Occasional zero length mythtv recordings

[puterguy]

I am using the latest mythtv 0.20.2-169 packages with a pchdtv 5500 (and also an older winfast 2000xp).

I notice that occasionally I get zero length recordings - i.e. the show itself shows up in mythfrontend with the appropriate timeslot and description but the recording itself is an empty file.

It probably happens about 5% of the time but I have not noticed a definite pattern though it tends to happen more to some shows/channels than others. Note that I am using the OTA us-broadcast ATSC signals from the dvb tuner on the pchdtv5500 card. All signals are >70% strength since I am only a couple of miles from (and in sight line of) the antennas.

I don't see any log entries in /var/log/mythtv/mythbackend.log (or even in /var/log/messages)

mentioning problems.

The only relevant entries I have are:

    2007-12-23 05:30:02.589 TVRec(1): Changing from None to RecordingOnly
    2007-12-23 05:30:02.618 TVRec(1): HW Tuner: 1->1
    2007-12-23 05:30:02.646 DVBChan(0) Warning: Symbol Rate setting (0) is out of range (min/max:5056941/10762000)
    2007-12-23 05:30:02.664 Started recording: Hometime "Fold-Down Bed": channel 2041 on cardid 1, sourceid 2
    2007-12-23 06:00:00.983 TVRec(1): Changing from RecordingOnly to None
    2007-12-23 06:00:01.464 Finished recording Hometime "Fold-Down Bed": channel 2041
    2007-12-23 06:00:01.486 Reschedule requested for id 0.
    2007-12-23 06:00:02.011 Scheduled 93 items in 0.5 = 0.03 match + 0.50 place

The only log difference I see between this failed recording and all the other successful recordings is that during a successful recording, I get a SECOND "Finished recording..." line between the "Reschedule requested for id 0" line and the "Scheduled X items..." line. Also, in a successful recording, I get a series of lines following the "Scehduled XX items..." line that seem to describe the recorded stream that don't appear in the corresponding failed recording

Here is an example of a SUCCESSFUL recording of the same show:

     2007-12-16 05:30:02.624 TVRec(1): Changing from None to RecordingOnly
     2007-12-16 05:30:02.650 TVRec(1): HW Tuner: 1->1
     2007-12-16 05:30:02.683 DVBChan(0) Warning: Symbol Rate setting (0) is out of range (min/max:5056941/10762000)
     2007-12-16 05:30:02.731 Started recording: Hometime "Pint-Sized Fireplace": channel 2041 on cardid 1, sourceid 2
     2007-12-16 06:00:00.170 TVRec(1): Changing from RecordingOnly to None
     2007-12-16 06:00:00.253 Finished recording Hometime "Pint-Sized Fireplace": channel 2041
     2007-12-16 06:00:00.293 Reschedule requested for id 0.
     2007-12-16 06:00:01.049 Finished recording Hometime "Pint-Sized Fireplace": channel 2041
     2007-12-16 06:00:01.109 Scheduled 87 items in 0.8 = 0.00 match + 0.81 place
     0: start_time: 8230.118 duration: 161.642
     1: start_time: 8230.086 duration: 161.637
     stream: start_time: 91445.405 duration: 1796.378 bitrate=18504 kb/s
     2007-12-16 06:00:01.211 AFD: Opened codec 0xae1d2d20, id(MPEG2VIDEO) type(Video)
     2007-12-16 06:00:01.241 AFD: Opened codec 0xae1d3320, id(AC3) type(Audio)
     [mpeg2video @ 0x35782c0]ac-tex damaged at 10 67
     [mpeg2video @ 0x35782c0]00 motion_type at 57 67
     [mpeg2video @ 0x35782c0]00 motion_type at 83 67
     CC length(103) seq_num(1) 0x74 0x61
     CC length(103) seq_num(1) 0x74 0x61
     CC length(103) seq_num(1) 0x74 0x61

Note that I get the DVBChan(0) Warning even when recording works (and also whenever I start mythbackend). I'm not sure what it means (does anybody?) but it doesn't seem like the problem here.

So in summary:

1. What is causing these zero length recordings?
   
2. How do I fix the problem?
   
3. Shouldn't mythtv give better error messaging when zero length recordings occur?
   
4. Shouldn't mythtv fail more gracefully in terms of:
   
   • Deleting the zero length recording from the recorded programs menu
     
   • Making sure that the show is not marked as recorded
     
   • Reschedule showing for another time if there is another slot for the same show in the future
     

[Janne Grunau]

please redo the backend logs with -v record,channel,siparser

[xris]

See #3872 and #3995, too.

[stuartm]

Requested logs not provided after 2 months.

[Petr Stehlik <pstehlik@…>]

I have a different setup (DVB-S SkyStar2) but I have been getting the empty recordings as well for couple of months already so I thought I'd hijack/reopen this ticket and attach my log. For comparison with the attached failed.log.gz there is a working.log.gz (too large so not attached): ​http://joy.sophics.cz/tmp/working.log.gz showing recording of the same program at different time of the same day.

I find interesting that the failed.log.gz contains "Deleting stale pending recording" (three times) but the working.log.gz contains the same message as well (three times, too :-) The difference is that the failed recording cannot be replayed (it doesn't even exist as a file on the disk).

[Petr Stehlik <pstehlik@…>]

shows failed recording that looks like empty recording in the frontend

[stuartm]

Duplicate of #3872.

There is no bug in the logs from Petr, it was unable to record because the channel was encrypted. Chances are, that like channels on DVB-S here in the UK, the channel is encrypted in the evenings and FTA during the day.