[mythtv-users] Help with playback issue on recordings from a single channel

Hika van den Hoven hikavdh at gmail.com
Sat Dec 25 02:51:42 UTC 2021

Hoi Vincent,

Saturday, December 25, 2021, 2:25:59 AM, you wrote:

> I've been living with and frustrated by a problem with recordings
> from my local CBS broadcast channel.

> It all started when my local station added a new digital
> sub-channel.   I know this because my problem started on March 1st
> and a call to the station engineer confirmed changes were made to
> the broadcast signal early that Sunday morning. He says, "Everything
> in this encoding scheme is industry standard, so I wouldn’t expect
> there to be any problem decoding it with commercial equipment."  I'm
> not technical enough to determine what has changed that would give
> mythtv so much trouble.  Here are the symptoms:

> Prior to the change, I used VDPAU High Quality Video Playback
> Profile.   After the change, this profile on the bad channel will
> eventually cause my machine to lock up.  It starts with some serious
> macro blocking and then eventually freezes the display and I have to
> use power reset to recover my machine.   I discovered I am able to
> view the programs using Open GL High Quality.   I'm not happy about
> the higher CPU, but at least I can watch my programs.   However, two other bad symptoms manifest.

> After the change, the timing information of the recordings is off. 
> A 60 minute recording, when paused will report as 75 minutes.

> I suspect this is related to the third symptom which is that skip
> forward or back doesn't work properly.  The first skip forward will
> actually jump backward some random offset (usually 3 or 4 minutes)
> and then progress forward from there with repeated commands.   A
> skip backward does the same thing (first skip offset backwards 3 to 4 minutes).

> Note: I don't run any transcoding jobs on my recordings.   I've
> upgraded to Ubuntu 20.04.3 with latest mythtv patches
> (31.0+fixes.202111081900.25f1bb1d12~ubuntu20.04.1).

> Any suggestions?

To fix the skipping and the recordinglength, try rebuilding the

 /usr/bin/mythcommflag --rebuild -f %FILE% -V %VERBOSELEVEL%

I created a small shell script I called: RebuildSeekTable.sh

  declare FileName=${1:-""}
  [ "$FileName" == "" ] && exit 0
  declare Vlevel=${2:-206158430210}
  /usr/bin/mythcommflag --rebuild -f $FileName -V $Vlevel
  exit $?

And then created a userjob containing:

  <path to the script>/RebuildSeekTable.sh %FILE% %VERBOSELEVEL%

This way I can either automatically or manually run this job on any
misbehaving recordings.

Tot mails,
  Hika                            mailto:hikavdh at gmail.com

"Zonder hoop kun je niet leven
Zonder leven is er geen hoop
Het eeuwige dilemma
Zeker als je hoop moet vernietigen om te kunnen overleven!"

De lerende Mens

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