[FFmpeg-devel] [PATCH] swscale/input: clamp rgbf32 values between 0, 1 before scaling

mindmark at gmail.com mindmark at gmail.com
Sun Nov 7 07:52:21 EET 2021


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 values between 0,1 before scaling, so lrintf
always works.

values <=0.0f, -inf, nan = 0.0f
values >=1.0f, +inf      = 1.0f
---
 libswscale/input.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/libswscale/input.c b/libswscale/input.c
index 336f957c8c..ea50c9de5c 100644
--- a/libswscale/input.c
+++ b/libswscale/input.c
@@ -964,7 +964,7 @@ static av_always_inline void planar_rgb16_to_uv(uint8_t *_dstU, uint8_t *_dstV,
 }
 #undef rdpx

-#define rdpx(src) (is_be ? av_int2float(AV_RB32(src)): av_int2float(AV_RL32(src)))
+#define rdpx(src) (FFMIN(FFMAX(is_be ? av_int2float(AV_RB32(src)): av_int2float(AV_RL32(src)), 0.0f), 1.0f))

 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)
 {
@@ -1013,17 +1013,16 @@ static av_always_inline void planar_rgbf32_to_y(uint8_t *_dst, const uint8_t *_s
     }
 }

-#undef rdpx
-
 static av_always_inline void grayf32ToY16_c(uint8_t *_dst, const uint8_t *_src, const uint8_t *unused1,
                                             const uint8_t *unused2, int width, uint32_t *unused)
 {
     int i;
     const float *src = (const float *)_src;
     uint16_t *dst    = (uint16_t *)_dst;
+    int is_be = 0;

     for (i = 0; i < width; ++i){
-        dst[i] = av_clip_uint16(lrintf(65535.0f * src[i]));
+        dst[i] = av_clip_uint16(lrintf(65535.0f * rdpx(src + i)));
     }
 }

@@ -1033,12 +1032,15 @@ static av_always_inline void grayf32ToY16_bswap_c(uint8_t *_dst, const uint8_t *
     int i;
     const uint32_t *src = (const uint32_t *)_src;
     uint16_t *dst    = (uint16_t *)_dst;
+    int is_be = 1;

     for (i = 0; i < width; ++i){
-        dst[i] = av_clip_uint16(lrintf(65535.0f * av_int2float(av_bswap32(src[i]))));
+        dst[i] = av_clip_uint16(lrintf(65535.0f * rdpx(src+ i)));
     }
 }

+#undef rdpx
+
 #define rgb9plus_planar_funcs_endian(nbits, endian_name, endian)                                    \
 static void planar_rgb##nbits##endian_name##_to_y(uint8_t *dst, const uint8_t *src[4],              \
                                                   int w, int32_t *rgb2yuv)                          \
--
2.29.2



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