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nir/lower_tex: Fix minor error in YUV color conversion matrix

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The matrix used for YCbCr to RGB is listed in:

    https://en.wikipedia.org/wiki/YCbCr

There was an error in converting the offsets from integers to unorm
values: 0.0625=16/256 should be 16.0/255,and 0.5=128.0/256 should be
128.0/255.  With this fix, the CSC result is bit aligned with wikipedia's
conversion result and FFMPeg's result.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100854
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
This commit is contained in:
Johnson Lin
2017-05-04 14:37:52 +08:00
committed by Kenneth Graunke
parent da665d22f5
commit a6fb943f3e
1 changed files with 3 additions and 3 deletions
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6
src/compiler/nir/nir_lower_tex.c
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@@ -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, -16.0f / 255.0f))),
nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -128.0f / 255.0f)), 0),
nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -128.0f / 255.0f)), 0),
nir_imm_float(b, 0.0));
nir_ssa_def *red = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[0]));