[FFmpeg-devel] [PATCH 1/2] libavcodec/qsvenc.c delay in 1 microsecond replaced to more appropriate 500 microseconds

Ivan Uskov ivan.uskov at nablet.com
Tue Jul 28 17:30:56 CEST 2015

Hello All,

The attached patch replaces 1 microsecond delay to 500 microsecond for
case when MFX library does return MFX_WRN_DEVICE_BUSY status.
In general this warning never appears for simple encoding or
transcoding session because GPU so fast so almost always not busy and
any delay value just not executes.
But for heavy transcoding tasks for example, when several QSV sessions
are running simultaneously the using of 1-microsecond delay may be
result of 1000 iterations per each frame. 
So here possible a paradoxical case when GPU loading also loads CPU by dummy tasks.
Official MFX/QSV samples by Intel are use 1 millisecond (i.e. 1000
microseconds) everywhere where MFX_WRN_DEVICE_BUSY does appear.
So 500us is much more optimal value than 1us.


Best regards,
 Ivan                          mailto:ivan.uskov at nablet.com
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