Fix disposal method issue

Author: jagraff

libavcodec/gif.c

@@ -191,6 +191,7 @@ static void gif_crop_translucent(AVCodecContext *avctx,
 
         *height = y_end + 1 - *y_start;
         *width  = x_end + 1 - *x_start;
+
         av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
                *width, *height, *x_start, *y_start, avctx->width, avctx->height);
     }
@@ -267,7 +268,7 @@ static int gif_image_write_image(AVCodecContext *avctx,
     int bcid = -1, honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette;
     const uint8_t *ptr;
 
-    if (!s->image && avctx->frame_number && is_image_translucent(avctx, buf, linesize)) {
+    if (!s->image && is_image_translucent(avctx, buf, linesize)) {
         gif_crop_translucent(avctx, buf, linesize, &width, &height, &x_start, &y_start);
         honor_transparency = 0;
         disposal = GCE_DISPOSAL_BACKGROUND;