Introduction
Several part of MPEG 4 Structured Audio are not discussed in the
book. In this Appendix, we briefly describe these topics, and provide
a pointer to the part(s) of the standards document (FDIS ISO/IEC
14496-3:1999(E), edited by Eric Scheirer) that
explains the topic.
The uncovered topics are listed on the right panel. Several
of these topics concern language features not included in
sfront, such as AudioFX support and SASBF synthesis.
The other topics on the right panel are standards-oriented issues,
such as the binary layout of an MP4 file, that is not usually
necessary knowledge for SAOL programmers.
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Uncovered Topics and
FDIS Page Numbers
Language Features
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sasbf (p. 52, 107) An atomic element in expressions,
that implements a sample-bank based synthesizer algorithm. Its
primary purpose in life is to support Object 2 MP4-SA decoders,
which don't use SAOL and SASL. Not in sfront.
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AudioFX elements (p. 56, 114). SAOL can be used in other
parts of MP4 as a support language for effects processing. The
standard names position, direction,
listenerPosition, listenerDirection, minFront,
maxFront, minBack, maxBack, and params
support this application. Control drivers in sfront are
able to support these variables, but none do at present.
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fx_speedc core opcode (p. 95) A core opcode for
changing the sampling rate of an input_bus. Not supported
in sfront.
Standards Issues
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Binary MP4-SA Files (p. 16, 106, 116). How to read and write the
MP4 binary encoding.
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Decoding Process (p. 21). Exact normative description of
how a SAOL program starts up, and how an orchestra cycle
executes.
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Random Access (p. 131). How to write SAOL and SASL so that the
audio can be "fast-forwarded and reversed" easily.
Return to:
Appendix Cover Page
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