[Libav-user] Speex encoding difference only in the very last encoded frame

[Joe Flowers]

Thank you Nicolas! That is very helpful!




On Tue, Aug 20, 2013 at 6:18 AM, Nicolas George <
nicolas.george at normalesup.org> wrote:

> Le duodi 2 fructidor, an CCXXI, Joe Flowers a écrit :
> > When I encode the same audio file with a program I am writing that uses
> > libavcodec I get a 26,372 byte Speex encoded file - FileB. BUT, 9 bytes
> in
> > the middle of the last 38 bytes of encoded data are different between
> the 2
> > encoded files (FileA and FileB). All of the other bytes are exactly the
> > same between the two encoded files.
>
> I would suggest to add a dump of each frame before encoding, in both your
> program and ffmpeg (or just in libavcodec). I suspect something in the
> padding / very end of the last frame may be different.
>
> > What makes this weirder to me is that if I decode my Speex encoded file
> > (FileB) with the other part of my program that uses libavcodec I get the
> > EXACT same decoded file contents and length as I do if I decode the
> > FFMPEG-encoded file (FileA) with FFMPEG.
>
> That would be consistent with what I suspect: the difference you see would
> manifest on the next decoded frame if there was one.
>
> Regards,
>
> --
>   Nicolas George
>
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