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

Jean-Yves Avenard jyavenard at gmail.com
Sat Jun 21 00:34:10 UTC 2014


On 21 June 2014 09:41, Hika van den Hoven <hikavdh at gmail.com> 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)

in 0.26, the length reported was of the recording time, regardless of
what was stored.
In 0.27, it's actual time of what was recorded.

when recording, the backend count the number of frames written to disk
and that information is written in the database along the position in
bytes for that frame.

> 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.

when you skip forward or backward, it knows you where you're up to
frame count wise, query the database for the position in bytes between
here+skip_value and go there.

While I'm getting to is that there are many thing that could cause
what you're seeing, and not necessarily a myth one. the first one is
that the PVR-500 may not produce the right amount of frames, leading
to an incorrect calculation size, and lead to inaccurate skips

have you changed/upgraded anything other than myth when upgraded from
0.26 to 0.27?
drivers for the pvr350/500?


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