic Coding which is the error resilient tool for BSAC
206. Scalefactor: Factor by which a set of values is scaled before quantization.
207. Scalefactor band: A set of spectral coefficients which are scaled by one scalefactor.
208. Scalefactor index: A numerical code for a scalefactor.
209. Scheduler: The component of MPEG-4 Structured Audio that describes the mapping from control
instructions to sound synthesis using the specified synthesis techniques. The scheduler description provides
normative bounds on event-dispatch times and responses.
210. Scope : The code within which access to a particular variable name is allowed.
211. Score: A description in some format of the sequence of control parameters needed to generate a desired
music composition or sound scene. In MPEG-4 Structured Audio, scores are described in SASL and/or MIDI.
212. Score time: The time at which an event happens in the score, measured in beats. Score time is mapped to
absolute time by the current tempo.
213. Semantics: The rules describing what a particular instruction or bitstream element should do. Most aspects
of bitstream and SAOL semantics are normative in MPEG-4.
214. Send statement: A statement in the global block that describes how to pass a bus on to an effect instrument
for post-processing.
215. Sequence rules: The set of rules, both default and explicit, given in the global block that define in what order
to execute instrument instantiations during an orchestra cycle.
216. SIAQ: Scalable Inverse AAC Quantization Module.
217. Side information: Information in the bitstream necessary for controlling the decoder.
218. Signal variable: A unit of memory, labelled with a name, that holds intermediate processing results. Each
signal variable in MPEG-4 Structured Audio is instantaneously representable by a 32-bit floating point value.
219. Sinusoidal synthesis: A method to obtain a time domain waveform by a sum of amplitude modulated
sinusoidal waveforms.
220. Spatialisation: The process of creating special sounds that a listener perceives as emanating from a
particular direction.
221. Spectral coefficients: Discrete frequency domain data output from the analysis filterbank.
222. Spectral envelope: A set of harmonic magnitudes.
223. Speed control: A functionality to control the speed of the synthesized speech signal without changing its
pitch or phonemes.
224. Spreading function: A function that describes the frequency spread of masking effects.
225. SQ: Scalar Quantization.
226. State space: A set of variable-value associations that define the current computational state of an
instrument instantiation or opcode call. All the “current values” of the variables in an instrument or opcode
call.
227. Statement: “One line” of a SAOL orchestra.
228. Stereo-irrelevant: A portion of a stereophonic audio signal which does not contribute to spatial perception.
12 © ISO/IEC 2002 — All rights reserved

ISO/IEC 14496-3:2001/Cor.1:2002(E)
229. Structured audio: Sound-description methods that make use of high-level models of sound generation and
control. Typically involving synthesis description, structured audio techniques allow for ultra-low bitrate
description of complex, high-quality sounds.
230. Stuffing (bits); stuffing (bytes): Code-words that may be inserted at particular locations in the coded
bitstream that are discarded in the decoding process. Their purpose is to increase the bitrate of the stream
which would otherwise be lower than the desired bitrate.
231. Surround channel: An audio presentation channel added to the front channels (L and R or L, R, and C) to
enhance the spatial perception.
232. Symbol: A sequence of characters in a SAOL program, or a symbol token in a MPEG-4 Structured Audio
bitstream, that represents a variable name, instrument name, opcode name, table name, bus name, etc.
233. Symbol table: In an MPEG-4 Structured Audio bitstream, a sequence of data that allows the tokenised
representation of SAOL and SASL code to be converted back to a readable textual representation. The
symbol table is an optional component.
234. Symbolic constant: A floating-point value explicitly represented as a sequence of characters in a textual
SAOL orchestra, or as a token in a bitstream.
235. Syncword: A code embedded in audio transport bitstreams that identifies the start of a transport frame.
236. Syntax: The rules describing what a particular instruction or bitstream element should look like. All aspects
of bitstream and SAOL syntax are normative in MPEG-4.
237. Syntax error: The condition that results when a bitstream element does not comply with its governing rules
of syntax.
238. Synthesis: The process of creating sound based on algorithmic descriptions.
239. Synthesis filterbank: Filterbank in the decoder that reconstructs a PCM audio signal from subband
samples.
240. Synthetic Sound: Sound created through synthesis.
241. Tempo: The scaling parameter that specifies the relationship between score time and absolute time. A
tempo of 60 beats per minute means that the score time measured in beats is equivalent to the absolute time
measured in seconds; higher numbers correspond to faster tempi, so that 120 beats per minute is twice as
fast.
242. Terminal: The “client side” of an MPEG transaction; whatever hardware and software are necessary in a
particular implementation to allow the capabilities described in this document.
243. Termination: The process of destroying an instrument instantiation when it is no longer needed.
244. Text-to-speech synthesizer : A device producing synthesized speech according to the input sentence
character strings.
245. Timbre: The combined features of a sound that allow a listener to recognise such aspects as the type of
instrument, manner of performance, manner of sound generation, etc. Those aspects of sound that
distinguish sounds equivalent in pitch and loudness.
246. TNS: Temporal Noise Shaping
247. Token: A lexical element of a SAOL orchestra a keyword, punctuation mark, symbol name, or symbolic
constant.
248. Tokenisation: The process of converting a orchestra in textual SAOL format into a bitstream representation
consisting of a stream of tokens.
© ISO/IEC 2002— All rights reserved 13

ISO/IEC 14496-3:2001/Cor.1:2002(E)
249. Tonal component: A sinusoid-like component of an audio signal.
250. Trick mode : A set of functions that enables stop, play, forward, and backward operations for users.
251. TTSI: Text to Speech Interface.
252. TwinVQ: Transform domain Weighted Interleave Vector Quantization.
253. Unvoiced frame: Frame containing unvoiced speech which looks like random noise with no periodicity.
254. V/UV decision: Decision whether the current frame is voiced or unvoiced or mixed voiced.
255. Variable: See signal variable.
256. Variable bitrate: Operation where the bitrate varies with time during the decoding of a coded bitstream.
257. Variable length code (VLC): A code word assigned by variable length encoder (See variable length coding).
258. Variable length coding: A reversible procedure for coding that assigns shorter code-words to frequent
symbols and longer code-words to less frequent symbols.
259. Variable length decoder: A procedure to obtain the symbols encoded with a variable length coding
technique.
260. Variable length encoder: A procedure to assign variable length codewords to symbols.
261. VCB11: Virtual Codebooks for codebook 11.
262. Vector quantizer: Tool that quantizes several values to one index.
263. Virtual codebook: If several codebook values refer to one and the same physical codebook, these values
are called virtual codebooks.
264. Voiced frame: A voiced speech segment is known by its relatively high energy content, but more importantly
it contains periodicity which is called the pitch of the voiced speech.
265. VQ: Vector Quantization.
266. VXC: Vector eXcitation Coding. It is also called CELP (Coded Excitation Linear Prediction). In HVXC, no
adaptive codebook is used.
267. Wavetable synthesis: A synthesis method in which sound is created by simple manipulation of audio
samples, such as looping, pitch-shifting, enveloping, etc.
268. White Gaussian noise: A noise sequence which has a Gaussian distribution.
269. Width: The number of channels of data that an expression represents.
”.
In subclause 1.4.1 (Arithmetic operators), add the following definition:
„
ceil( ) Ceiling operator. Returns the smallest integer that is greater than or equal to the real-valued argument.
”.
In clause 1.4.6 (Mnemonics), definition of bslbf, replace
14 © ISO/IEC 2002 — All rights reserved

ISO/IEC 14496-3:2001/Cor.1:2002(E)
„
ISO/IEC 11172
”
with
„
ISO/IEC 14496
”.
In subclause 1.4.8 (Method of describing bit stream syntax), add
„
switch (expression) { If the condition formed by the comparison of
case const-expr: expression and const-expr is true, then the data
data_element; stream continues with the subsequent data
break; elements. An optionally break statement can be
case const-expr: used to immediately leave the switch, data
data_element; elements beyond a break do not occur in the data
} stream.
”.
In subclause 1.4.8 (Method of describing bit stream syntax), replace
„
The bitstream retrieved by the decoder is described in the syntax section of each subpart. Each data item in the
bitstream is in bold type. It is described by its name, its length in bits, and a mnemonic for its type and order of
transmission.
”
with
„
The bitstream payload retrieved by the decoder is described in the syntax section of each subpart. Each data
element in the bitstream payload is in bold type.
It is described by
� its name
� its length in bits, where "X.Y" indicates that the number of bits is one of the values between X and Y
including X and Y. "{X;Y}" means the number of bits is X or Y, depending on the value of other data
elements in the bitstream.),
� a mnemonic for its type and order of transmission.
Data elements forming a logic unit are encapsulated in data functions.
data_function ( ); Data function call.
data_function ( ) { Data function entity.
. . .
}
”.
At the end of subclause 1.4.8 (Method of describing bit stream syntax), remove the following paragraph:
„
The number of bits for each data element is written in the second column. "X.Y" indicates that the number of bits is
one of the values between X and Y including X and Y. "{X;Y}" means the number of bits is X or Y, depending on the
value of other data elements in the bitstream.
© ISO/IEC 2002— All rights reserved 15

ISO/IEC 14496-3:2001/Cor.1:2002(E)
”.
In subclause 1.4.8 (Method of describing bit stream syntax), remove
„
Definition of bytealigned function
The function bytealigned ( ) returns 1 if the current position is on a byte boundary, that is the next bit in the bit
stream is the first bit in a byte. Otherwise it returns 0.
”.
In subclause 1.5.1.1 (Audio object type definition), replace Table 1.1 (Audio Object Type definition) and the
subsequent notes as follows:
16 © ISO/IEC 2002 — All rights reserved

ISO/IEC 14496-3:2001/Cor.1:2002(E)
„
Tools/
Modules
Audio Object Type
Null 0
AAC main XX X X X XXX X X 2) 1
AAC LC X X X X XX XX X 2
AAC SSR X X X XX XX XX X 3
AAC LTP X X X X X X X X X X 2) 4
(Reserved) 5
AAC Scalable XX X XXX X X X XXX 6) 6
TwinVQ XXXXX X X 7
CELP X8
HVXC X9
(Reserved) 10
(Reserved) 11
TTSI X12
Main synthetic X X X 3) 13
Wavetable synthesis X X 4) 14
General MIDI X15
Algorithmic Synthesis X16
and Audio FX
ER AAC LC X X X X X X X X X X X 17
(Reserved) 18
ER AAC LTP X X X X X X X X X X X X 5) 19
ER AAC scalable X X X X X X XX XXX XX X 6) 20
ER TwinVQ X X X X X X X X 21
ER BSAC X X X X X X X X X X 22
ER AAC LD XX X X X XX X X XX 23
ER CELP X XXX 24
ER HVXC X X X X 25
ER HILN X X X 26
ER Parametric X X X X X 27
(Reserved) 28
(Reserved) 29
(Reserved) 30
(Reserved) 31
Notes:
1) The bit parsing function is mandatory on decoder site. However, the error detection and error correction
functions are optional.
2) Contains AAC LC.
3) Contains Wavetable synthesis and Algorithmic Synthesis and Audio FX.
4) Contains General MIDI.
5) Contains ER AAC LC.
6) The upsampling filter tool is only required in combination with a core coder.
“.
© ISO/IEC 2002— All rights reserved 17
gain control
block switching
window shapes - standard
window shapes – AAC LD
filterbank - standard
filterbank - SSR
TNS
LTP
intensity
coupling
MPEG-2 prediction
PNS
MS
SIAQ
FSS
upsampling filter tool
quantisation&coding - AAC
quantisation&coding - TwinVQ
quantisation&coding - BSAC
AAC ER Tools
ER payload syntax
EP Tool 1)
CELP
Silence Compression
HVXC
HVXC 4kbs VR
SA tools
SASBF
MIDI
HILN
TTSI
Remark
Object Type ID
ISO/IEC 14496-3:2001/Cor.1:2002(E)
In subclause 1.5.1.2.2 (AAC – Main object) after the first sentence, add the following sentence:
„
The restrictions of the AAC Main profile with respect to multiple programs and mixdown elements also apply to the
AAC Main object type.
”.
In subclause 1.5.2.1 (Profiles), replace
„
The Main Audio Profile is a rich superset of all the other Profiles, containing tools for natural and synthetic audio.
The Main Audio Profile is a superset of the other three profiles (scalable, speech, synthesis).
”
with
„
The Main Audio Profile is a superset of the scalable profile, the speech profile and the synthesis profile,
containing tools for natural and synthetic audio.
”.
In subclause 1.5.2.1 (Profiles), add at the end
„
In addition to the profile descriptions given above it is stated that AAC Scalable objects using wide-band CELP core
layer (with or without ER bitstream payload syntax) are not part of any Audio Profile.
”.
In subclause 1.5.2.2 (Complexity Units), replace
„
The following table gives complexity estimates for the different object types. PCU values are given in MOPS per
channel, RCU values in kWords per channel.
”
with
„
The following table gives complexity estimates for the different object types. PCU values are given in MOPS per
channel, RCU values in kWords per channel (with respect to AAC, channel refers to Main channel, e. g. the
channel of a SCE, one channel of a CPE, or the channel of an independently switched CCE).
”.
In subclause 1.5.2.2 (Complexity Units), in Table 1.3, replace
„
Sampling Rate
”
with
„
Sampling Rate Conversion
”.
18 © ISO/IEC 2002 — All rights reserved

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