[mythtv-users] DVB-C and hangs when changing channels

[Tuomas Jormola]

Hello,

I live in a dorm with small cable network covering the campus area. I'm using
MythTV from current CVS and Technotrend DVB-C 2.1 card with stock kernel 2.6.5
drivers. I don't know if it's the network or my system but sometimes changing
channels fails. The backend just hangs with these log entries (running
mythbackend -v all).

2004-04-26 20:40:26 DVB#0 Trying to tune to channel 14.
2004-04-26 20:40:26 DVB#0 Frequency: 290000000 Symbol Rate: 7146000. Inv:Auto Fec:None Mod:64
2004-04-26 20:40:27 DVB#0 Waiting for frontend event after tune.
2004-04-26 20:40:27 DVB#0 WARNING - Status: NO LOCK!
2004-04-26 20:40:27 DVB#0 Status: CARRIER | VITERBI | SIGNAL | SYNC | LOCK.
2004-04-26 20:40:27 DVB#0 Successfully tuned to channel 14.
2004-04-26 20:40:27 2       ok
2004-04-26 20:40:27 DVB#0 Adding pid 644, type 0
2004-04-26 20:40:27 DVB#0 Adding pid 513, type 1
2004-04-26 20:40:27 16      1[]:[]1021313024
2004-04-26 20:40:27 121     World Business Report[]:[] []:[] []:[] []:[]200...
2004-04-26 20:40:27 7       0[]:[]0
2004-04-26 20:40:27 DVB#0 Adding pid 1001, type 2
2004-04-26 20:40:28 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:28 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:29 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:29 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:29 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:30 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:31 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:31 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:32 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:32 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:32 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:33 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:34 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:34 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:34 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:35 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:36 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:36 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:36 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:37 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:37 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:38 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:38 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:39 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:40 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:41 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:41 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:41 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:42 Couldn't read data from the capture card in 15 seconds.  Game over, man.
2004-04-26 20:40:42 1       0
2004-04-26 20:40:42 1       0
2004-04-26 20:40:42 1       0
2004-04-26 20:40:42 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:42 1       0
2004-04-26 20:40:42 1       0
2004-04-26 20:40:42 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:43 1       0
2004-04-26 20:40:43 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:43 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:43 1       0
2004-04-26 20:40:43 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:43 1       0
2004-04-26 20:40:43 1       0
2004-04-26 20:40:43 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:43 1       0
2004-04-26 20:40:44 1       0
2004-04-26 20:40:44 1       0
2004-04-26 20:40:44 1       0
2004-04-26 20:40:44 1       0
2004-04-26 20:40:44 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:44 1       0
2004-04-26 20:40:45 1       0
2004-04-26 20:40:45 1       0
2004-04-26 20:40:45 1       0
2004-04-26 20:40:45 1       0
2004-04-26 20:40:45 DVB#0 WARNING - No data from card in 1 second.
2004-04-26 20:40:45 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:45 1       0
2004-04-26 20:40:46 DVB#0 WARNING - Uncorrectable error in packet, dropped.
2004-04-26 20:40:46 1       0
2004-04-26 20:40:46 DVB#0 WARNING - Uncorrectable error in packet, dropped.

This happens with about 5-10% of channel changes. It just repeats the last log
entries forever so it requires restarting both backend and frontend in order to
recover, which is pretty irritating in the long run. It happens with all
channels that are available in the network. But when a stream is flowing, it's
never interrupted and picture is great etc. so it's stable when you get it
running. Problem only exists immediatelly after a channel change. Any ideas
what could be wrong? Or any hints if there're some timing settings or something
that I might try to tune in the source code and check if it helps (I'm not
afraid to hack and debug things, it's just that I don't have any previous
experience with MythTV codebase and DVB(-C) technology :)

Thanks,

-- 
Tuomas Jormola <tjormola at cc.hut.fi>