[mythtv-users] new video2ipod script released!

Jeff Simpson jeffsimpson at alum.wpi.edu
Sat Mar 8 03:33:02 UTC 2008


>  I just finished encoding with 0.6 and it didn't work that great..
>  The I encoded an HD (720p) show. The show was 1 hour 9 mins and 55 seconds
>  long.
>  The video conversion processed fine and it even stayed in the 16:9 format.
>  It is the audio that is screwy.
>  At the beginning the audio seems fine althou it is out of sync by a few
>  milliseconds. That's fine, I can work with that.
>  At 28 mins 22 seconds the audio suddenly it starts going double time, or
>  faster, and it sounds like I'm watching an old chipmunks show. But it is way
>  too fast to actually pick out the words. And, due to the faster audio, the
>  audio stream stops at 42 mins 12 seconds.
>  Through all of this the video came out crystal clear. If we can figure out
>  this audio issue this script will be sweet.

Hmm, that is a little odd. Upgrading to 0.7 probably won't fix that,
as there's no change at all to the ffmpeg command call.

All the video+audio processing is done by a single ffmpeg command - if
you can figure out what about that command is causing the problem,
perhaps it can be fixed. Is it possible that there's a glitch in the
video file that works fine on playback but hangs ffmpeg up? Does the
log file show any weird errors in the ffmpeg portion?

I've considered adding in an optional step - running the video through
mencoder as a cleaner. mencoder does a really good job of removing all
the glitches in the video and it does it fairly quickly without
changing the format. I left a comment in the code that shows the
command I used to "sanitize" a video file, if you want to test that.

I'd also check to see how it looks and sounds in mpeg4. h264 in my
experience really isn't all it's cracked up to be. Filesizes and
quality are almost indistinguishable from the mpeg4 versions. Could be
that I am looking at SD TV, though, which has a fair amount of noise
inherent in analog.

>  I'm not sure how fully tested the multiple threads option is, so on my new
>  test I'll go back to 1 thread.

Yeah, that might be a good idea to test. ffmpeg seems to do weird
things if you set threads sometimes.

 - Jeff


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