[FFmpeg-devel] [PATCH] Make decoding alpha optional for some codecs.

compn tempn at twmi.rr.com
Wed Sep 18 12:04:59 CEST 2013

On Wed, 18 Sep 2013 08:37:51 +0000, Paul B Mahol wrote:
>On 9/17/13, Reimar Doeffinger <Reimar.Doeffinger at gmx.de> wrote:
>> For codecs where decoding of a whole plane can simply
>> be skipped, we should offer applications to not decode
>> alpha for better performance (ca. 30% less CPU usage
>> and 40% reduced memory bandwidth).
>> It also means applications do not need to implement support
>> (even if it is rather simple) for YUVA formats in order to be
>> able to play these files.
>> Tested by manually hacking avcodec_default_get_format,
>> suggestions for how to test in FATE welcome.
>Why you think this change is so important that should be

it sounds similar to other cpu saving decoder features that ffmpeg has.
like 'skiploopfilter' or 'skipnonref' or 'fast'.

do those features take similar amounts of code?

do you think skipping alpha could be done in a simpler way?

30% is a lot of speedup...


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