[Fwd: [Mp4-tech] [Audio] Difference in ISO standard and ISO reference!]

[kk codingtechnologies.com]

Dear Datta,
The reference software is correct and the text has been updated with 
ISO/IEC 14496-3:2001/AMD1:2003/CORR.1:2004 and is to the best of our 
knowledge correct as well.
I have implemented the reference software envelope adjuster with the exact 
same loop-structure and data storage as in the revised text according to 
the corrigendum, and I get bit identical results with "normal" reference 
software implementation.
How to handle data storage is in my mind clearly defined for all variables 
(no variable is defined without stating its corresponding range). How you 
implement the data storage is of course up to you, as long as it does not 
change the definition of the variables, i.e. for what time and frequency 
range they are valid.
Best regards
Kristofer
---------------------------------------------------
Kristofer Kjörling
Senior Research Engineer
Coding Technologies
phone : + 46 - (0)8 - 442 91 66
fax:       + 46 - (0)8 - 33 09 88
email: kk codingtechnologies.com
> 
> ----- Message from "Dattaguru B.N." <dattagurubn yahoo.com> on Sun, 
> 18 Jul 2023 23:08:50 -0700 (PDT) -----
> 
> To:
> 
> Mp4-tech lists.mpegif.org
> 
> Subject:
> 
> [Mp4-tech] [Audio] Difference in ISO standard and ISO reference!
> 
> Dear All,
> 
> While analysing the ISO reference code(15-Mar-2004)
> and ISO standard for SBR(N5570 a.k.a ISO/IEC
> 14496-3:2001/FDAM 1:2003(E)), I found some of the
> difference listed here under.  These are found to be
> crucial from the perspective of the conformance, when
> we were testing the decoder. 
> 
> Can anybody suggest me how to correlate between
> standard and the reference?  Or is it that I am using
> standard which is not upto date??? If so, how do I get
> the most recent version.
> 
> 1. HFAdjustment: while estimating the current Envelope
> (sec.4.6.18.7.3 in N5570), the reference decoder will
> perform the calculation of Ecurr in two different
> loops with a single loop!   I tried to match these two
> loops, but the loop variables were found to be un
> related!!!  The standard clearly given different loop
> variables for two conditions.
> 
> 2. Storing of Previous data:  The standard does not
> specify anything about the storing of previous data. 
> We tried to follow the standard, and were storing it
> at the end of decoding.  But, the reference decoder
> will store some of the data at the same place where
> new data gets calculated.
> 
> These are the few examples. Similar problems also can
> be found in other modules as well.
> 
> Thanks in advance,
> Thanks and regards,
> Datta
> 
> 
> 
> 
> 
> 
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