[mythtv-users] DVB-C: Problems with just couple of multiplexes

Kari Salmela kari.salmela at lanwan.fi
Mon Aug 21 06:01:28 UTC 2006


I am experiencing some severe picture quality problems (errors at rate
sometimes >10/second) with certain channels with svn 10856 (and earlier
Most of the channels work ok though. It would be easy to think it's a
signal quality problem, but when I czap to one of the problematic
channels, BER is 0 all the time and signal is at same level than the
channels which work ok. These are encrypted channels, so I moved CAM to
another card just to exclude bad card. CPU load is ~20% when watching
live tv and ~1% when only recording, so it should not be a performance
problem either. (how one could tell whether system really is performing
too slow??) Sometimes cpu load is >1, but other channels work just fine.

The picture has dropouts, sound has clicks and bleeps and I get errors
in console look like this:
[mpeg2video @ 0xb74247e4]*ac*-*tex* damaged at 0 14
[mpeg2video @ 0xb74247e4]skipped MB in I frame at 2 20
[mpeg2video @ 0xb74247e4]invalid mb type in I Frame at 0 14

I have two Technotrend DVB-C 1500 cards. The channels which do not work
ok are defined like this in channels.conf:
CANAL+ FILM:266000000:INVERSION_AUTO:6900000:FEC_NONE:QAM_128:512:650:301
CANAL+ FILM2:266000000:INVERSION_AUTO:6900000:FEC_NONE:QAM_128:515:682:308
CANAL+ SPORT:266000000:INVERSION_AUTO:6900000:FEC_NONE:QAM_128:514:670:305
C MORE FILM:266000000:INVERSION_AUTO:6900000:FEC_NONE:QAM_128:519:689:313

however fairly similar channels do work ok.. (has encryption, has QAM128

Sky News:138000000:INVERSION_AUTO:6900000:FEC_NONE:QAM_128:515:652:1013
Bloomberg English

266Mhz is the same frequency my motherboard fsb runs (Asus A7V266-EX)  ;-)

Any ideas how to debug this?


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