[mythtvnz] Seek issues on currently-recording file

[Walter Somerville]

On Fri, Aug 28, 2009 at 10:24 AM, Nick Rout <nick.rout at gmail.com> wrote:
>
> On Thu, Aug 27, 2009 at 9:51 PM, Walter Somerville<walter at aaatos.net> wrote:
> > On Thu, Aug 27, 2009 at 9:25 PM, Jonathan Hoskin
> > <jonathan.hoskin at gmail.com> wrote:
> >>
> >> I too have always had this issue, since VDPAU started working + 8.10. I work around it by saving my position before seeking, escape out of playback, then hit "play from bookmark", then seeking works. After a few minutes it is no longer accurate however. Otherwise, the down arrow on my remote jumps ahead 10 minutes, which seems to line up with ad-breaks on 3 News, so just starting from the beginning again isn't so hard.
> >> Playing back a recording-in-progress seems to set a reference point on the head of the recording from the time you start watching, with any seeks treating this as a fixed end point.
> >> Jonathan
> >
> > That is possible, I guess, but it seems strange that it would do that
> > for H264 only (perhaps other digital? any DVB-S users seeing/not
> > seeing this?), and only while the file is still being written. I
> > haven't looked at the source yet, but I suspect it'll be a bit too
> > complicated to get my head around quickly...
> >
> > Perhaps also of interest would be if anyone is using DVB-T and *not*
> > seeing this?
> >
> > Walter
>
> Mythtv maintains a seektable which it uses for seeking in a recording.
> What does the seektable look like when this is happening? Compare the
> seektable for a recoding in progress and one that has completed
> recording and seeks ok.
>
> In general see here:
>
> http://www.mythtv.org/wiki/Recordedseek_table and
> http://www.mythtv.org/wiki/Repairing_the_Seektable
>
> Also you may get more info on the mythtv users list, theres a lot of
> knowledge on there, especially in relation to myth's inner workings.
>

I tried a couple of programs recording the filesize and the maximum
offset in recordedseek table for that recording.
Plotting these (uploaded to
http://www.aaatos.net/images/seekcomparison.png) shows a difference of
up to 21MB. However, I'm pretty sure that the amount by which the
playback was out was more than 21MB worth.

Is there something else I should be looking for in the seektable?

Also, is the seektable maintained by the backend?