Re: Question about the video device driver

On Mon, 10 Jan 2000, Shuangjun Zhu wrote:

quoted

  What format is the hardware buffer in?  What macroblock
size?

For the MPC823 FADS board, video controller is in the CPM, part of 
the CPU, and video encoder is ADV7176, video memory is map to 
the system memory.  It can support NTSC/PAL display.

MPC823 can support RGB and YCr Cb, but for Analog Devices ADV7176
video encoder,  it can only support 4:2:2 YCr Cb(CCIR 601) format.

I do not know what the macroblock's meaning is.

  I meant the Cr and Cb sampling intervals.  It's 4:2:2 so it's
2x1 pixel blocks.  That means you have to do some sort of
shadowfb method since X requires that you can read back
the data without loss.  If there were Cb and Cr samples for each
luma, then you could have used a StaticColor visual and rendered
directly into the framebuffer.  StaticColor is like pseudocolor
but with a fixed lookup table.


			Mark.


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