DVB-C recording bug (was: Re: [mythtv] Having some problems with DVB-C and mythTV 0.11)

[Georg C. F. Greve]

Hi all,

although DVB in general seems to be working, there is a strange
problem with recording. 

When using femon to monitor the status of the DVB-C card, I get
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[...]
status 00 | signal 8080 | snr 0000 | ber 00000190 | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 00000190 | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 00000190 | unc 00000000 | 
status 00 | signal 2525 | snr a8a8 | ber 00000190 | unc ffffffff | 
status 1f | signal ffff | snr e9e9 | ber 00000190 | unc ffffffff | FE_HAS_LOCK
status 1f | signal ffff | snr eaea | ber 00000190 | unc 00000000 | FE_HAS_LOCK
status 1f | signal ffff | snr e9e9 | ber 0005af14 | unc 00000000 | FE_HAS_LOCK
status 1f | signal ffff | snr e4e4 | ber 0005af14 | unc 00000000 | FE_HAS_LOCK
status 1f | signal ffff | snr e9e9 | ber 0005af14 | unc 00000000 | FE_HAS_LOCK
status 00 | signal 8080 | snr 0000 | ber 000000fa | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 000000fa | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 000000fa | unc 00000000 | 
[...]
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at startup of mythtv and its log shows
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Starting up as the master server.
Probed: /dev/video - Television
Probed: /dev/video - Composite1
Probed: /dev/video - S-Video
Probed: /dev/video - Composite3
DVBChannel: Changing to channel 54 on card 0
Using DVB card "VES1820 based DVB-C frontend"
tuning DVB-C to 394000000, srate=6900000
polling....
Getting frontend event
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI FE_HAS_SYNC
Bit error rate: 400
Signal strength: 56026
SNR: 59624
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI FE_HAS_SYNC
SetPID:  310 320
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So everything looks as it should, I'd say.

If I now schedule a recording from the DVB card, I get the following
information (having selected verbose) in the mythTV log
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2003-08-18 18:02:56 Started recording "Denk bloß nicht, ich heule" on channel: 1046 on cardid: 2, sourceid 2
DVBChannel: Changing to channel 46 on card 0
Using DVB card "VES1820 based DVB-C frontend"
tuning DVB-C to 426000000, srate=6900000
polling....
Getting frontend event
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI FE_HAS_SYNC
Bit error rate: 250
Signal strength: 56026
SNR: 59110
FE_STATUS: FE_HAS_SIGNAL FE_HAS_LOCK FE_HAS_CARRIER FE_HAS_VITERBI FE_HAS_SYNC
SetPID:  301 302
DVBChannel: Closed DVB demux devices!
Changing from None to RecordingOnly
filtering pids: 301 302
Audiostream: Layer: 2  BRate: 192 kb/s  Freq: 48.0 kHz
Videostream: ASPECT: 4:3  Size = 720x576  FRate: 25 fps  BRate: 7.00 Mbit/s
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and femon shows me
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[...]
status 00 | signal 8080 | snr 0000 | ber 000000fa | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 000000fa | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 000000fa | unc 00000000 | 
status 00 | signal 8080 | snr b5b5 | ber 000000fa | unc ffffffff | 
status 1f | signal ffff | snr e6e6 | ber 000000fa | unc ffffffff | FE_HAS_LOCK
status 1f | signal ffff | snr e7e7 | ber 000000fa | unc 00000000 | FE_HAS_LOCK
status 1f | signal ffff | snr e6e6 | ber 0006ae96 | unc 00000000 | FE_HAS_LOCK
status 1f | signal ffff | snr e5e5 | ber 0006ae96 | unc 00000000 | FE_HAS_LOCK
status 1f | signal ffff | snr e6e6 | ber 00000622 | unc 00000000 | FE_HAS_LOCK
status 00 | signal 8080 | snr 0000 | ber 00000622 | unc 00000000 | 
status 00 | signal 8080 | snr 0000 | ber 00000622 | unc 00000000 | 
[...]
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There is a recording in the list of recordings, but it is only a few
seconds, not the whole show.

All of this seems to hint at a bug in DVB-C recording, in fact I'd say
that the error possibly is for mythTV to not keep that channel open,
so after selecting a channel, the signal is quickly lost.

Maybe the routine is closing the device after selecting a channel? It
seems that it shouldn't do that.

Regards,
Georg

-- 
Georg C. F. Greve                                       <greve at gnu.org>
Free Software Foundation Europe	                 (http://fsfeurope.org)
Brave GNU World	                           (http://brave-gnu-world.org)