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

[Reimar Döffinger]

On Wed, Sep 18, 2013 at 12:41:26AM +0200, Reimar Döffinger 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.
> 
> Signed-off-by: Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> ---
>  Changelog                   |  2 ++
>  libavcodec/ffv1dec.c        | 50 ++++++++++++++-------------------------------
>  libavcodec/internal.h       | 11 ++++++++++
>  libavcodec/proresdec2.c     |  6 +-----
>  libavcodec/proresdec_lgpl.c |  8 +++-----
>  libavcodec/utils.c          | 36 ++++++++++++++++++++++++++++++++
>  libavcodec/vp56.c           |  9 ++++----
>  7 files changed, 73 insertions(+), 49 deletions(-)

My hope was that this variant with a special function might be
more maintainable and less code in the codecs.
On the other hand it is a bit more obfuscated...