[mythtv] possible libavformat incompatibility with certain MPEG TS files

Daniel Kristjansson danielk at cuymedia.net
Fri May 26 13:58:56 UTC 2006

On Fri, 2006-05-26 at 09:55 +0100, Rob Jones wrote:
> Hi,
> I've been attempting to setup a dbox2 with mythtv (0.19 fixes branch).
> Streaming of transport streams from the dbox  works ok, but libavformat
> has issues reading the tables and assigning the PIDs when attempting to
> play back the stream in myth. It doesn't *seem* to be a problem with
> anything non-standard in the file, as dvbsnoop, tsreader analyzers have
> no problems showing its contents, with a PMT and video/audio PIDs, and
> mplayer etc. have no problems playing it back.

This is probably because the (lack of) PMT handling in the
dbox2recorder. If you want to fix it, look at something like
DVBRecorder or HDHRRecorder. DVBRecorder listens to the
HandlePAT/HandlePMT signals from the stream data class and
creates the output tables itself, the HDHRRecorder listens
to HandleSingleProgramPAT/HandleSingleProgramPMT which gives
it generically cleaned up tables from the stream data class.
Either approach will probably fix your problem.

mplayer doesn't track PMT changes in the stream, so it won't
pick up new streams such as dvb subtitles, audio, or new video
streams, and it will get stuck when a stream goes away. But
since it just ignores the PMT's after the first one, this also
means it won't get thrown off by PMT trashing like this.

If you're fixing this it would be nice if you also implemented
a DBOX2SignalMonitor class. Tracking the PAT/PMT tables for
the DBOX2 in the signal monitor would mean MythTV wouldn't get
thrown of when the available DBOX2 channels change, or the DBOX2
hardware is turned off.

-- Daniel

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