h263: disable loop filter with lowres

Fixes ticket1212
Found-by: Piotr Bandurski <ami_stuff@o2.pl>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/intelh263dec.c

@@ -77,7 +77,7 @@ int ff_intel_h263_decode_picture_header(MpegEncContext *s)
         }
         if(get_bits(&s->gb, 2))
             av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
-        s->loop_filter = get_bits1(&s->gb);
+        s->loop_filter = get_bits1(&s->gb) * !s->avctx->lowres;
         if(get_bits1(&s->gb))
             av_log(s->avctx, AV_LOG_ERROR, "Bad value for reserved field\n");
         if(get_bits1(&s->gb))

libavcodec/ituh263dec.c

@@ -963,6 +963,8 @@ int ff_h263_decode_picture_header(MpegEncContext *s)
             s->h263_aic = get_bits1(&s->gb); /* Advanced Intra Coding (AIC) */
             s->loop_filter= get_bits1(&s->gb);
             s->unrestricted_mv = s->umvplus || s->obmc || s->loop_filter;
+            if(s->avctx->lowres)
+                s->loop_filter = 0;
 
             s->h263_slice_structured= get_bits1(&s->gb);
             if (get_bits1(&s->gb) != 0) {