Strange performance results
|Reported by:||zezinho||Owned by:|
|Blocking:||Reproduced by developer:||no|
|Analyzed by developer:||no|
Summary of the bug:
Encoding with VAAPI is much slower if sound is converted. Launching another ffmpeg dedicated to the sound conversion gives much better results.
The test was done with 9th generation Intel HD500 in a Celeron N3350 and a 1080p@24 and 18Mb/s file.
With the example below, I get 60fps so it is 2.42x speed. Removing the acodec copy option, it is converted to vorbis, speed drops to 42fps (1.41x).
The strange point is that launching another simultaneous ffmpeg to drops the video and converts to vorbis, I get normal speed for this CPU : 5.5x and the other ffmpeg keeps at 2.42x.
So it seems using VAAPI along with Vorbis slows down both codecs.
How to reproduce:
% ffmpeg \ -hwaccel vaapi \ -vaapi_device /dev/dri/renderD128 \ -i input.mkv \ -vf 'format=nv12,hwupload,scale_vaapi=w=1366:h=768' \ -vcodec h264_vaapi \ -acodec copy \ -qp 23 \ output.mkv ffmpeg version 3.2.4 built on gcc 5.4.0 (Mageia 6 package)