[FFmpeg-devel] Patch review request: 10bit DNxHD decoding support

Maxim max_pole
Sat Mar 12 14:57:39 CET 2011

Joseph Artsimovich schrieb:
>> I'm currently working on a support for the 10bit IDCT (both SSE2 and Altivec).
>> Some minor modifications (regarding rounding constants) of the existing
>> functions (idct_altivec.c and idct_sse2_xvid.c) are required.
>> There are two minor issues:
> Have you already decided on how are you going to expose them via DSPContext, API wise?

No, I'm going to post the adapted code and let the others (having more
experience on dsputils) decide how that should be called.

I assume we have to add a new algo constant like that:

idct_algo = FF_IDCT_EXT

and then let dsputil activate the proper transform code for us...

Another challenge will be to deal with pre- and postprocessing requiered
by some video codecs (DNxHD etc.) like adding bias value, clipping final
pixels and shifting them to fit the desired output format.
Doing such things in a separate step spends alot of additional
computation time for temporary loading/storing data. Maybe it makes
sense to distribute that transform as macro so the compiler can
eliminate unnecessary load/store code during optimizations...

Best regards

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