vo_gpu: fix green shit with float yuv input

This was incorrect at least because the colorspace matrix attempted to
center chroma at (conceptually) 0.5, instead of 0. Also, it tried to
apply the fixed point shift logic for component sizes > 8 bit.

There is no float yuv format in mpv/ffmpeg yet, but see next commit,
which enables zimg to output it. I'm assuming zimg defines this format
such that luma is in range [0,1] and chroma in range [-0.5,0.5], with
the levels flag being ignored. This is consistent with H264/5 Annex E (I
think...), and it sort of seems to look right, so that's it.

1 files changed, 2 insertions, 0 deletions

diff --git a/video/csputils.h b/video/csputils.h
index fc6f04db6a..dfc2a569cc 100644
--- a/video/csputils.h
+++ b/video/csputils.h
@@ -162,6 +162,8 @@ struct mp_csp_params {
     float gamma;
     // discard U/V components
     bool gray;
+    // input is already centered and range-expanded
+    bool is_float;
     // texture_bits/input_bits is for rescaling fixed point input to range [0,1]
     int texture_bits;
     int input_bits;