[mythtv] transcoder documentation.

Geoffrey Hausheer ou401cru02 at sneakemail.com
Sat Aug 9 19:53:04 EDT 2003

On Sat, 09 Aug 2003 12:21:08 -0700, "Chris Petersen
lists-at-forevermore.net |mythtv/1.0-Allow|"
<o8f8hesx3k0t at sneakemail.com> said:
> > To use this feature you must specify a profile which is identical to the input
> > format, and use --honorcutlist.
> Hmm, so if I've changed my profile since encoding (altered the bitrate,
> added better-mpeg4 encoding that wasn't available in earlier versions),
> it won't work?  Is there any way to tell what methods were used on the
> recording so I can recreate the old profile?

The only thing that the transcoder checks is that the stream formatis the
same (i.e if it is mpeg4 or rtjpeg, and whetehr mp3 is on or off).  Thus
you could bork stuff if you changed the mp3 encoding bitrate, but
otherwise it won't matter (I don't know if mpeg4 options like qpel will
make a stream broken or not, but I wouldn't expect so)

I know of no way to recreate a profile, but I could probably add a switch
to use the same profile as in the recorded file (assuming enough info

> > Of course, there is no MPEG2 encoder in mythtv, so the 'remove-commercial'
> > part won't work unless also transcoding to MPEG4 or RTJpeg. 
> You should take a look at bbmpeg (bsd license, I think) - the only
> recent port I know of is for windows, or I'd be using it in linux, but
> it has a very-functional mpeg cutter/joiner.

Isaac has basically said he has no interest in a software MPEG2 encoder
in mythtv.  Adding a special encoder for commercial cutting is
non-trivial, and not something I have much interest in doing.

> > Oh yeah, and I don't recommend using mythtranscode from the command-line
> > if your goal is to remove the commercials
> I want to make a few test runs before running it from myth.  from
> reading the docs, i'm expecting the transcoded file to replace my
> original.  Or does it just keep the .tmp file?

mythtranscode just takes in a nuv and writes out a .tmp file.  the
mythbackend takes care of renaming and whatnot.

> Oh, and a nice commandline option would be to specify an output
> filename...
I see no good reason to do this.  The files that come out of
mythtranscode aren't useful to mythtv without modifying the database, and
other uses (for example mkmovie) should be able to deal with the files as
they are.  mythtranscode isn't meant to be run by the user, it should
instead be run by some other program, and I don't see a need to support
different filenames in mythtranscode.  However, I'm not direly against

  Geoffrey Hausheer

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