Add BT.601 YCbCr output

[ifb]

Add planar YCbCr output (YUV444P16 or GRAY16).

[atsampson]

Thanks for this - the overall approach looks good, and it's nice to see references for the maths!

I've added a few review comments - most of these are minor stylistic things, but you can also simplify how the Configuration stuff works (by making MonoDecoder work like the PAL/NTSC decoders).

[atsampson]

Incidentally - have you tried my testsuite for ld-chroma-decoder with your changes? If you clone this repo, the try-chroma-decoder script has a fairly extensive set of tests, many of which can work using the files in ld-decode-testdata; it should produce the same output before your changes and after.

[ifb]

@atsampson Do you want changes as a separate patch or squashed into this one? If I push -f to my branch, I'm not sure what GitHub does to the merge request and your comments. I could always squash later?

[ifb]

Incidentally - have you tried my testsuite for ld-chroma-decoder with your changes? If you clone this repo, the try-chroma-decoder script has a fairly extensive set of tests, many of which can work using the files in ld-decode-testdata; it should produce the same output before your changes and after.

I cloned it a long time ago, but never used it since I didn't have any of the test LD files. I recently downloaded GGV1011 so I'd have something that's PAL, so try-chroma-decoder is running with that right now. I don't know if my laptop can decode it before I have to leave with it.

[atsampson]

This all looks good to me now - thank you very much!

I've just run my testsuite over it and it produces bitwise identical output to master for all the existing tests (so I guess I'll have to write some YCbCr tests now...).

I'd suggest squashing the revisions into your original changes in this case - it doesn't make much difference here but it makes the history a bit tidier if anyone needs to do a bisection in the future.