[mythtv-users] Using User Jobs to transcode HD recordings without exporting

[Yeechang Lee]

Jerry Bett <bjett80 at gmail.com> says:
> I'm running a Firewire/PVR150 system recently upgraded to 0.20
> . Most of my recordings are firewire - mpegts/ac5 (2 channel)/
> 
> Transcoding these files results in about 80% of them having broken
> audio.

Unfortunately (well, fortunately for *me*) I've never had the issue
you go on to describe in many months of transcoding HDTV recordings to
MPEG4 using mythtranscode under both 0.19 and 0.20, so can't speak to
your problem. I have had the "audio gradually goes out of sync" issue
on some transcodes
(<URL:http://www.gossamer-threads.com/lists/mythtv/users/216048#216048>),
but don't know yet whether 0.20 has fixed this issue.

> Transcoding with mencoder and -oac copy keeps the audio in ac5 and
> audio is fine. In fact, a 10gig HD recording shrinks to 1.8 gig with
> little loss of quality.

As the great American philosopher Homer J. Simpson put it, "Your ideas
are intriguing to me and I wish to subscribe to your newsletter." My
MPEG-4 transcodes are 35-40% of the original and, while this helps, I
can always use more space. What codec does the resulting transcode
use? x264? How long does it take? I find that a typical 8-10GB HD
movie takes about eight hours (admittedly on a combined
frontend/backend) to convert to MPEG-4 non-x264, while a 15-25GB movie
from HDNet or elsewhere will take a dozen hours or longer.

I know about User Jobs but haven't ever used them because I'm not
interested in exporting my MythTV recordings to DVD or AVI. I want to
keep them, just in smaller form. I don't know how to use User Jobs to
perform actions that result in files that replace the originals. (In
your example, for example, I presume that part of the solution would
be to run mythcommflag to rebuild the seektable.) In other words, I
want User Jobs that work the way mythtranscode does when called from
within MythTV.

I also want to, at some point, move to surround sound
(<URL:http://www.gossamer-threads.com/lists/mythtv/users/227841#227841>)
and so don't want to lose the 5.1 tracks as I (unbeknownst to me
before a few weeks ago) do with mythtranscode.

So, if someone can outline how to use User Jobs to a) transcode HDTV
recordings to some high-quality format, b) preserve the surround
sound, c) have the transcoded versions automatically replace the
original recording with d) proper seektables, I'd certainly appreciate
it, Jerry and I would both appreciate it!

-- 
Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US