[FFmpeg-devel] adding RGBA and BGRA to nvenc.c

Andy Furniss adf.lists at gmail.com
Sat Sep 10 21:48:09 EEST 2016

Nicolas George wrote:
> Le quintidi 25 fructidor, an CCXXIV, Andy Furniss a écrit :
>> Looking into this more with sysprof it seems with this test
>> gstreamer is twice as fast because it doesn't copy from shm but
>> ffmpeg does.
>> Of course I may be misunderstanding, but >90% load according to
>> sysprof is __memcpy_sse2_unaligned.
> Can you detect what call to memcpy() in the ffmpeg code is
> responsible for this?

Not with sysprof unfortunately.

> I had an inkling that it was about the packet -> frame conversion,
> but it seems rawdec does the right thing in this particular case.
> Still, I suggest you add a quick debug av_log() in
> libavcodec/rawdec.c to check that need_copy is false.

I shall have go later this evening.

> Also, did you have a look at my last mail on the topic:
> http://ffmpeg.org/pipermail/ffmpeg-devel/2016-September/199156.html
> about the speed difference between xcb and xlib?

I did and thanks for taking an interest - as I don't really know much
about the code I thought that one was more for Carl Eugen :-)

But yes I get the version I am currently testing is unsafe - just it
seems to be more like gstreamer in using XShmGetImage so I thought the
sysprofs would be easier to compare.

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