[linux-dvb] Re: mplex loses sound

[Marcus O.C. Metzler <mocm@convergence.de>]

Klaus Schmidinger writes:
 > "Marcus O.C. Metzler" wrote:
 > > 
 > > Klaus Schmidinger writes:
 > >  > I just tried to remux a recording I made a few days ago
 > >  > (and which had some audio glitches). So I did
 > >  >
 > >  >   mplex -t MPEG2 -o 001.vdr 001.vdr.x
 > >  >
 > >  > where '001.vdr.x' was my original recording. The resulting
 > >  > file started to replay just fine, but after about one minute
 > >  > the audio suddenly disappeared and never came back, even if I
 > >  > fast-forwarded all the way through the recording.
 > >  >
 > >  > The same thing happens if I replay the recording with 'cat',
 > >  > which rules out a problem in VDR.
 > >  >
 > >  > Could this be a bug in 'mplex'?
 > >  >
 > >  > Klaus
 > > If the input file has a real audio glitch, i.e. an error that comes
 > > from bad reception, mplex cannot multiplex the streams.
 > 
 > 
 > Here's what I get from es_demux:
 > 
 > kls@video:/video/nano/2001-02-27.18:28.10.05.rec > ~/vdr/DVB/apps/mpegtools/es_demux 001.vdr.x x.x x.y
 > Reading 001.vdr.x
 > Opening x.x for audio
 > Opening x.y for video
 > VPTS - APTS = 0.2854s
 > 
 > I don't know if this was a stupid thing to do, but when I did
 > 
 >   cat x.x > /dev/video0

That wont work, because you can't play back ES streams on that device.

 > 
 > (where x.x was the file from the es_demux call) the TV screen went black (no
 > sound) and my machine totally locked up (interestingly it could still be ping'ed
 > from another computer, but that's all). I had to do a reset to get it up and
 > running again. Maybe the driver locks up when it receives certain unsuitable
 > data? Well, whatever one sends to the driver, it should never lock up the
 > entire system.

It tries to find a suitable header and has to go through the file byte
by byte. That hangs the system.

 > 
 > If you'd like to take a look at the audio file produced by es_demux, I could
 > make it available on our server. It is about 23 MB in size, but I guess the problematic
 > area should be within the first few MBs, so I guess it would suffice if I
 > upload, say, 2MB. Please let me know.
 > 

Just do mpg123 <filename> that should tell you if its broken.

Marcus

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Dr. Marcus Metzler                             
mocm@netcologne.de                     http://www.metzlerbros.de
mocm@convergence.de                    http://www.convergence.de

Convergence Integrated Media GmbH          
Rosenthaler Str. 51                   
D-10178 Berlin                             
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