[mythtv] encoding vs decoding

Michael J. Hammel mythtv at graphics-muse.com
Mon Oct 13 13:06:51 EDT 2003


According to the docs, a Celeron 450 takes about 2% CPU to encode a
stream but takes about 80% to decode.  Is that a typo or is that about
right?  The reason I ask is that my Celeron 560MHz (according to
/proc/cpuinfo) seems to be thrashing when viewing scaled video, such as
when I'm looking at the "Delete Recordings" page and the preview is
enabled.  I don't get the impression that such thrashing is going on
when I'm watching a full screen version of the recording, but it may be
happening there as well.

On a related note, I've been noticing some problems with recordings. 
Most of my recordings happen late at night, with and without the
frontend running (the desktop is normally running, however).  In the
morning I'll notice the hard disks whirring away, busy as a beaver and I
can no longer get into the machine either on the console/X or via ssh. 
I have to do a hard reset.  I've turned off transcoding which I felt
might be causing this problem due to a slow CPU since some recordings
are going on while (I think) transcoding was being performed on a just
recorded show.  I do notice that the problem seems to happen when I'm
getting full on disk space.  Perhaps there is a formula for determining
how full to allow the disk or buffers to fill to help prevent this sort
of thrashing?  

Finally, does transcoding happen as a stream or does a copy of the
recording have to be created before transcoding is performed on it? 
After transcoding, does the original recording get deleted
automatically?  I didn't notice a configurable option for this but maybe
I missed it.
-- 
Michael J. Hammel <mythtv at graphics-muse.com>



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