[FFmpeg-devel] [PATCH v2 2/2] swscale/input: clamp rgbf32 values before lrintf

Mark Reid mindmark at gmail.com
Sun Nov 14 05:24:47 EET 2021


On Sat, Nov 13, 2021 at 7:02 PM James Almer <jamrial at gmail.com> wrote:

> On 11/13/2021 11:56 PM, mindmark at gmail.com wrote:
> > From: Mark Reid <mindmark at gmail.com>
> >
> > if the float pixel * 65535.0f > 2147483647.0f
> > lrintf may overfow and return negative values, depending on
> implementation.
> > nan and +/-inf values may also be implementation defined
> >
> > clamp the value first so lrintf so, always works.
> >
> > values <=0.0f, -inf, nan = 0.0f
> > values >=1.0f, +inf      = 1.0f
> >
> > the clamping adds some performance overhead, but using a inline function
> > seems help the compiler optimize on the compiliers I tested.
> >
> > old timings
> >   213920 UNITS in planar_rgbf32le_to_uv,       1 runs,      0 skips
> >   218830 UNITS in planar_rgbf32le_to_uv,       2 runs,      0 skips
> >   223285 UNITS in planar_rgbf32le_to_uv,       4 runs,      0 skips
> >   215405 UNITS in planar_rgbf32le_to_uv,       8 runs,      0 skips
> >   208920 UNITS in planar_rgbf32le_to_uv,      16 runs,      0 skips
> >   205115 UNITS in planar_rgbf32le_to_uv,      32 runs,      0 skips
> >   212220 UNITS in planar_rgbf32le_to_uv,      64 runs,      0 skips
> >
> >   216440 UNITS in planar_rgbf32be_to_uv,       1 runs,      0 skips
> >   222450 UNITS in planar_rgbf32be_to_uv,       2 runs,      0 skips
> >   228780 UNITS in planar_rgbf32be_to_uv,       4 runs,      0 skips
> >   226900 UNITS in planar_rgbf32be_to_uv,       8 runs,      0 skips
> >   223168 UNITS in planar_rgbf32be_to_uv,      16 runs,      0 skips
> >   249340 UNITS in planar_rgbf32be_to_uv,      32 runs,      0 skips
> >   233746 UNITS in planar_rgbf32be_to_uv,      64 runs,      0 skips
> >
> >   173360 UNITS in planar_rgbf32le_to_y,       1 runs,      0 skips
> >   179970 UNITS in planar_rgbf32le_to_y,       2 runs,      0 skips
> >   182960 UNITS in planar_rgbf32le_to_y,       4 runs,      0 skips
> >   177040 UNITS in planar_rgbf32le_to_y,       8 runs,      0 skips
> >   170351 UNITS in planar_rgbf32le_to_y,      16 runs,      0 skips
> >   167136 UNITS in planar_rgbf32le_to_y,      32 runs,      0 skips
> >   165821 UNITS in planar_rgbf32le_to_y,      64 runs,      0 skips
> >
> >   181040 UNITS in planar_rgbf32be_to_y,       1 runs,      0 skips
> >   182920 UNITS in planar_rgbf32be_to_y,       2 runs,      0 skips
> >   180935 UNITS in planar_rgbf32be_to_y,       4 runs,      0 skips
> >   180897 UNITS in planar_rgbf32be_to_y,       8 runs,      0 skips
> >   179640 UNITS in planar_rgbf32be_to_y,      16 runs,      0 skips
> >   178912 UNITS in planar_rgbf32be_to_y,      32 runs,      0 skips
> >   177983 UNITS in planar_rgbf32be_to_y,      64 runs,      0 skips
> >
> > new timings
> >   228860 UNITS in planar_rgbf32le_to_uv,       1 runs,      0 skips
> >   232400 UNITS in planar_rgbf32le_to_uv,       2 runs,      0 skips
> >   237270 UNITS in planar_rgbf32le_to_uv,       4 runs,      0 skips
> >   229992 UNITS in planar_rgbf32le_to_uv,       8 runs,      0 skips
> >   222270 UNITS in planar_rgbf32le_to_uv,      16 runs,      0 skips
> >   218896 UNITS in planar_rgbf32le_to_uv,      32 runs,      0 skips
> >   216938 UNITS in planar_rgbf32le_to_uv,      64 runs,      0 skips
> >
> >   232340 UNITS in planar_rgbf32be_to_uv,       1 runs,      0 skips
> >   231830 UNITS in planar_rgbf32be_to_uv,       2 runs,      0 skips
> >   242235 UNITS in planar_rgbf32be_to_uv,       4 runs,      0 skips
> >   235210 UNITS in planar_rgbf32be_to_uv,       8 runs,      0 skips
> >   229040 UNITS in planar_rgbf32be_to_uv,      16 runs,      0 skips
> >   224996 UNITS in planar_rgbf32be_to_uv,      32 runs,      0 skips
> >   223581 UNITS in planar_rgbf32be_to_uv,      64 runs,      0 skips
> >
> >   179220 UNITS in planar_rgbf32le_to_y,       1 runs,      0 skips
> >   174790 UNITS in planar_rgbf32le_to_y,       2 runs,      0 skips
> >   182630 UNITS in planar_rgbf32le_to_y,       4 runs,      0 skips
> >   183002 UNITS in planar_rgbf32le_to_y,       8 runs,      0 skips
> >   181005 UNITS in planar_rgbf32le_to_y,      16 runs,      0 skips
> >   179390 UNITS in planar_rgbf32le_to_y,      32 runs,      0 skips
> >   192476 UNITS in planar_rgbf32le_to_y,      64 runs,      0 skips
> >
> >   195620 UNITS in planar_rgbf32be_to_y,       1 runs,      0 skips
> >   195860 UNITS in planar_rgbf32be_to_y,       2 runs,      0 skips
> >   198700 UNITS in planar_rgbf32be_to_y,       4 runs,      0 skips
> >   197252 UNITS in planar_rgbf32be_to_y,       8 runs,      0 skips
> >   195702 UNITS in planar_rgbf32be_to_y,      16 runs,      0 skips
> >   194853 UNITS in planar_rgbf32be_to_y,      32 runs,      0 skips
> >   194459 UNITS in planar_rgbf32be_to_y,      64 runs,      0 skips
> > ---
> >   libswscale/input.c | 21 +++++++++++++--------
> >   1 file changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/libswscale/input.c b/libswscale/input.c
> > index 90efdd2ffc..2a13846abe 100644
> > --- a/libswscale/input.c
> > +++ b/libswscale/input.c
> > @@ -966,6 +966,11 @@ static av_always_inline void
> planar_rgb16_to_uv(uint8_t *_dstU, uint8_t *_dstV,
> >
> >   #define rdpx(src) (is_be ? av_int2float(AV_RB32(src)):
> av_int2float(AV_RL32(src)))
> >
> > +static av_always_inline float clampf(float x, float min, float max)
>
> Use av_clipf() instead.
>

Thanks. I should have thought of that, I'll send a version


>
> > +{
> > +    return FFMIN(FFMAX(x, min), max);
> > +}
> > +
> >   static av_always_inline void planar_rgbf32_to_a(uint8_t *_dst, const
> uint8_t *_src[4], int width, int is_be, int32_t *rgb2yuv)
> >   {
> >       int i;
> > @@ -973,7 +978,7 @@ static av_always_inline void
> planar_rgbf32_to_a(uint8_t *_dst, const uint8_t *_s
> >       uint16_t *dst        = (uint16_t *)_dst;
> >
> >       for (i = 0; i < width; i++) {
> > -        dst[i] = av_clip_uint16(lrintf(65535.0f * rdpx(src[3] + i)));
> > +        dst[i] = lrintf(clampf(65535.0f * rdpx(src[3] + i), 0.0f,
> 65535.0f));
> >       }
> >   }
> >
> > @@ -987,9 +992,9 @@ static av_always_inline void
> planar_rgbf32_to_uv(uint8_t *_dstU, uint8_t *_dstV,
> >       int32_t rv = rgb2yuv[RV_IDX], gv = rgb2yuv[GV_IDX], bv =
> rgb2yuv[BV_IDX];
> >
> >       for (i = 0; i < width; i++) {
> > -        int g = av_clip_uint16(lrintf(65535.0f * rdpx(src[0] + i)));
> > -        int b = av_clip_uint16(lrintf(65535.0f * rdpx(src[1] + i)));
> > -        int r = av_clip_uint16(lrintf(65535.0f * rdpx(src[2] + i)));
> > +        int g = lrintf(clampf(65535.0f * rdpx(src[0] + i), 0.0f,
> 65535.0f));
> > +        int b = lrintf(clampf(65535.0f * rdpx(src[1] + i), 0.0f,
> 65535.0f));
> > +        int r = lrintf(clampf(65535.0f * rdpx(src[2] + i), 0.0f,
> 65535.0f));
> >
> >           dstU[i] = (ru*r + gu*g + bu*b + (0x10001 << (RGB2YUV_SHIFT -
> 1))) >> RGB2YUV_SHIFT;
> >           dstV[i] = (rv*r + gv*g + bv*b + (0x10001 << (RGB2YUV_SHIFT -
> 1))) >> RGB2YUV_SHIFT;
> > @@ -1005,9 +1010,9 @@ static av_always_inline void
> planar_rgbf32_to_y(uint8_t *_dst, const uint8_t *_s
> >       int32_t ry = rgb2yuv[RY_IDX], gy = rgb2yuv[GY_IDX], by =
> rgb2yuv[BY_IDX];
> >
> >       for (i = 0; i < width; i++) {
> > -        int g = av_clip_uint16(lrintf(65535.0f * rdpx(src[0] + i)));
> > -        int b = av_clip_uint16(lrintf(65535.0f * rdpx(src[1] + i)));
> > -        int r = av_clip_uint16(lrintf(65535.0f * rdpx(src[2] + i)));
> > +        int g = lrintf(clampf(65535.0f * rdpx(src[0] + i), 0.0f,
> 65535.0f));
> > +        int b = lrintf(clampf(65535.0f * rdpx(src[1] + i), 0.0f,
> 65535.0f));
> > +        int r = lrintf(clampf(65535.0f * rdpx(src[2] + i), 0.0f,
> 65535.0f));
> >
> >           dst[i] = (ry*r + gy*g + by*b + (0x2001 << (RGB2YUV_SHIFT -
> 1))) >> RGB2YUV_SHIFT;
> >       }
> > @@ -1021,7 +1026,7 @@ static av_always_inline void
> grayf32ToY16_c(uint8_t *_dst, const uint8_t *_src,
> >       uint16_t *dst    = (uint16_t *)_dst;
> >
> >       for (i = 0; i < width; ++i){
> > -        dst[i] = av_clip_uint16(lrintf(65535.0f * rdpx(src + i)));
> > +        dst[i] = lrintf(clampf(65535.0f * rdpx(src + i), 0.0f,
> 65535.0f));
> >       }
> >   }
> >
> > --
> > 2.31.1.windows.1
> >
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