[FFmpeg-cvslog] avfilter/vf_premultiply : fix unpremultiply_offset for rgb input

[Martin Vignali]

ffmpeg | branch: master | Martin Vignali <martin.vignali at gmail.com> | Sat Mar 17 22:20:34 2018 +0100| [3e7fa34d3b688b9b4b5b22344e8fc27c4b53286d] | committer: Martin Vignali

avfilter/vf_premultiply : fix unpremultiply_offset for rgb input

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3e7fa34d3b688b9b4b5b22344e8fc27c4b53286d
---

 libavfilter/vf_premultiply.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavfilter/vf_premultiply.c b/libavfilter/vf_premultiply.c
index df4f26578d..4f250df3f4 100644
--- a/libavfilter/vf_premultiply.c
+++ b/libavfilter/vf_premultiply.c
@@ -272,7 +272,7 @@ static void unpremultiply8offset(const uint8_t *msrc, const uint8_t *asrc,
     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++) {
             if (asrc[x] > 0 && asrc[x] < 255)
-                dst[x] = FFMIN((msrc[x] - offset) * 255 / asrc[x] + offset, 255);
+                dst[x] = FFMIN(FFMAX(msrc[x] - offset, 0) * 255 / asrc[x] + offset, 255);
             else
                 dst[x] = msrc[x];
         }
@@ -350,7 +350,7 @@ static void unpremultiply16offset(const uint8_t *mmsrc, const uint8_t *aasrc,
     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++) {
             if (asrc[x] > 0 && asrc[x] < max)
-                dst[x] = FFMAX(FFMIN((msrc[x] - offset) * (unsigned)max / asrc[x] + offset, max), 0);
+                dst[x] = FFMAX(FFMIN(FFMAX(msrc[x] - offset, 0) * (unsigned)max / asrc[x] + offset, max), 0);
             else
                 dst[x] = msrc[x];
         }