[mythtv-users] MythTV very unforgiving about mpeg2 errors

Mario Limonciello mario.mailing at gmail.com
Sat Apr 1 22:27:08 UTC 2006


Ever since I received my HD5000 card from the first batch, I have had
problems with every myth version i've worked with.

I use spdif for pass thru on my audio, and I will run into problems
where my receiver doesn't seem to handle problems in the audio stream,
or maybe myth is putting out a junky stream when saturated with cpu
usage.  The receiver switches out of DD mode back into PCM about 3 times
a second while this is happening.

I have done a little comparison on the same recording. 
This is recording is 1080i with 5.1 AC3 track attached.  I use component
out on my Nvidia 6200 driving my ancient TV at 800x600.  This is an
AthlonXP 3000+ with 512 ram and ran over a netboot.

Myth always complains about 10 seconds into it and at various other
unimportant areas, but every other video player I've experimented with
seems to handle it fine.

CPU Usage wise,

xine
45-50 xine
45-50 X

vlc
30-40 vlc
10-20 X

mplayer (libmpeg2)
55 mplayer
40 X

mythtv (ffmpeg)
50-60 mythtv
40-50 X

VLC is a hands down winner for playing the file, especially since it
gracefully handles any areas in the file that have problems and
continues to chug thru.

All of my options for all of these other media players are default
options, except for spdif pass thru on each.

As for myth settings, I have
Aggressive sound card buffering
Deinterlacing with Kernel turned on
Standard (ffmpeg) video output

I've experimented at seem to have better luck on some recordings with
libmpeg2 and have better luck with some recordings, but not all of them.

XvMC isn't an option really, since the nvidia bug for XvMC not working
is still existing.  I'm waiting for the next nvidia release to hope for
XvMC support. 


My big question now is, why is myth so unforgiving about these stream
problems, yet all the other big video players handle them fine?  Is it
just because myth is so much more pegged for CPU when playing back?  If
thats the case, why is myth so much more pegged for CPU?




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