[mythtv-users] 0.27.1 stores wrong length in SD mpeg2 recordings

Stephen Worthington stephen_agent at jsw.gen.nz
Sat Jun 21 10:48:05 UTC 2014


On Sat, 21 Jun 2014 01:41:23 +0200, you wrote:

>Hoi Discussion,
>
>About a month ago a moved from 0.26 to 0.27 and then 0.27.1.
>Since then I have a problem with my recordings. I only record SD with
>a PVR350 and a PVR500, so hardware mpeg2 recorders.
>Here some statistics from first 0.26
>recorded from till shown length on playback
>     18:35-20:20   1:44:59
>     20:05-21:50   1:44:57
>     18:35-20:20   1:44:59
>and recent recordings
>     19:00-20:45   1:31:32
>     18:00-18:31   0:27:07
>      9:04-10:15   1:04:03
>As you see the shown length is 10 to 13% to short and also has nothing
>to do with the show length, which often is about that much shorter,
>but not for the fifth recording. (30 min)
>
>I first noticed it because if I jumped back a little (I have left set
>to jump back 10s and right to forward 1 min) I jumped forward one to
>several minutes. Depending on how far I was in the recording and the
>time since the last jump. If the recording comes at the end of the
>shown length it plays on till the real end.
>Also commercial flagging is screwed up by this.
>If I transcode either inside to nuv or outside by way of dv back to
>mpeg2 (I use kino to remove commercials. The resulting mpeg2 file is
>half the size without noticeable quality loss) the problem is gone.
>
>The problem exists only with recordings under 0.27/0.27.1.

I had problems with skipping like that (in 0.26?), but the opposite
way around, with my older PVR-500 recordings.  As best I can recall,
the skipping worked much as you are describing.  I am not sure what
version it started with, but what I had to do was make myself a User
Job ("Rebuild seek table"):

  mythcommflag --rebuild -f %FILE%

If I run that on an old recording, then the skipping works properly
again.  I never did any research on it, but I just assumed that how
the seek table data worked had been changed in the new version and it
needed to be re-created.  Fortunately, my new MythTV box is quite fast
and I can run that job on an old file in less than a minute.

I have no idea how PVR-500 recordings work in 0.27 as I do not use my
PVR-500 any more. I am now recording digitally from the channels I
used to use the S-Video output from my STB for.  I can not remember
for sure if new PVR-500 recordings worked OK or not - the change to
digital recording happened about the same time as I noticed this
problem.  But I think they were OK.

I just checked an older PVR-500 recording that I have never rebuilt
the seek table for and it shows the length on playback to be over 27
hours, for a 1h02m recording.  That does not seem to be quite the same
as what you are seeing.


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