[mythtv-users] Preserving HDTV AC3 audio stream whilst transcoding

Kyle Rose krose+mythtv at krose.org
Thu Nov 18 13:55:55 UTC 2004


> Xine and myth use identical amounts of cpu on my xp1800+ when using
> Xv -- ie, around 75% (and X using around 20% for both) when decoding
> 1080i.  Both play back mostly smoothly, with a glitch every 10
> seconds or so (ie, the CPU is very marginal for what it's doing).
> If you're seeing a difference, you have a configuration issue.  What
> that may be, I don't know, since you've not done much besides whine.

I recall in 10th grade believing that every problem my users (of a BBS
system software) were experiencing was their fault because I didn't
see it.  I have since learned that is hardly ever true, especially
when more than one person is reporting the problem.

To me, the calculus is very simple.  With xine, a particular HDTV
broadcast leaves the CPU 71% idle; with mythtv, that same broadcast
leaves my CPU only 48% idle.  That 23% is disappearing into mythtv
somewhere.  If this results from a configuration problem, I am forced
to conclude from this evidence that it is in mythtv's configuration
because some other piece of software can handle efficient playback on
my machine just fine.

I'd love to understand the logic in alternate arguments.

FWIW, if I can figure out what parts of myth's configuration scripts
are not vestigal, I will attempt to gprof it to find out exactly where
myth is screwing up.  Until then, I'm grateful I have a machine that
is 3x more powerful than it should need to be.

Cheers,
Kyle


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