[mythtv-users] Transcoding Advice

[Christopher Meredith]

On Thu, Jan 6, 2011 at 12:50 PM, Steven Adeff <adeffs.mythtv at gmail.com>wrote:

> On Tue, Jan 4, 2011 at 10:40 PM, E. Westbrook
> <mythtv-users at westbrook.com> wrote:
> > On Tue, Jan 4, 2011 at 15:05, Steven Adeff <adeffs.mythtv at gmail.com>
> wrote:
> >>
> >> I'm actually trying to find a good way to do this with being able to
> >> cut out the commercials.
> >
> > If mencoder is a workable alternative for you, apparently someone once
> had
> > some luck creating EDL (edit decision list) files from MythTV cutlist
> data
> > pulled out of the database.  I haven't tried the approach, or the script
> > (and would probably use the perl bindings instead, if I did), but did
> find
> > it interesting.
> >
> > http://www.mythtv.org/pipermail/mythtv-users/2005-July/094886.html
> >
> > $0.02,
> > EW
>
> I'd be happy just to find something that will let me cut the
> commercials out with a 1:1 transcoding, like how Myth's internal was
> when it worked.
>
> The problem I have now is that for whatever reason ProjectX no longer
> lets me choose cut points by frame, and I get a constant audio shift
> when trying to use avidemux, a shift value that varies from mpeg to
> mpeg, and I can't seem to find a consistent way to know what that
> shift is.
>
>
A little while ago I tried everything I could think of to get workable
lossless HD-PVR transcoding. I found that the only way to avoid audio shift
using avidemux was to ensure that the recording had 6-channel AC3 audio. I
included a function in my user job that would check if the source file had
6-channel AC# and if not, convert it. Although hackish, this resulted in
fairly consistent success IIRC. That said, the avidemux method still isn't
frame accurate and I ended up abandoning it. Now, I have mt recording
profile set to use the HD-PVR in CBR mode its highest setting, then
transcode to MPEG2. Although lossy, this makes the recording compatible with
the existing myth tools, including mythtranscode for frame-accurate
commercial cutting. I have a little 26" 720p display and from the couch, I
can't see any difference between the original and MPEG2-transcoded files. If
you're interested, drop me a line and I'll send you my scripts.
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