> Actually, at the moment, the main question is what is the pixel
> interface like?  It appears to be DDR, very much like a single-link
> DVI transmitter.

Yes, the interface is DDR. It has a total of 9 modes (set with IN_MODE
pins). I am going to describe them in terms of pins_up[11:0] and
pins_down[11:0], which are on rising and falling edge of clockin,
respectively.
0000: 24 bit RGB.
pins_up[9:11]=g[2:4]
pins_up[4:8]=b[3:7]
pins_up[3]=g[0]
pins_up[0:2]=b[0:2]

pins_down[7:11]=r[3:7]
pins_down[4:6]=g[5:7]
pins_down[1:3]=r[0:2]
pins_down[0]=g[1]

0010: 15 bit RGB
pins_up[9:11]=g[0:2]
pins_up[4:8]=b[0:4]

pins_down[7:11]=r[0:4]
pins_down[4:5]=g[3:4]

0001: 16 bit RGB
pins_up[9:11]=g[0:2]
pins_up[4:8]=b[0:4]

pins_down[7:11]=r[0:4]
pins_down[4:6]=g[3:5]

0101: 16 bit YCrCb
pins_up[4:11]=Cr/Cb[0:7] (alternating pixels)

pins_down[4:11]=y[0:7]

0100: 24 bit YCrCb
pins_up[4:11]=Cr[0:7]
pins_up[0:3]=Cb[4:7]

pins_down[4:11]=y[0:7]
pins_down[0:3]=Cb[0:3]

1000: Alt. 24 bit RGB
pins_up[8:11]=g[0:3]
pins_up[0:7]=b[0:7]

pins_down[4:11]=r[0:7]
pins_down[0:3]=g[4:7]

0110: Alt. 16 bit YCrCb
pins_up[0:7]=Cr/Cb[0:7] (alternating pixels)

pins_down[0:7]=y[0:7]

1100: Alt. 24 bit YCrCb
pins_up[8:11]=y[0:3]
pins_up[0:7]=Cb[0:7]

pins_down[4:11]=Cr[0:7]
pins_down[0:3]=y[4:7]

I am not sure about this, but it says the following:
The CX25874/5 encoder can generate following types of video outputs:
Composite
(CVBS), S-Video (separate Luma [Y] and Chroma [C] channels), YUV,
Component
480i YCRCB, VGA-style RGB, Euro SCART, Component (YPRPB) for HDTV, or
RGB for HDTV. These outputs are selected by the OUT_MODE[1:0] register
bits in
combination with the HDTV_EN and EN_SCART bits.
It appears that once the data has been entered, it can basically be
converted to any format under the sun and outputted. There are many,
many example configurations in the datasheet if we feel like looking for
them.

nick



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