[mythtv-users] transcode OTA HD MPEG2 -> MPEG4 w/AC3 passthru

[Paul B. Henson]

Disk space on my air2pc based HD Myth box is getting tight, so I've been
looking into transcoding to decrease the size of some of the recordings.

I've successfully transcoded some of my high-definition recordings to lower
resolution MPEG4 with considerable size savings, from 4 GB to about 800MB.
Visual quality is excellent, while not as good as the original, very
watchable particularly for less important shows.

However, there is a very noticeable difference in quality between the
original AC3 dolby digital 5.1 soundtrack and the transcoded MP3 version.

What I would really like to do is transcode the video to MPEG4 but leave
the audio alone, ending up with an MPEG4/AC3 media stream. However, there
doesn't appear to be any option in the built in transcoding implementation
to allow for this.

Reviewing the mailing list archives, I saw a couple of mentions of people
wanting similar functionality, but no resolutions.

I think it would be possible to achieve this with a user job that
transcodes using third-party utilities, but I haven't been able to find a
good source of information on setting up user jobs.

Would there be any interest in an enhancement request to allow the internal
transcoding to support audio passthru?

Also, could anyone possibly provide a pointer to a good source of
documentation for user jobs, in particular relevant to transcoding?

Thanks much...


-- 
Paul B. Henson  |  (909) 979-6361  |  http://www.csupomona.edu/~henson/
Operating Systems and Network Analyst  |  henson at csupomona.edu
California State Polytechnic University  |  Pomona CA 91768