[mythtv-users] X and PVR 350

Dan Wilga dwilga at MtHolyoke.edu
Fri Jan 28 14:49:20 EST 2005


At 2:52 PM +0000 1/28/05, Chris Martin wrote:
>Currently I can use:
>
>  ivtvfbctl -alpha 0; mplayer -fs -zoom -quiet -vo ivtv %s; ivtvfbctl 
>-alpha 255
>
>which gives me the wrong size video

Like I said, your source video is the wrong size. In this case, 
mplayer is foregoing the scaling and just telling the 350 to decode 
and display what it can. That's why you only get part of the image.

As soon as you add scaling in, so you can see the whole frame, the 
350 is no longer doing the decoding internally. Instead, the computer 
has to:

1. Decode and scale the first frame
2. Copy it to the 350's framebuffer
3. Decode and scale the next frame
4. Hope that Steps 2 and 3 took less than 1/60 (or 1/50 for PAL) of a second
5. Copy the second frame to the FB

The problem is Step 2. Copying from system RAM to the framebuffer is 
relatively slow, as you can see when you do something as simple as 
open a full-screen JPEG. You can see it copy, even on a fast machine, 
which means it's probably taking about 1/20 of a second.
-- 
Dan Wilga                                         dwilga at mtholyoke.edu
Web Administrator                             http://www.mtholyoke.edu
Mount Holyoke College                                Tel: 413-538-3027
South Hadley, MA  01075            "Who left the cake out in the rain?"


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