[mythtv-users] Weird playback problem on some channels

Curtis Stanford curtis at stanfordcomputing.com
Sat Sep 1 19:19:16 UTC 2007

OK, I'm going to give this another try since it's bugging me so much.

I've put up a 250M portion of an mpeg file at http:// 
stanfordcomputing.com/bad.mpg. It comes from one of about 5 channels  
I have that produce these types of files that don't play correctly in  
myth. It is coming from a firewire connection. Of course, the cable  
box itself has no problem with these mpeg streams. Also, mplayer  
plays them OK too, except it can't find the codec for the audio so I  
get no sound (setup problem perhaps). In myth, I've tried all  
combinations of syncing, interlacing, audio, etc. to no avail. Here's  
what happens when I play these files in myth:

- If I just start it playing and leave it, it plays fine  
(occasionally audio is a little out of sync)

- If I pause and restart, it's fine.

- If I speed it up or slow it down (using J/U keys), it's fine.

- However, if I jump at all using the arrow keys, it starts playing  
in super-fast motion. Bookmarking and resuming has the same problem.  
At first sound is normal but video is fast. After a few seconds, the  
audio speeds up as well and becomes unwatchable. Nothing I do after  
this can restore it to normal. I have to start at the beginning again.

I suspect the cable box plays them correctly because there is never  
any jumping around. This is something that has changed in the last  
few months. Either the stream has changed or myth has. I've been  
keeping up with the SVN versions and they all have the same problem  
in the last few months.

My hope is that someone who knows a lot more about mpeg2 streams than  
me can take a look at this. I don't know if there is anyone else  
using firewire in Calgary on Shaw Cable but I'd be interested to know  
if they are having the same problems on the Movie Central channels  
(55, 56, 57).



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