[Mp4-tech] [Audio] Querries on Integer implementation of SBR Decoder

[Andreas Schneider]

Dear Dattaguru,
MPEG-4 conformance (ISO/IEC 14496-4) specifies criteria that conforming 
decoders have to meet. These criteria apply to any implementation, no 
matter whether it is based on integer or floating point math.
If you want to implement an HE-AAC decoder, it has to fulfill conformance 
for the AOTs AAC-LC and SBR. The SBR conformance testing procedure is 
designed to neglect differences that originate from the underlying AAC-LC 
decoder, so you don't have to worry about that.
Hope that helps,
Andreas
mp4-tech-bounces lists.mpegif.org wrote on 11/10/2023 07:43:38 AM:
> Dear All,
> 
> I want to know some information on integer
> implementation of SBR decoder.
> 
> For the QMF analysis filter, input is the output of
> the windowing ( output of AAC ). 
> Integer implementation of AAC decoder will have an
> error upto 2 bits (output of windowing) or may be more
> also!!!. 
> 
> As QMF analysis filter consists of lots of cumulative
> additions and multiplications,  the small difference 
> in the input ( output from windowing)  will result in
> large error at the output of the analysis filter.
> Hence, there will be a huge difference at the output.
> 
> 
> Could you please let me know 
> 1.  Is there any specific RMS/LSB error values
> specified for integer implementation of SBR decoder by
> Coding technologies? 
> 2. Is there any specific implementation for integer?
> 
> 
> Thanks and regards,
> Dattaguru
> 
> 
> 
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--
Andreas Schneider, Research Engineer
Coding Technologies GmbH
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