[MPlayer-users] h.264 'slow motion' problem

Håkon Alstadheim hakon at alstadheim.priv.no
Mon Jan 12 02:02:06 CET 2009

Derek C wrote:
> Hi again Nico,
>> the easiest way is to add +8192 to the audio or video pids section...
> I can tell you immediately that by adding +8192 after the video pid it
> worked - just like that!
> This is obviously far better than my badness with the demux_ts.c file.
> I still have the other problem - the "slow motion" one.  I have tried many
> mplayer switches (including the "-demuxer lavf" one) but the problem
> remains.
> There are a number of people on an Irish [MythTV] mailing list seeing this
> problem too.  One person works for the national TV company and is sure
> that the H264 transmission is quite standard.
> The problem is this:
> Video appears to play at 1/2 speed - audio is the correct speed.
> I've left mplayer playing for some time (10 minutes perhaps) and I saw the
> following message repeated over and over (bytes increase in value on each
> iteration):
> "Too many video packets in the buffer: (4096 in 32138137 bytes).
> Maybe you are playing a non-interleaved stream/file or the codec failed?
> For AVI files, try to force non-interleaved mode with the -ni option."
> The computer is a P4 2.8ghz and top says that mplayer is using around 25%
> CPU time so it doesn't look like a problem there.
How about showing us the output on the terminal from an mplayer run ? 
That should tell us a bit about the signal you are seeing and hou 
mplayer interprets it. Awaiting that, it would be interesting to hear if 
the info below is of any help:

I also struggled with getting mplayer to play the DVB-T streams here in 
Norway. Short description of status here and the work-arounds I use: 
(I'm NOT using "-demuxer lavf")

- There is some basic problem with mplayer  not scanning far enough to 
find anything useful. If you are playing directly from the stream, just 
try again. If from a file use "-sb 1000000" and keep increasing by 
1000000 until you get something. There are switches for adressing this 
problem more directly. Hopefully someone more knowlegeable will speak 
up. :-)
- Interlaced h.264 content will confuse mplayers timing, -mc 2 will 
allow mplayer to move video frames around by 2 seconds, works well on 
the "video too slow" problem. (actually -mc 0.5 should suffice)
- the default codec (used to ?) not work, adding " -vfm ffmpeg" gets me 
better results. (I suppose this is an alternative to the suggested 
demuxer switch.
- just in case there actually is some kind of performance problem, I add 
" -lavdopts fast -framedrop "
- I also use "-vf pp=fd/fa ", though I can't remember why at the moment. 
Check the docs

spammers please send mail to finnesikke at alstadheim.priv.no 
Håkon Alstadheim

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