[MPlayer-dev-eng] Proposed patch: ignore bad consistency counter check in demux_ts

[Nico Sabbi]

Il giorno sab, 21/02/2009 alle 02.55 -0800, Trent Piepho ha scritto:
> On Fri, 20 Feb 2009, Nico Sabbi wrote:
> > On Thursday 19 February 2009 23:21:49 Steven Brudenell wrote:
> > > Turning up verbosity revealed messages like "GOOD CC: 3, BAD CC:
> > > 29" shortly before exiting. It seems that demux_ts checks the
> > > "continuity counter" bit of mpeg streams before deciding that it is
> > > indeed a TS. Apparently these continuity counters don't come across
> > > well in high-bitrate DVB streams for some reason.
> > >
> > > I noticed that CCs aren't verified during stream playback (the code
> > > to do this seems commented out, so I guess they were at some
> > > point), so I guess this must not be that critical to stream
> > > playback.
> > >
> >
> > that check is only necessary during the demux_open() phase, that is
> > when a stream is analyzed to guess the format of the multiplex.
> > Disabling that check would make a lot of garbage appear like MPEG-TS,
> > that is obviouly unacceptable.
> >
> > Your problem lies somewhere else: in your reception conditions.
> > Passing an option to the demuxer is as easy as adding the variable on
> > top of the file and modifying cfg-common.h accordingly. Look at
> > ts_probe as an example
> 
> Sometimes demodulators take a couple seconds to lock to the stream.  Before
> that the error rate is a lot higher.  Since the demuxer is only going to
> check the beginning of the data, it may be getting too much bad data to
> recognize the stream as TS even though the stream would still be playable
> after a few seconds.  A high bit rate stream will fill up the demuxer's
> probe buffer much faster and thus get more bad data while the demodulator
> is still locking.
> 
> If the input is DVB, then the probability of the stream being TS is nearly
> 100%.  Certainly the autodetection logic could take that into account.


stream_dvb already sets DEMUXER_TYPE_MPEGTS to the stream_type to check
that format first. Raising the check buffer is another option to
consider