ffplay: detect when the created overlay buffers are not valid for the wanted overlay height

Fixes cases when the picture height was bigger than the maximum supported
overlay height...
Signed-off-by: Marton Balint <cus@passwd.hu>

ffplay.c

@@ -1504,6 +1504,7 @@ display:
 static void alloc_picture(VideoState *is)
 {
     VideoPicture *vp;
+    int64_t bufferdiff;
 
     vp = &is->pictq[is->pictq_windex];
 
@@ -1515,7 +1516,8 @@ static void alloc_picture(VideoState *is)
     vp->bmp = SDL_CreateYUVOverlay(vp->width, vp->height,
                                    SDL_YV12_OVERLAY,
                                    screen);
-    if (!vp->bmp || vp->bmp->pitches[0] < vp->width) {
+    bufferdiff = vp->bmp ? FFMAX(vp->bmp->pixels[0], vp->bmp->pixels[1]) - FFMIN(vp->bmp->pixels[0], vp->bmp->pixels[1]) : 0;
+    if (!vp->bmp || vp->bmp->pitches[0] < vp->width || bufferdiff < vp->height * vp->bmp->pitches[0]) {
         /* SDL allocates a buffer smaller than requested if the video
          * overlay hardware is unable to support the requested size. */
         fprintf(stderr, "Error: the video system does not support an image\n"