[Mp4-tech] MPEG-2 conformance

[Manish]

Hi All,
I have few queries as follows
1. I have downloaded MPEG-2 reference software from site
http://standards.iso.org/ittf/PubliclyAvailableStandards/. The software has
two audio decoders MPEG-2 LSF (low sampling frequency decoder) and MPEG-2 MC
(Multi-channel decoder). Can anybody tell me MPEG-2 audio decoder should
include both LSF and MC configuration, or only LSF, or only MC configuration
is sufficient to be called as MPEG-2 audio decoder?
2. The MPEG-2 LSF in the reference software supports decoding of all 3
layers i.e. Layer 1, 2 and 3. But MPEG-2 MC decoder in reference software
supports only layer 1 and layer 2 decoding.  Can anybody guide from where
can I get MPEG-2 MC layer 3, decoder?
3. I have downloaded MPEG-2 reference vectors/test streams from
http://standards.iso.org/ittf/PubliclyAvailableStandards/ISO_IEC_13818-4_200
4_Conformance_Testing/Audio/
The link has document audectst which specifies conformance criteria for the
decoder. The conformance criteria specifies absoulute difference and RMS
difference threshold (relative to full scale for decoder) to be used for
testing of computational accuracy of the MPEG-2 decoder. It explains these
thresholds with 24 bit precision reference stream, which is supplied sine
sweep (20Hz-10kHz) with an amplitude of -20dB relative to full scale. It
also specifies that if decoder output has precision lower than 24 bits then
it should be zero padded to get 24 bit precision and then used for
conformance testing. Except for test steam 35 which is sine sweep
(20Hz-10kHz) rest all test streams have 16 bit precision. So when I use 16
bit conformance criteria i.e absolute difference and RMS difference
threshold relative to 16 bit precision MPEG-2 MC reference decoder software
fails the criteria for all test streams as the RMS difference threshold is
very small .28. For test35 stream 24 bit conformance criteria is applied
MPEG-2 MC decoder passes the conformance. While MPEG-2 LSF decoder not only
passes criteria but its decoded output identical to reference streams. Can
anybody tell me that only test35 stream should be used for accuracy/
conformance test / compliance? Or should the 16 bit  references should be
zero padded for 24 bit precision and then used for conformance/ accuracy
test?
Regards
Manish
Regards
Manish
http://www.patni.com
World-Wide Partnerships. World-Class Solutions.
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