[mythtv-users] Re: Re: Best video capture resolution for output to TV?

[Ray Olszewski]

At 04:12 PM 5/16/2003 -0700, Bruce Markey wrote:
[...]
>Allen T. Gilliland IV wrote:
>>And practically speaking you
>>wouldn't want to exceed 720 because your playback
>>image would be in a strange ratio.
>
>But 480x480 or 544x480 aren't 4:3 either. MythTV scales
>to fullscreen so assuming your TV or monitor is 4:3,
>any recording resolution will look correct. For TV in a
>window, there is a Setup->Playback checkbox to force
>4:3 regardless of the recording resolution.

This raises a related but distinct issue -- to what extent does encoding in 
a non-4:3 ratio complicate playback? I ask because I've noticed that on my 
Myth system, if I run xine and play back DivX video I've encoded at a 4:3 
ratio, playback uses about 5% of CPU. But if in Myth I play back video that 
Myth has recorded at its default 3:3 ratio, rescaling it to 4:3, the 
decoding uses almost 35% of CPU.

Why the difference? Is it connected to the rescaling? Is the Myth codec 
just that much less efficient than xine's? Is the larger image size 
(480x480 in Myth, 320x240 in xine, so Myth is 3 times the pixels of xine) 
enough to cause a 7x increase in CPU use? Is it a combination of all these 
things?