[FFmpeg-devel] suggestion for expanding audio bitdepth support in libav/ffmpeg

madshi dear
Sat Jan 19 15:08:20 CET 2008


I've been told by different people that sooner or later ffmpeg is supposed
to get support for multiple audio bitdepths with all the bells and whistles.
But it seems to be a very big change and so it gets pushed back, 
respectively
nobody is daring to take over this job. Please correct me, if I'm wrong 
on this.

Here comes a suggestion on a first step to the final goal which should be
much easier to realize without breaking anything:

--------

CURRENT STATE:
As far as I understand things, currently ffmpeg calls the audio decoders
and expects 16bit integer samples from them. Other formats are not
supported by ffmpeg.

ULTIMATE SOLUTION:
ffmpeg can handle any audio format and every decoder can output what
it wants.

INTERMEDIATE STEP:
We let the decoders output whatever they want but add an intermediate
step between the decoders and ffmpeg which converts every audio
format to 16bit integer. This way ffmpeg can stay as it is. And the
decoders can in the beginning also stay as they are without breaking
anything. But this would allow us to change one decoder after the other
to output the most optimal sample format and bitdepth without having
any effect on ffmpeg. Furthermore if there is a central audio conversion
routine to 16bit integer, it would also be rather easy to add proper
TPDF dithering, which is missing right now, I believe.

--------

What do you guys think?

I have to add that I'm not up to the task of doing the work. I just wanted
to throw my thoughts at you.

madshi.




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