[vlc-devel] [PATCH] codec: avcodec: no FRAME threading on unknown/low framerate

Francois Cartegnie fcvlcdev at free.fr
Wed Aug 22 17:35:13 CEST 2018

Le 21/08/2018 à 21:06, Rémi Denis-Courmont a écrit :
> Le tiistaina 21. elokuuta 2018, 19.27.46 EEST Francois Cartegnie a écrit :
>> fixes always late frames due to threading delay
> Unknown rate does not imply low rate.

Unfortunately there's no way to guess frame rate in those cases without
buffering (ie, make things worse).

I don't know containers without frame rate info, or containing H26x not
providing frame rate (VUI) outside of RTSP use case.

> Given that we cannot safely enable hardware decoding with unknown rate, 
> blocking threaded decoding as well seems rather insane.

Well, frame threaded, not slice threaded.

> In other words, this might work around some bugs but it will also break stuff 
> that was working so far.

I never seen an explanation of SLICE vs FRAME threading performance
There's only known broken/blacklisted ones with some codecs.
The slice threading fallback can be limited to RTSP by tagging es fmt
with a low delay flag.

Francois Cartegnie
VideoLAN - VLC Developer

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