[Mesa-dev] [PATCH] nir/lower_tex: Fix minor error in YUV color conversion matrix

[Kristian Kristensen]

On Thu, May 4, 2017 at 8:50 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:

> On Wed, May 3, 2017 at 11:53 PM, Kenneth Graunke <kenneth at whitecape.org>
> wrote:
>
>> On Wednesday, May 3, 2017 11:37:52 PM PDT Johnson Lin wrote:
>> > 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.
>> > ---
>> >  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..4ef81955513e 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, -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]));
>> > --
>> > 1.9.1
>> >
>> > _______________________________________________
>> > mesa-dev mailing list
>> > mesa-dev at lists.freedesktop.org
>> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>> >
>>
>> I scooped up the various tags:
>>
>>     Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100854
>>     Reviewed-by: Eric Anholt <eric at anholt.net>
>>     Reviewed-by: Kristian H. Kristensen <hoegsberg at google.com>
>
>
Yes, the version here looks good. For reference, this fixes two Android CTS
cases:

android.media.cts.EncodeVirtualDisplayWithCompositionTest#testRenderingMaxResolutionLocally
android.media.cts.EncodeVirtualDisplayWithCompositionTest#testRenderingMaxResolutionRemotely


> Did you also scoop up a stable CC?
>
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