[FFmpeg-user] Equivalent parameter for CRF in hevc_videotoolbox

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed Jan 16 02:46:34 EET 2019

2018-12-05 15:54 GMT+01:00, 桃源老師 <xanadu6291 at dream.jp>:

> I recently noticed that ffmpeg can use hardware acceleration via
> videotoolbox on Mac.

Since 2016;-)

> Before above discovery, I use the command like as follows:
> ffmpeg -i DR08.ts -c:v libx265 -preset medium -crf 23 -tag:v hvc1 -vsync 1
> -c:a copy -bsf:a aac_adtstoasc DR08.mp4
> Now I noticed that CRF does not work on hevc_videotoolbox codec.  Based on
> very rough trying, -b:v only changes quality of encoded video.
> So my question is is there equivalent parameter for CRF in hevc_videotoolbox
> codec or not.  In another word, how to set quality of hardware acceleration
> of video?

Only constant bitrate (or whatever the Apple driver does with the
bitrate, could be adaptive bitrate or similar) is currently supported
for the videotoolbox encoder.

Sorry for the late answer, Carl Eugen

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