[mythtv] transcoder documentation.

[Chris Petersen]

> 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?

>  It shouldn't be too difficult to get rid
> of most of the decodes, since the transcoder usually knows ahead of time
> whether a frame needs to be decoded or not.  It has been something I've
> been planning on for a while, and I will eventually get around to adding
> that feature.

Well, the first part here may explain why it's slow

> A note of caution: I wouldn't delete your old files immediately.  The
> method I chose for adjusting key-frames due to the commercial cut works
> great for me, but it will generate files which are incompatible with
> mencoder (until the mencoder patch is updated).

noted.

> 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.

> 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?

Oh, and a nice commandline option would be to specify an output
filename...

-Chris