swscale/utils: Fix intermediate format for cascaded alpha downscaling

Fixes Ticket4926 Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
9 years ago · b83d8be6bf
parent 4bec36f98c
commit b83d8be6bf
1 changed files with 3 additions and 0 deletions
--- a/libswscale/utils.c
+++ b/libswscale/utils.c
@ -1803,6 +1803,9 @@ fail: // FIXME replace things by appropriate error codes
        int tmpH = sqrt(srcH * (int64_t)dstH);
        enum AVPixelFormat tmpFormat = AV_PIX_FMT_YUV420P;

+        if (isALPHA(srcFormat))
+            tmpFormat = AV_PIX_FMT_YUVA420P;
+
        if (srcW*(int64_t)srcH <= 4LL*dstW*dstH)
            return AVERROR(EINVAL);