The matrix used for YCbCr to RGB is listed in Wiki https://en.wikipedia.org/wiki/YCbCr; There is minor error in the matrix constant: 0.0625=16/256 should be 16.0/255, and 0.5=128.0/256 should be 128.0/255. Note that conversion from a 0-255 byte number to 0-1.0 float is to divide by 255 instead of 256. That's we get 255=1.0f. By the constant change we can see the CSC result is bit aligned with Wiki conversion result and FFMPeg result. Otherwise in some situation, there will be one bit difference
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100854 --- src/compiler/nir/nir_lower_tex.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/compiler/nir/nir_lower_tex.c b/src/compiler/nir/nir_lower_tex.c index 352d1499bc8d..385739a56a71 100644 --- a/src/compiler/nir/nir_lower_tex.c +++ b/src/compiler/nir/nir_lower_tex.c @@ -244,9 +244,9 @@ convert_yuv_to_rgb(nir_builder *b, nir_tex_instr *tex, nir_ssa_def *yuv = nir_vec4(b, nir_fmul(b, nir_imm_float(b, 1.16438356f), - nir_fadd(b, y, nir_imm_float(b, -0.0625f))), - nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -0.5f)), 0), - nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -0.5f)), 0), + nir_fadd(b, y, nir_imm_float(b, -0.0627451f))), + nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -0.50196078431f)), 0), + nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -0.50196078431f)), 0), nir_imm_float(b, 0.0)); nir_ssa_def *red = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[0])); -- 1.9.1 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
