[mythtv-users] MPEG2 -> MPEG2 Transcoding

[Steven Adeff]

On 3/28/06, Mark A. Hoover <mahoover at ispaceonline.org> wrote:
> > From: Preston Crow <pc-mythtv06a at crowcastle.net>
> > On Tue, 2006-03-28 at 09:36 -0500, Mark A. Hoover wrote:
> >> I've recoded some shows using a PVR-500 card that encodes to MPEG2 format.
> >> I've found that if I turn on the Lossless Transcoding toggle, that I can
> >> keep them in MPEG2 format and strip out the commercials.  However, I've
> >> been told that the resulting file can potentially have video/audio sync problems.
> >>
> >> Is this true?  And if so, is there a way to transcode the entire file and
> >> not just around the cut points?
> >
> > False.
> >
> > At least for me, I've found lossless MPEG2->MPEG2 transcoding to be
> > perfect.
> >
> > I use it on my PVR recordings and my HDTV recordings all the time.
> > Well, actually, I go through and do it every time we start getting low
> > on space.
>
> I've done a couple shows so far and haven't seen any problems, but they
> were shows that I kept just to practice commercial cutting on.  Not
> anything I planned to keep.  I was getting ready to do some shows I
> planned to keep long term when I heard that it might be an issue.  Figured
> it was better to ask and be told it's not an issue, than to find out I had
> a problem later....:)

I've "lossless" transcode commercial cuts to many shows (100+) for
both ATSC and PVR-150 MPEG2 recordings and have not once seen an audio
sync issue occur. I can with fairly good certainty say that all else
being equal no audio sync error should occur.

If you ever do see a sync issue, send an email to the Dev list, I
forget the fellows name who coded the MPEG2->MPEG2 transcoding, but
he'll ask for some more information and a sample to figure out the
problem. I know he fixed quite a few bugs for me and others while 0.19
was still in SVN.

--
Steve