[mythtv-users] mpeg2 running 33%-50% too fast

Justin Mazzola Paluska jmp at MIT.EDU
Thu Jun 21 21:48:47 UTC 2007


Hi!

We have a MythTV .20 box with a PVR-500 installed in it, running on
Debian testing.  Recently, we’ve started to have strange problems with
the MPEG2 files that MythTV produces.  They play fine in mythfrontend
and in mplayer, but exhibit some strange speedup 25s into the file
when played in VLC.  That is, the first 25s of the file play just
fine, then the rest of the file plays 33%-50% faster than it should.
The video and audio stay in sync, though the audio goes up in pitch.
Unfortunately, we use VLC to transcode the MPEG2 files to mp4 to
eventually pass them to Darwin Streaming Server on a Mac.

If we reboot the machine and read directly from /dev/video0 or
/dev/video1, we get perfect MPEG2 files.  However, once myth touches
it (either by recording or by way of “Live TV”), we get broken files,
both through myth and by reading directly off the card.

Our setup had been working fine until we started experimenting with the capture
resolution for the cards.  Initially, we had it set to 480x368, but
then changed it to 480x352 and 544x480 for unrelated reasons.  Setting
the capture resolution back to 480x368 does not solve the problem, nor
does upping the card resolution all the way up to 720x480.

We’ve tried a newer kernel (2.6.18->2.6.21) and the newest ivtv
drivers to no avail.

Does anyone have any idea how we may track down this problem?

Thanks!
	—Justin


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