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

Sven C. Dack sven.c.dack at sky.com
Sat Sep 10 20:55:26 EEST 2016

On 10/09/16 18:35, Andy Furniss wrote:
> Andy Furniss wrote:
>> With gstreamer 1080p I can get around 350 fps testing like -
>> gst-launch-1.0 -f ximagesrc use-damage=0 startx=0 starty=0 endx=1919
>>  endy=1079 num-buffers=5000 ! queue ! videoconvert !
>> video/x-raw,framerate=500/1,format=BGRx ! fakesink Setting pipeline
>> to PAUSED ... Pipeline is live and does not need PREROLL ... Setting
>> pipeline to PLAYING ... New clock: GstSystemClock Got EOS from
>> element "pipeline0". Execution ended after 0:00:14.205120141 Setting
>> pipeline to PAUSED ... Setting pipeline to READY ... Setting pipeline
>> to NULL ... Freeing pipeline ...
>> 5000/14.205120141 = 351.98....
>> Of course I don't know if that's "real" as such.
> 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.
> ffmpeg is not using xcb for this test and like this both ffmpeg and
> gstreamer are using XShmGetImage.
> With gstreamer all calls to __memcpy_sse2_unaligned are from X
> with ffmpeg half are from X and half ffmpeg.
> OK I think, maybe the test was flawed, so I changed fakesink to filesink
> location=/mnt/ramdisk/out.bgr0 where ramdisk is tmpfs. Sure enough it's
> slower = 188fps which is more like ffmpeg (179 fps with -f null -).
> Unfortunately if I force ffmpeg to really output to tmpfs using
> -f rawvideo -y /mnt/ramdisk/out.bgr0 I only get 68fps so I am still slower.
> FWIW -f rawvideo -y /dev/null gives 90fps.
I'd be more interested in grabbing the desktop synchronous to the display 
refresh rate at this point. 60Hz is a key mark, going above it not so much. What 
would be the next mark anyway? 100Hz?

More information about the ffmpeg-devel mailing list