[mythtv-users] DVB-T playback thru PVR, odd ff/rw problem

Torsten Schenkel mythtv at isl.mach.uni-karlsruhe.de
Thu Jul 29 08:30:28 EDT 2004

Am Do, den 29.07.2004 schrieb Stephen Longhurst um 12:04:


> > Problem:

> > However, any ff/rw when playing back Nova-T recordings causes an a/v
> > pause followed by some HDD thrashing (whilst it seeks in the file I 
> > assume) then play returns at the desired point. So ff/rw does work, just
> > not near-instantly like with the PVR recordings.

> > Furthermore, the on-screen time display describes Nova-T recordings as
> > (e.g.) "00:05:06 of 1862:44:12" - something clearly not right there!

I have (a) similar problems here when playing plain mpeg2 files through
the pvr350. I only have the pvr for output, so I use mythtv %s as play
command in mythvideo. This works fine but for the problems you describe.
As far as I know this is related to the way myth does it's seeking.
There has to be a timestamp every now and then which is stored in the
database. This of course is missing if I use mythtv to play an arbitrary
mpeg file. I wondered if it would be possible to change mythtv in a way
so that it seeks the mythtv way on it's own recordings but like any
other video player (mplayer) in self indexed video files, like mpeg2 or
indexed avi. This and a dvd-mode for the internal player would be just
what's missing to make the mythbox experience that of a genuine
integrated system. I don't like the discrepancy between tv/watch
recording mode and video/dvd mode even on the second frontend on my

So is there some way to integrate that? I know, I could do it myself,
but am only able to code some f77 and f90. No c, no c++ and no qt at
all. Well some perl and bash/sed skripting, there is. Since mythtv's
internal player uses ffmpeg there shoud be sufficient support for all
relevant video formats. What about libdvdnav? Any plans out there? 

> > My thoughts so far:
> > Initially I suspected some GOP/mythcommflag issue preventing direct 
> > seeking - but then discovered remote mythfrontend was okay. I do know
> > that streams from the PVR and Nova-T card are pulled in PS and TS format
> > respectively - some issue here perhaps, but again remote playback is
> > fine (and I think TS is converted to PS on saving anyway).

For the recordings made by mythtv I guess mythcommflag should do the
trick of reindexing the file in the db. At least it did for me for some
files that didn't have the indices in the db due to a mysql error.

> > This leads me to suspect the PVR's ivtv-fb driver, but how can it affect
> > mythtv's seeking and estimation of recording length?! That doesn't make
> > sense to me. This is why I'm stumped!
> On my machine, I can switch pretty easily between PVR-350 TV output
> and it's Nvidia MX440 TV output (both are output to my TV at the same
> time through different TV inputs).  I'll give the Nvidia a try and see
> if that makes any difference.

It seems to do here. On the vga I get a total time that at first is
fluctuating and the converges to the actual time the longer the file
plays. Seems like mythtv is calculating the time from the mean bitrate.


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