[mythtv] Too much EIT activity causing defective recordings

Michael T. Dean mtdean at thirdcontact.com
Wed Aug 1 11:49:05 UTC 2018


On 07/31/2018 06:51 PM, John Pilkington wrote:
> Hi;  I'm running Master under SL7, recording UK SD DVB-T material via 
> one PCI single-tuner device and one twin-tuner usb dongle.
>
> Bus 001 Device 002: ID 1b80:e409 Afatech IT9137FN Dual DVB-T [KWorld 
> UB499-2T]
>
> Around 9 July my Project-X-based mythDVBcut logs started reporting 
> multiple AV sync corrections of up to a second in recordings from the 
> usb tuners.  The change occurred after I rescanned my transports 
> following the Wimbledon special tennis coverage;  I'm fairly sure I 
> made other 'minor' changes in the multirec and EIT configs too.
>
> Today I realised that the defects were often around 5 minutes apart, 
> and EIT scanning seemed a possible culprit.  I have now unchecked the 
> boxes for usb open-on-demand and active-EIT-scan, and it looks as if 
> the recording defects have largely gone.
>
> In the past I probably haven't taken as much notice of the EIT 
> settings as I should have done, but the recent defects were much worse 
> than I had seen before and I think some of the recent code changes 
> must have been implicated.
>
> John P
>
> Below is a Project-X log resync section from an affected recording. 
> This should be just a few lines, with no resync required.
>
> {{{
>
> Input File 0:  '/mnt/dat2/RSG3/1004_20180723195800.ts.old' 
> (1,149,983,780 bytes)
> -> Filetype is TS (generic PES Container)
>
> <demux log snipped>
>
> ++> Mpg Audio: PID 0x044E / PesID 0xC0 / SubID 0x00 :
> -> check CRC of AC-3 / MPEG-Audio L1,2
> -> remove CRC in MPEG-Audio L1,2
> -> add frames
> -> Audio PTS: first packet 08:48:35.071, last packet 09:48:52.207
> -> Video PTS: start 1.GOP 08:48:41.439, end last GOP 09:48:41.999
> -> adjusting audio at video-timeline
> -> src_audio: MPEG-1, Layer2, 48000Hz, stereo, 192kbps, noCRC @ 
> 00:00:00.000
> !> 5 frame(s) (120ms) inserted @ 00:02:28.608
> !> missing syncword @  6527233, @ 00:04:08.064
> !> found syncword @ 6528384
> !> 22 frame(s) (528ms) inserted @ 00:04:08.064
> !> missing syncword @  6528961, @ 00:04:08.592
> !> found syncword @ 6529352
> !> missing syncword @  14213193, @ 00:09:27.840
> !> found syncword @ 14213560
> !> missing syncword @  14214137, @ 00:09:27.864
> !> found syncword @ 14214344
> !> 4 frame(s) (96ms) inserted @ 00:09:27.864
> !> missing syncword @  29606793, @ 00:16:02.448
> !> found syncword @ 29607000
> !> 1 frame(s) (24ms) inserted @ 00:16:02.448
> !> 19 frame(s) (456ms) inserted @ 00:21:21.144
> !> missing syncword @  45001753, @ 00:26:40.656
> !> found syncword @ 45001960
> !> 23 frame(s) (552ms) inserted @ 00:26:40.680
> !> missing syncword @  52701353, @ 00:27:54.144
> !> found syncword @ 52701536
> !> missing syncword @  52702689, @ 00:27:54.192
> !> found syncword @ 52703080
> !> 20 frame(s) (480ms) inserted @ 00:27:54.192
> !> missing syncword @  60403625, @ 00:33:14.592
> !> found syncword @ 60404248
> !> 17 frame(s) (408ms) inserted @ 00:33:14.616
> !> missing syncword @  68103065, @ 00:38:34.344
> !> found syncword @ 68103712
> !> 17 frame(s) (408ms) inserted @ 00:38:34.344
> !> missing syncword @  68120993, @ 00:38:34.752
> !> found syncword @ 68121960
> !> 2 frame(s) (48ms) inserted @ 00:38:34.752
> !> missing syncword @  75797161, @ 00:39:47.760
> !> found syncword @ 75797944
> !> missing syncword @  83496185, @ 00:45:07.344
> !> found syncword @ 83496968
> !> 21 frame(s) (504ms) inserted @ 00:45:07.416
> !> missing syncword @  83504457, @ 00:45:07.920
> !> found syncword @ 83505080
> !> missing syncword @  83566137, @ 00:45:09.816
> !> found syncword @ 83566920
> !> 2 frame(s) (48ms) inserted @ 00:45:09.816
> !> 2 frame(s) (48ms) inserted @ 00:45:09.960
> audio frames: wri-pre-skip-ins-add 117813-0-0-155-0 @ 00:47:07.512 
> done...
> ---> new File: '/home/john/MythTmp/tempcut19417.mp2'
>
> summary of created media files:
> .Video (m2v):    70688 Frames    00:47:07.520 
> '/home/john/MythTmp/tempcut19417.m2v'
> Audio 00 (mp2):    117813 Frames    00:47:07.512    0-0-155-0 
> '/home/john/MythTmp/tempcut19417.mp2'
> => 775,195,585 bytes written...
> -> we have 139 warnings/errors.
>
> }}}

Could this be due to I/O activity? Have you done an optimize on your 
database, recently?  If not, it may just be that MySQL is taking too 
much time with I/O when MythTV tries to write your listings data and it 
causes problems with MythTV's writing recording data.  Do you have any 
warnings or errors in your MythTV backend logs?

Mike


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