[mythtv-users] Transcoding issues. SD is fine, HD fails

[Jim Stichnoth]

On Tue, Apr 13, 2010 at 6:35 PM, Neil Salstrom <salstrom at gmail.com> wrote:
> Is Transcoding broken in 0.23?  I'm running 0.23-fixes (on Debian
> Lenny) and the other day decided to try and save some space by
> transcoding some recordings.  I'm using a HDHomerun (at one point
> Comcast QAM and now OTA).  I transcoded a dozen or so Mythbusters (SD,
> 480i) and everything was great.  File size was much smaller and the
> quality was great (this was using the "Autodetect" option).
>
> I then went a head and transcoded many more shows (again using
> autodetect)... This time they were HD (both 720p and 1080i).  Uh oh...
> Not good!  The video is now slow and juddery and they sound like
> SLOOOOOWWWWW tape being played.
>
> This only happens with HD.  All the Autodetect options are default.
>
> I have a feeling I just lost all my Simpsons....
>
> Anyone else experience this?  I've never debugged before but if anyone
> has any suggestions on what I can do to try and figure this out I'm
> game!
>
> Neil

Are you using an ION-based frontend?  Are you transcoding to MPEG4?
The ION does not do hardware decoding of files created by MPEG4
transcoding (though the ION 2 supposedly does).  This leaves the
not-so-powerful Atom CPU to do the decoding.  The Atom is just
powerful enough to decode SD MPEG4, but not HD.

The same will be true for any under-powered CPU, unless you have ION 2.

Run "top" during playback to see how much CPU is being utilized.

Jim