[linux-dvb] Re: A/V disturbances while recording (was:Today's CVS driver)

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

Klaus Schmidinger writes:
 > I just made the following experiment:
 > 
 > My third DVB card recorded the current ZDF programme, while the first card
 > immediately replayed the recorded data. My tv set is able to do PIP
 > (picture in picture), so I was able to view the live signal from the AV output
 > of the third card as well as the replayed signal from the first card (with a few
 > seconds delay).
 > 
 > Much to my surprise the audio disturbances and video artifacts happened on the
 > *LIVE* signal - the recording just repeated what it had received earlier.
 > 
 > Another test with 3sat showed the same errors in the *LIVE* signal.
 > 
 > I then recorded 3sat with my third card and also tuned to 3sat on my first
 > card, thus having the live picture on both a card that is currently recording
 > and one that is just showing the programme. As I already expected, the disturbances
 > happened only on the card that was recording.
 > 
 > I double checked this with the CVS driver version 2001-05-17, where during several
 > minutes of testing I have observed only one such disturbance. So it would appear that
 > this has become a lot worse between CVS driver versions 2001-05-17 and 2001-05-25.
 > 
 > Whether or not such disturbances happen apparently depends on what kind of
 > programme is currently broadcast. There are times when (even with the latest driver)
 > I can't observe any errors for several minutes, and other times when they occur every
 > few seconds. It would appear that 3sat is a good test candidate, and here especially
 > the "nano" programme. But also the ZDF shows this behaviour.
 > 
 > Can anybody else reproduce these effects?
 > 
 > Can the driver developers think of anything that might cause this?
 > I don't think that the *live* signal should be affected by the fact that
 > the card is recording!?
 > 
 > Am I doing something wrong here?
 > 

My guess would be that it has something to do with OSD since that is
the only thing we are not really using. We had no problems here.

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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