[mythtv] Assistance debugging a DVB/PMT tuning problem

Tom Dexter digitalaudiorock at gmail.com
Wed Jan 23 20:06:29 UTC 2008


I'm getting OTA broadcasts using HD-5500 tuners.  A local PBS channel
near me appears to have made some sort of change to their broadcast
stream that's preventing mythtv from getting a PTM from it.  I've
deleted and rescanned the channel and that didn't help.  I actually
didn't expect it to, as I had already tried creating a channels.conf
file with dvbscan and the frequency and all serviceid data in the
database where correct to begin with.  Here's the pertinent part of
the channels.conf file:

WNJB-DT:183028615:8VSB:49:52:3
NJN-3:183028615:8VSB:81:84:5
NJN-4:183028615:8VSB:97:100:6

Those service ids (3, 5, 6) match what's in my channels table (even
after the rescan).  I can actually tune those with mplayer using that
channels.conf file.  I'm not sure, but I think the two fields above
before the programid actually identify the audio/video streams, which
would seem to indicate that dvbscan found a PMT(??).

Mythtv gets a lock on the channel but simply can't get a PMT.  On the
frontend I get (LA_VG).  Here's the "-v channel" verbose output I get
trying to tune the first channel (WNJB-DT 58.1) above:

2008-01-23 13:13:21.867 DVBChan(2): Opening DVB channel
2008-01-23 13:13:21.871 DVBChan(2): SetChannelByString(58.1):
2008-01-23 13:13:21.875 DVBChan(2) Warning: Symbol Rate setting (0) is
out of range (min/max:5056941/10762000)
2008-01-23 13:13:21.876 DVBChan(2): Frequency: 183000000 Modulation: QPSK
2008-01-23 13:13:21.877 DVBChan(2): Old Params: Frequency: 659000000
Modulation: QPSK
                        DVBChan(2): New Params: Frequency: 183000000
Modulation: QPSK
2008-01-23 13:13:21.877 DVBChan(2): Tune(): Tuning to 183000000Hz
2008-01-23 13:13:21.878 dvbchannel.cpp:wait_for_backend: Status:
2008-01-23 13:13:21.880 DVBChan(2): Tune(): Frequency tuning successful.
2008-01-23 13:13:21.880 DVBChan(2): SetChannelByString(58.1): Tuned to
frequency.
2008-01-23 13:13:21.925 Finished recording All My Children: channel 1071
2008-01-23 13:13:21.968 DVBChan(2): Opening DVB channel
2008-01-23 13:13:21.975 SM(2)::AddFlags: Seen() Match() Wait(Sig,SNR,BER,UB,)
2008-01-23 13:13:21.976 DVBSM(2)::constructor(): initial flags 0x7400000
2008-01-23 13:13:21.977 DTVSM(2)::SetChannel(58, 1):
2008-01-23 13:13:21.978 SM(2)::RemoveFlags: Seen(PAT,PMT,VCT,)
Match(PAT,PMT,VCT,) Wait()
2008-01-23 13:13:21.978 SM(2)::AddFlags: Seen() Match() Wait(PAT,VCT,)
2008-01-23 13:13:21.980 SM(2)::AddFlags: Seen() Match() Wait(MGT,)
2008-01-23 13:13:21.981 SM(2)::Start: begin
2008-01-23 13:13:21.987 DVBSM(2)::UpdateValues: Signal Locked
2008-01-23 13:13:21.987 SM(2)::Start: end
2008-01-23 13:13:21.992 DVBSM(2): RunTableMonitorTS(): begin (# of pids 2)
2008-01-23 13:13:21.995 DVBSM(2)::AddPIDFilter(0x0):
2008-01-23 13:13:21.992 DVBSM(2)::UpdateValues: Waiting for table
monitor to start
2008-01-23 13:13:21.999 DVBSM(2)::UpdateValues: Table monitor started
2008-01-23 13:13:21.998 DVBSM(2)::AddPIDFilter(0x1ffb):
0: start_time: 4897.733 duration: 3.631
1: start_time: 4897.701 duration: 3.620
2: start_time: 4897.714 duration: 3.617
stream: start_time: 54418.904 duration: 40.695 bitrate=12454 kb/s
2008-01-23 13:13:22.005 AFD: Opened codec 0x81cb730, id(MPEG2VIDEO) type(Video)
2008-01-23 13:13:22.009 AFD: Opened codec 0x8232570, id(AC3) type(Audio)
2008-01-23 13:13:22.012 AFD: Opened codec 0x822ac70, id(AC3) type(Audio)
2008-01-23 13:13:22.112 SM(2)::AddFlags: Seen(PAT,) Match() Wait()
[mpeg2video @ 0xb73e94a8]invalid cbp at 55 34
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 41 34
[mpeg2video @ 0xb73e94a8]invalid cbp at 28 35
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 65 35
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 4 36
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 11 37
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 62 38
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 9 38
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 21 39
[mpeg2video @ 0xb73e94a8]mb incr damaged
[mpeg2video @ 0xb73e94a8]slice mismatch
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 22 40
[mpeg2video @ 0xb73e94a8]slice mismatch
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 70 40
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 51 41
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 46 41
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 54 42
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 65 42
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 4 43
[mpeg2video @ 0xb73e94a8]ac-tex damaged at 22 44
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 15 44
[mpeg2video @ 0xb73e94a8]invalid mb type in P Frame at 41 44
2008-01-23 13:13:22.167 SM(2)::AddFlags: Seen(MGT,) Match() Wait()
2008-01-23 13:13:22.171 SM(2)::AddFlags: Seen() Match(MGT,) Wait()
2008-01-23 13:13:22.223 SM(2)::AddFlags: Seen(VCT,TVCT,) Match() Wait()
2008-01-23 13:13:22.224 DTVSM(2)::SetVCT(): tvct->ProgramNumber(idx
0): prog num 3
2008-01-23 13:13:22.225 DTVSM(2)::SetProgramNumber(3):
2008-01-23 13:13:22.225 SM(2)::RemoveFlags: Seen(PMT,) Match(PMT,) Wait()
2008-01-23 13:13:22.226 SM(2)::AddFlags: Seen(PAT,) Match() Wait()
2008-01-23 13:13:22.226 SM(2)::AddFlags: Seen() Match(PAT,) Wait()
2008-01-23 13:13:22.227 SM(2)::AddFlags: Seen() Match() Wait(PMT,)
2008-01-23 13:13:22.227 SM(2)::AddFlags: Seen() Match(VCT,TVCT,) Wait()
2008-01-23 13:13:22.228 DVBSM(2)::AddPIDFilter(0x30):
2008-01-23 13:13:22.279 DTVSM(2)::GetStatusList: WaitForPMT seen(0) matching(0)

That's as far as it gets, and the recorder creates a zero length file.
 By the way, I can also tune those with an old Samsung receiver I
have.

 Any idea what might cause that?  Thanks for any suggestions!

Tom


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