[mythtv] Trading CPU for disk (capture using low cpu codec?)

Scott and Jill Gargash mythtv-dev@snowman.net
Wed, 11 Dec 2002 22:33:53 -0700

> Bruce Markey <bjm@lvcm.com> wrote:
> kevin thayer wrote:
> > Has anyone experimented with the trade-offs between
> > CPU usage and disk size?
> Yes, but maybe not in the way you're thinking ;-)
> Given 500MHz CPU/mobo, a 40GB disk and $150 I believe I'd
> get much better quality and more recording time by buying
> a ~2GHz CPU/mobo than I would by buying a 120GB disk.

But there are good reasons to use trade IO for CPU cycles beyond saving
$$$s.  The less you need to do in real-time the better, especially if
you don't want to have howling fans in your living room. 

And you can always perform a non-realtime recompression of the file to
get better space efficiency. And many video codecs are asymetric, i.e.,
they can require a lot more compute cycles to compress than to
decompress.  For example, when compressing mpeg-style, computing the
motion compensation vectors can take a long time if you're willing to
let it.  If you're encoding is real-time, the motion vector state space
search will be limited, while a non-realtime encoding need not be.  If
you can get better motion vectors, you can get higher quality and/or
better compression.  

And the amount of video processing can be greater than just
compression/decompression. Is anyone else using a progressive scan
monitor for playback? Some deinterlacing routines can be very compute