[mythtv-users] Strange X CPU usage for 720p input streams
Michael T. Dean
mtdean at thirdcontact.com
Wed Jun 21 01:29:34 UTC 2006
On 06/20/2006 12:40 AM, Indulis Bernsteins wrote:
>>X still has high CPU watching
>>recorded 720p programs. Not quite sure why that would be.
>Makes sense- 720P sends out 720 lines *every* frame, 1080i sends out 1080
>lines every 2 frames (ie 540 lines every frame).
Actually, that's 540 lines/field with 2 fields per frame.
> From a a processing
>point of view, 720p is like 1440i, so you'd expect about 30% more CPU to
>decode and cope with the video data coming in.
Of course, 720p60 is 1280x720 pixels/frame @ 60 frames/second = 55296000
pixels/second. And, 1080i60 is 1920x1080 pixels/frame @ 30
frames/second (i.e. 1920x540 pixels/field @ 2 fields/frame @ 30
frames/second) = 62208000 pixels/second.
Therefore, 720p60 is about 89% as many pixels as 1080i60. Or, 1080i60
is 112.5% the number of pixels of 720p60...
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