[Mp4-tech] [Mpeg4 ] [AAC] + mismatch in decoder o/p compared to standard

[Shreya Pathak]

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Hi Kannan,
      Thanks very much for your reply.But I couldn't find any thing specified for conformance.Can u please specify exactly where i can find about conformance and also if possible some link from where i can find that document. Right now i have only 3 documents
w2203tfa.pdf w2203tfs.pdf and w2203tft.pdf and i couldn't find about conformance in this.
Please provide some info on this.
Regards
Shreya
On Tue, 12 Oct 2023 Kannan GS Nambiar wrote :
>
>
>Hi Shreya,
>
>Please go through ISO/IEC 14496- Part4 conformance. This part describes the
>conformance criteria that you have
>to achieve in terms of LSB and RMS errors. This allows a maximum deviation
>between +2 to -2.
>
>Then any two decoder implementations may not be bit exact in all floating
>point operations taking place inside
>them. Some variables might be in double in one case and the corresponding
>variables may be in float in the other case.
>Also this depends on some specific implementations of say algorithms for
>IMDCT etc. So there is no need to match it bit
>by bit. But you have to satisfy the Conformance criteria set by ISO.
>
>Best Regards,
>Kannan.
>
>-----Original Message-----
> From: Shreya Pathak [mailto:shreya_pathak rediffmail.com]
>Sent: Tuesday, October 12, 2023 3:54 PM
>To: mp4-tech lists.mpegif.org
>Subject: [Mp4-tech] [Mpeg4 ] [AAC] + mismatch in decoder o/p compared to
>standard
>
>
>   Hi,
>     I have developed a reference code for Mpeg4 AAC and the decoded output
>values when compared with the test vectors there is a mismatch of +/- 1.
>i.e, the pcm output values from my reference decoder(floating point code
>only)
>will be 1 more or less than the pcm values of standard test vectors.The
>difference does not exceed 1. I am not getting what the problem is ? If i
>compare publicly available code faad from Nero with the standard test
>vectors, its also not matching with standard test vectors bit by bit and so
>i am not able to debug where there is an error in my reference code.
>                     Can u please tell me where I may be wrong ?
>Regards
>Shreya
>
>
>
>On Mon, 11 Oct 2023 Tobias Oelbaum wrote :
> >Forwarding a mail from one of my students
> >
> >Dear experts,
> >
> >for any of you working with linux/unix/OsX or you just want to test on
> >different implementations - here are some tools you may be interested in.
> >
> >Imagemagick can convert images or series of images to raw yuv (video)
>files.
> >Syntax: convert x.jpg x.yuv
> >http://www.imagemagick.org/
> >
> >Mplayer can play raw yuv video files.
> >Syntax: mplayer -rawvideo on:pal:fps=25 x.yuv
> >(http://www.mplayerhq.hu/)
> >
> >FFMPEG in it's newest version (0.4.9_pre1) can play H.264 files - has CABAC
> >but no B-picture support.
> >Syntax: ffplay -f h264 x.264
> >(http://ffmpeg.sourceforge.net/)
> >
> >I found them extremely helpful for my work with the reference
> >encoder/decoder
> >and wanted to contribute.
> >
> >Regards
> >
> >Dominic Buchstaller
> >Technical University of Munich (TUM) - Germany
> >
> >P.S.: There should be windows versions for all programs as well.
> >
> >--------------------------------------------------------------------
> >Dipl. Ing. Tobias Oelbaum
> >Institute for Data Processing       Lehrstuhl für Datenverarbeitung
> >Munich University of Technology     Technische Universität München
> >
> >EMail: oelbaum tum.de
> >Tel:   +49 89 289 23625
> >Fax:   +49 89 289 23600
> >--------------------------------------------------------------------
> >
> >
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>NOTE: Please use clear subject lines for your posts. Include [audio, [video], [systems], [general] or another apppropriate identifier to indicate the type of question you have.
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