[linux-dvb] Re: Continuity Errors with tda10021 (Re: Distorded video with Cinergy1200 DVB-C)

slickhenry slickh at gmail.com
Wed Feb 16 16:32:48 CET 2005


Robert Schlabbach:
> Is it possible that the "distortions" you are seeing are _not_ the result
> of reception errors, but rather the result of incorrect DMA transfers from
> the SAA7146A to the PCI bus? If you have no issues with QAM64 channels,
> that might only be due to their lower data rate.

All my channels are QAM64.

> You should make sure the register bit which makes the TDA10021 set the TEI
> bit in any packets incorrectly received, and then dump and examine the raw
> MPEG-2 transport from from an QAM128 channel. If you have TEI errors and
> continuity errors in there, it's a reception problem. However, if you
> _only_ have continuity counter errors in there, it's a DMA error.

I've gotten around to play with dvbsnoop. And indeed,
Transport_error_indicator remains 0 all the time, while the continuity
counters seem to indicate lots of lost ts-packets for the garbled channels.

Is there any way of rectifying this or reasearch where they are lost?

For a bad channel:
$ grep continuity_counter bad-a.snoop | head -10
continuity_counter: 5 (0x05)
continuity_counter: 6 (0x06)
continuity_counter: 9 (0x09)
continuity_counter: 12 (0x0c)
continuity_counter: 13 (0x0d)
continuity_counter: 14 (0x0e)
continuity_counter: 12 (0x0c)
continuity_counter: 1 (0x01)
continuity_counter: 2 (0x02)
continuity_counter: 3 (0x03)

For a good channel:
$ grep continuity_counter good-a.snoop | head -10
continuity_counter: 14 (0x0e)
continuity_counter: 15 (0x0f)
continuity_counter: 0 (0x00)
continuity_counter: 1 (0x01)
continuity_counter: 2 (0x02)
continuity_counter: 3 (0x03)
continuity_counter: 5 (0x05)
continuity_counter: 4 (0x04)
continuity_counter: 5 (0x05)
continuity_counter: 6 (0x06)






More information about the linux-dvb mailing list