[mythtv] mythtranscode dropping audio?

Gary Dezern gary at garyndenise.org
Wed May 31 14:44:14 UTC 2006

Updated to trunk last night, and now I'm finding that if I run lossless
MPEG2 mythtranscode on the same file twice, the audio is lost. 
Actually, it appears that if the audio is in mp3 or mp2 format, I lose the
audio on the first transcode, and if it's in ac3 format, I lose it on the

Let me back up...

What commandline
parameters does the BE use when calling mythtranscode for lossless
MPEG2?  Once I have that, I can (hopefully) repeat the problem
outside the backend, and repeat it with a small sample - and post a bug
request with logs.


I very frequently
will pull files off my direcTV tivo, and reencode them to mpeg2 (via
tmpegExpress) and then import them into mythtv.  When I re-encode
them, I transform the audio from *whatever* tivo puts in there to AC3
2/0.  Then I use the contrib script to import those videos into
mythtv.  I've found that by using the lossless transcode in myth that
I can also take advantage of commercial flagging, cut editing, etc. 
However, sometimes the files right after import don't play entirely too
well with myth, so my habit has been to (lossless) transcode them
immediately after importing them.

Then, because I have 2
children who scream often, or because I want to cut out commercials or
whatever, I do a second lossless transcode.  It's after this second
transcode that I suddenly find the audio has gone missing.  

In the logs, when I do a lossless transcode, I'm accustomed to see the
file size grow very slightly.  I figure this is due to fixing up
*whatever*.  When the second lossless transcode runs, assuming no
cuts, the file size drops quite a bit.  Example:

2006-05-31 08:00:34, Transcode Starting,   Teletubbies "Animal
Rhythms": 504.5 MB (Autodetect)

2006-05-31 08:01:03,
Transcode Finished, Teletubbies "Animal Rhythms": 506.7 MB

2006-05-31 08:10:59, Transcode Starting,
Teletubbies "Animal Rhythms": 506.7 MB (Autodetect)

2006-05-31 08:11:26, Transcode Finished, eletubbies "Animal
Rhythms": 476.3 MB (Autodetect)
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