Hi Hans,

there is still a problem since the early days of the ivtv driver:
Sometimes, immidiately after switching to a new (analogue) channel, the
picture begins to flicker. I analysed the stream and found out that in a GOP
of 12 pictures it is always the 4th and 10th picture which is faulty (see
pictures:
http://drseltsam.device.name/vdr/sample1.jpg
http://drseltsam.device.name/vdr/sample2.jpg )

In earlier ivtv-versions, it helped to switch the channel and go back. I
think it was starting with Rev 3349 when this didn`t help anymore. Since
this time I must stop the application and reload the ivtv-driver.

A reliable fix for the vdr-plugin "pvrinput" to avoid the flickering is to
close and open the device before setting a new channel:

close(video_fd);
char devName[64];
sprintf(devName, "/dev/video%d", number);
video_fd = open(devName, O_RDWR);

This makes channel switching 1-2 seconds slower, but the problem never
appeared again. Without this fix, I can reliably reproduce the problem.
Sometimes it takes a few dozen of channel switches, and sometimes it appars
after a few switches.

Do you have any idea how the problem could be fixed in a better way in the
driver?
The strange thing is that some vdr users know the flickering problem very
well while others never had problems. I don?t believe that it is a problem
of the application, because it happens with two totally different coded
plugins (analogtv and pvrinput).

Are there any similar reports from mythtv-users?

Greets,
Martin


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