[vlc-devel] commit: Decreased priority of libmpeg2 decoder below avcodec. ( Laurent Aimar )

[Rémi Denis-Courmont]

Le samedi 30 janvier 2010 22:23:56 Måns Rullgård, vous avez écrit :
> "Rémi Denis-Courmont" <remi at remlab.net> writes:
> > Le samedi 30 janvier 2010 21:26:42 Måns Rullgård, vous avez écrit :
> >> "Rémi Denis-Courmont" <remi at remlab.net> writes:
> >> > Le dimanche 24 janvier 2010 16:28:59 git version control, vous avez
> >> > écrit
> >> >
> >> >> vlc | branch: master | Laurent Aimar <fenrir at videolan.org> | Sun Jan
> >> >> 24 15:26:09 2010 +0100| [7ad6676d1b65a222682dc814782b57de798c068c] |
> >> >> committer: Laurent Aimar
> >> >>
> >> >> Decreased priority of libmpeg2 decoder below avcodec.
> >> >
> >> > On second thought, that really does not make sense.
> >> >
> >> > libmpeg2 provides a strict subset of the functionality of
> >> > libavcodec, in terms of what its pf_activate function
> >> > accepts. Reducing its priority essentially turns it into dead
> >> > code. configure --disable-libmpeg2 would have the same in a much
> >> > more efficient manner.
> >>
> >> Did you ever figure out why vlc+libavcodec was slower on the N900?
> >
> > I haven't really tried. And while you can install oprofile, I am not at
> > all familiar with the tool.
> >
> > Laurent hypothesized that it could be the packetizer VLC puts in
> > front of lavc but not libmpeg2.
> 
> There's only one way to find out: run the profiler...
> 
> Does vlc have a decode-only mode?  Profiling is easier if the display
> overhead is removed, and I don't have X running on my ARM boards.

$(vlc -V dummy) would convert the decoded pictures into entropy of the 
thermodynamic kind. This is not to be confused with $(vlc --no-video) which 
would not decode the video ES.

-- 
Rémi Denis-Courmont
http://www.remlab.net/
http://fi.linkedin.com/in/remidenis