On Friday, April 28, 2017 3:02:01 PM PDT Eric Anholt wrote: > Johnson Lin <johnson....@intel.com> writes: > > > 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)); > > Could we use 16.0/255.0 and 128.0/255.0, instead of magic-looking > numbers? With that, it will be: > > Reviewed-by: Eric Anholt <e...@anholt.net> >
Also, please start the commit title with "nir: "
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