[FFmpeg-devel] [RFC] ffmpeg: default to single thread when hwaccel is active

[Timo Rothenpieler]

On 29.09.2021 19:31, Dennis Mungai wrote:
> On Wed, 29 Sept 2021 at 20:22, Timo Rothenpieler <timo at rothenpieler.org>
> wrote:
> 
>> On 29.09.2021 19:17, Dennis Mungai wrote:
>>> A potential downside to this would be on QSV's side, which needs at least
>>> 2  threads to prevent dead-locking, see
>>>
>> https://github.com/Intel-Media-SDK/MediaSDK/blob/master/_studio/mfx_lib/scheduler/linux/src/mfx_scheduler_core_ischeduler.cpp#L90-L93
>>
>> Is that even controlled by the avcodec threads parameter?
>> I can't find any occurrence of "numberOfThreads" anywhere in the entire
>> codebase.
>>
>>
> See this patchwork:
> https://patchwork.ffmpeg.org/project/ffmpeg/patch/20210408070929.860244-1-haihao.xiang@intel.com/
> Submitted  by Haihao Xiang, CC'ed herein.

That almost makes me think we'd need a per-hwaccel default of the thread 
count.
Preferably not hacked as hard coded list into ffmpeg.c
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