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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