[mythtv-users] Mythtranscode (lossless cutting commercials) and audio track names

[Michael Stucky]

On Sat, Aug 3, 2013 at 4:31 PM, Ian Evans <dheianevans at gmail.com> wrote:

> Using 26-fixes with the .25 mythtranscode. Doing lossless cuts to take
> commercials or pledge drives out to save a few gigs here and there until I
> can get a new drive.
>
> Just curious if it's a setting I'm missing or does mythtranscode strip out
> the audio track names?
>
> One of my PBS channels broadcasts older shows in English 2ch and Spanish
> Castilian 2ch. After the lossless transcode I end up with two tracks that
> are both Undetermined 2ch.
>
> Is there anyway for mythtranscode to leave the audio track names alone?
>
> Thanks!
>
>
> It is my understanding that the problem is the conversion of the mpeg2
"ts" stream to mpeg2 "ps". Any process (mythtranscode, projectx, ffmpeg,
etc.) that does this conversion will loose the language identification. As
a result most non-Myth video players and sometime MythTV itself have
trouble selecting the "correct" or "best" audio track.

The only solution I have found to this problem is remove unwanted audio
track(s) before mythtranscode is run. Fortunately, ffmpeg/mythffmpeg allows
you to specify which tracks to include and by default will copy the first
video and first audio track as follows:

  mythffmpeg -i INFILE -vcodec copy -acodec copy -f mpegts OUTFILE

Will create a copy of a recording (INFILE) named OUTFILE that is still in
mpeg2 "ts" format with only one video and one audio track. If you need an
audio track other than the first one you can use the -map option as follows:

 mythffmpeg -i INFILE -map 0:0 -map 0:2 -vcodec copy -acodec copy -f mpegts
OUTFILE

Will create a copy of a recording (INFILE) named OUTFILE containing the
first and third tracks (the first track should be the video and the third
track should be the second audio track).

Now you can flag ads or any other content you want to remove and run
mythtranscode without concern about the audio track selection.

I included a sample of the script that I run as a USERJOB for everyone of
my recordings in this thread (it is near the end),
http://www.gossamer-threads.com/lists/mythtv/users/546934

Mike
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