[mythtv] large file when recording and watching

Joseph A. Caputo jcaputo1 at comcast.net
Thu Apr 22 11:57:24 EDT 2004

On Thursday 22 April 2004 10:08, Debabrata Banerjee wrote:
> From: "Joseph A. Caputo" <jcaputo1 at comcast.net>
> > 1.0 GHz/192 MB RAM is a bit on the skimpy side for recording 1
> > stream + watching another, however, AFAIK you'd be more likely to
> > see dropped frames and/or choppy playback in that case rather than
> > increased file sizes.  Given that downgrading didn't solve your
> > problem, I'd suspect some other change in your system (signal
> > quality, new kernel, hardware changes?), but I'm afraid you've
> > exhausted my expertise in this area.
> >
> > Anyone else care to chime in?
> >
> > -JAC
> I'd say don't use RTJPEG. When I was using RTJPEG I noticed this
> issue as well. I think it's an RTJPEG bug, I noticed this in
> particular when a solid blue screen from my vcr, it sent the RTJPEG
> bitrate/cpu through the roof. (something like 64GB/hour).
> MPEG4 looks overwhelming at first, but it's cpu usage goes down as
> you lower the bitrate. 1Ghz should be fine as long as you keep the
> bitrate low. Also since that cpu has only 256k cache, you want to
> keep the frame size low. i.e. 480x480 or less, otherwise you'll find
> you need a lot of cpu power. I was running this setup on an athlon
> 700 just fine, with crop and quickdnr filters to boot.

A lot may depend on memory, though.  My Athlon XP 1600+ can just about 
do LiveTV MPEG-4 at 2200 480x480, and I have 256MB of RAM (though it's 
been suggested I could improve performance by using DDR RAM instead of 
SDRAM).  192 MB of RAM is a bit on the low side, and he didn't say what 
kind of RAM it is.  Yes, you can use MPEG-4 and keep turning the 
bitrate and/or frame size down until the performance is acceptable, but 
then the quality suffers.  It's really all a question of what is an 
acceptable picture quality for you.


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