[mythtv-users] OT: Multithreaded h264?

David Madsen david.madsen at gmail.com
Fri Nov 23 02:26:08 UTC 2007


> [root at red work]# mplayer  -lavdopts fast:threads=1 -vo null -ao null
> -nosound -benchmark 720p-x264-sample.mkv
> MPlayer dev-SVN-r24885-4.1.1 (C) 2000-2007 MPlayer Team
> BENCHMARKs: VC:  19.297s VO:   0.008s A:   0.000s Sys:   0.194s =   19.499s
>
> [root at red work]# mplayer  -lavdopts fast:threads=2 -vo null -ao null
> -nosound -benchmark 720p-x264-sample.mkv
> MPlayer dev-SVN-r24885-4.1.1 (C) 2000-2007 MPlayer Team
> BENCHMARKs: VC:  19.261s VO:   0.008s A:   0.000s Sys:   0.191s =   19.460s
>
> Unless I'm doing something wrong, can't say that it actually appears
> to have any benefit... wish it did..
>

The multithreading support for h264 will only work if the h264 stream
was encoded with slices enabled.  The multithreading code works by
sending each slice off to a different thread to be decoded rather than
a threaded pipelined approach.  Recent builds of the x264 encoder
don't use multiple slices by default any longer so it's quite possible
that your file only has once slice and will only be decoded by one
thread.

--David Madsen


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