[PD] second monitor for GEM

cgc cgc at humboldtblvd.com
Fri Feb 13 03:45:41 CET 2004

On Feb 12, 2004, at 5:40 PM, beau wrote:

> It would be really cool if gem could output the Gem window fullscreen 
> via
> firewire?

Yeah, cool if you like your performance severely degraded.  Here's what 
is required:

1) Render everything into the GPU back-buffer (pretty taxing in and of 

2) Read the contents of the back-buffer from the video card to main 
memory (only OSX does this at speeds even remotely approaching fast)

3) Convert RGB(A) buffer contents into 4:1:1 YUV (basically a 3x3 
matrix multiply)

4) Compress into DV25 (and possibly have to interlace to 60 

5) Push the pixels from main memory over the kernel boundary and onto 
the FW device.

Add to that the limitations of a fixed 720x480/576 frame size, 
interlaced output, and the fact that not being able to meet 25 or 29.97 
fps makes things look noticeably wrong, and it sounds rather 
unappealing doesn't it?  It is possible to do, but honestly the time 
and effort to do so would be much better directed to other areas of GEM 
right now (documentation, optimizations, achieving functional parity 
between platforms, actually releasing a version to the public, etc.).


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