libdv & color conversion

[Stefan L. <lu...@be...>]

I think there is something wrong with color conversion in libdv.

The value of impact[3] is calculated but never used.

From documentation of Brooktree Bt848 p. 41 color conversion should be:
    R = 1.164(Y - 16) + 1.596(Cr - 128)i
    G = 1.164(Y - 16) - 0.813(Cr - 128) - 0.391(Cb - 128)
    B = 1.164(Y - 16) + 2.018(Cb -128)

So impact values should be calculated the following way
    impact[0] = 409 * cr;
    impact[1] = 100 * cb;
    impact[2] = 208 * cr;
    impact[3] = 516 * cb;

Finally I had to exchange R and B value assignment to get good colors.
    - This is only checked with a PAL datastream.
    - My display works with 16 bit color depth.

The following patch includes these modification for both YUV411 and
YUV420. 

-- 

mfg

  Stefan Lucke (lu...@be...)