Enable avpicture_deinterlace() for PIX_FMT_GRAY8.

Patch by Andrea Gualano, gualano T imavis O com

Originally committed as revision 10712 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/imgconvert.c

@@ -2824,7 +2824,8 @@ int avpicture_deinterlace(AVPicture *dst, const AVPicture *src,
     if (pix_fmt != PIX_FMT_YUV420P &&
         pix_fmt != PIX_FMT_YUV422P &&
         pix_fmt != PIX_FMT_YUV444P &&
-        pix_fmt != PIX_FMT_YUV411P)
+        pix_fmt != PIX_FMT_YUV411P &&
+        pix_fmt != PIX_FMT_GRAY8)
         return -1;
     if ((width & 3) != 0 || (height & 3) != 0)
         return -1;
@@ -2845,6 +2846,9 @@ int avpicture_deinterlace(AVPicture *dst, const AVPicture *src,
             default:
                 break;
             }
+            if (pix_fmt == PIX_FMT_GRAY8) {
+                break;
+            }
         }
         if (src == dst) {
             deinterlace_bottom_field_inplace(dst->data[i], dst->linesize[i],