[mythtv-users] Transcoding for best audio

Michael Stucky mike at stucky.us
Sun Jul 7 20:26:01 UTC 2013


On Sat, Jul 6, 2013 at 2:52 AM, Brenden Conte <brenden at thecontes.info>wrote:

> Thank you everyone for your feedback; it has been quite useful!
>
> Specifically about the --audiotrack argument, i was unable to get it to
> (seemingly) do anything, or find any examples of its usage in the wild.
>  From what i can tell, its looking for a number of the audiotrack to use
> (either as the primary or only, its not clear).  But no matter what i
> specify for an argument, it always creates the same mpeg.
>
> Any extra info about that argument would be welcome.
>
> -B
>
>
>

The --audiotrack argument appears to be part of the --fifodir mode of
mythtranscode. I too was unable to get it to do anything useful in any
other context. The --fifodir mode looks interesting because it outputs one
audio and one video track each to a pipe that can be used by ffmpeg (and
maybe other programs?) as input, it will --honorcutlist and cleanup damaged
frames. So it could be used as a replacement for Projectx in John's
MythDVBcut script except that the video is output in "rawvideo" format so
it must be encoded/compressed into a usable format (xvid, x264, etc.). On
my BE with an Intel i7 quad core processor a 1 hour recording took about 3
hours to transcode!! This would only be of value for something that I knew
I wanted to keep and wanted to take advantage of mythtranscode's frame
accurate cutting.

All of this is somewhat frustrating! Mythtranscode should be the best
option because it is built into MythTV but it messes with the order of
audio tracks making it troublesome to use with external players with no
option that I can find to remove unwanted audio tracks without re-encoding
the recordings. MythDVBcut does its cutting and repair at keyframes so
recordings with lots of damaged frames can be somewhat choppy but it is
fast and reliable for "clean" recordings and allows me to select audio
tracks without re-encoding.

Mike
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