ISO/IEC 14496-4:2004/Amd 29:2008

INTERNATIONAL ISO/IEC
STANDARD 14496-4
Second edition
2004-12-15
AMENDMENT 29
2008-07-01


Information technology — Coding of
audio-visual objects —
Part 4:
Conformance testing
AMENDMENT 29: Symbolic Music
Representation conformance
Technologies de l'information — Codage des objets audiovisuels —
Partie 4: Essai de conformité
AMENDEMENT 29: Conformité de la représentation musicale
symbolique




Reference number
ISO/IEC 14496-4:2004/Amd.29:2008(E)
©
ISO/IEC 2008

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ISO/IEC 14496-4:2004/Amd.29:2008(E)
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ISO/IEC 14496-4:2004/Amd.29:2008(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
Amendment 29 to ISO/IEC 14496-4:2004 was prepared by Joint Technical Committee ISO/IEC JTC 1,
Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia
information.


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ISO/IEC 14496-4:2004/Amd.29:2008(E)
Information technology — Coding of audio-visual objects —
Part 4:
Conformance testing
AMENDMENT 29: Symbolic Music Representation conformance
In Clause 2 “Normative references” add:
ISO/IEC 14496-23:2008, Information technology — Coding of audio-visual objects — Part 23: Symbolic Music
Representation
Add a new Clause 11 “Symbolic Music Representation”:
11 Symbolic Music Representation
11.1 General
This clause specifies how tests can be designed to verify whether bitstreams and decoders meet
requirements specified in ISO/IEC 14496-23. In this part of ISO/IEC 14496, encoders are not addressed
specifically. An encoder may be said to be an ISO/IEC 14496-23 encoder if it generates bitstreams compliant
with the syntactic and semantic bitstream requirements specified in ISO/IEC 14496-23.
Procedures are described for testing conformance of bitstreams and decoders to the requirements defined in
ISO/IEC 14496-23. Given the set of characteristics claimed, the requirements that must be met are fully
determined by ISO/IEC 14496-23. This clause summarizes the requirements; cross references them to
characteristics, and defines how conformance with them can be tested. Guidelines are given on constructing
tests to verify bitstream and decoder conformance. In addition, some test bitstreams implemented according
to those guidelines are provided as an electronic annex.
Symbolic Music Representation (SMR) objects allow modeling the visual aspects of a music score, and audio
information or annotations related to the music piece.
SMR includes the definition of XML schemas (for representing music symbols composing the music score and
describing the rules to be used for placement of music symbols) and additional binary information (for
presenting the music score synchronously with a multimedia scene).
This clause describes criteria to test SMR Conformance for bitstreams and decoders.
11.2 SMR Conformance testing
11.2.1 AudioSpecificConfig characteristics
The bitstream provider may apply restrictions to the following parameters of the AudioSpecificConfig:
1) audioObjectType: AOT 40 (uncompressed/Gzip-ed XML) or AOT 41 (BiM encoded XML)
2) numberOfParts: the number of parts composing the score
3) notationFormat: can be CWMN, BRAILLE, SPOKENMUSIC, OTHER
4) codingType: can be XML, GZIP, BIM
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ISO/IEC 14496-4:2004/Amd.29:2008(E)
AccessUnit characteristics
The bitstream provider may apply no restrictions to any parameters of the bitstream
11.2.2 Procedure to test Bitstream Conformance
According to the restriction on the codingType field, the decoder shall be tested first for the exact bitstream
decoding from binary format to the corresponding xml files.
The Conformance Bitstreams described later shall be decoded using the codingType(s) supported by the
decoder under test. To be called an ISO/IEC 14496-23 SMR decoder, the decoder shall provide an output
where xml information (SM-XL, SM-FL) is identical to the reference file provided by ISO for the same
bitstream.
Please note that a decoder, for efficiency or other reason, may be implemented in a way that a textual xml
representation is not necessary to process information. Nevertheless, for testing purposes, a textual xml file
dumping is required.
11.2.3 Decoder characteristics and computational complexity
The SMR Decoder, after having decoded the binary stream, produces a corresponding rendering (graphics,
audio or other) and periodically refreshes it according to dynamic updates that may come from access units or
user interaction (through the MusicScore node).
A very few points in the decoding process may need a meaningful amount of computing resources (both CPU
and/or memory) according to the specific implementation: the generation of a view, and some of the most
typical updates (transposition, jump to, etc.).
Possible features which may be used to characterize from this point of view the complexity of a bitstream are:
the number of symbols present for a certain unit of time, the number of dynamic operations on the score (such
as transposing, etc.), and memory allocation.
At this time no needs were identified to define different complexity levels but in case the music industry needs
them the document will be amended.
11.3 Procedure to test SMR decoder conformance
SMR Decoder conformance must be tested in terms of real-time decoding capabilities, and quality
assessment of its rendering in terms of graphics, or audio when required.
The rendering of a score must obey to important rules, while some additional detail belongs to the domain of
subjective (or style) preferences, and then should not be assessed by conformance testing. For a more
comprehensive understanding of the required formatting and rendering rules, see ISO/IEC 14496-23,
Clause 11.
Graphical features that shall be considered for conformance testing are:
• correct vertical note/rest alignment
• logical articulation placement, e.g.
o text and lyrics placement
o no overlap of symbols
• necessity to display all the required symbols
• possible skipped (not displayed) symbols
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ISO/IEC 14496-4:2004/Amd.29:2008(E)
To be called an ISO/IEC 14496-23 SMR decoder, the decoder shall provide an output that does not
meaningfully diverges from the reference output provided by ISO for the several test bitstreams described
below. Meaningful divergence means that once considered the small stylistic differences that may come from
the usage of different font characters, different horizontal spacing, and different view formatting when allowed,
the output rendered score still presents visually evident differences (that means, a human expert can detect
them) from the reference output in terms of the features listed above. This shall be true for all test bitstreams
with no exception.
11.4 Description of the SMR Conformance Bitstreams
For each of the conformance bitstreams shortly described in this clause, ISO provides in form of electronic
attachment the following files:
• An mp4 file with flat xml information (stxx-xml.mp4)
• An mp4 file with gzip-ped xml information (stxx-gzip.mp4)
• An mp4 file with xml information coded through BiM (to be used when supported) (stxx-bim.mp4)
• Reference xml files (in directory stxx.xsm)
• Reference output with short description (MS Word
...