mdec: set color_range

libavcodec/mdec.c

@@ -219,6 +219,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
     if (avctx->idct_algo == FF_IDCT_AUTO)
         avctx->idct_algo = FF_IDCT_SIMPLE;
     avctx->pix_fmt  = AV_PIX_FMT_YUVJ420P;
+    avctx->color_range = AVCOL_RANGE_JPEG;
 
     return 0;
 }