mpeg12enc: always write closed gops for intra only outputs

Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavcodec/mpeg12enc.c

@@ -331,7 +331,7 @@ static void mpeg1_encode_sequence_header(MpegEncContext *s)
         put_bits(&s->pb, 1, 1);
         put_bits(&s->pb, 6, (uint32_t)((time_code / fps) % 60));
         put_bits(&s->pb, 6, (uint32_t)((time_code % fps)));
-        put_bits(&s->pb, 1, !!(s->avctx->flags & AV_CODEC_FLAG_CLOSED_GOP));
+        put_bits(&s->pb, 1, !!(s->avctx->flags & AV_CODEC_FLAG_CLOSED_GOP) || s->intra_only);
         put_bits(&s->pb, 1, 0);                     // broken link
     }
 }

tests/ref/lavf/mxf_d10

@@ -1,3 +1,3 @@
-8cf467a910c84dd05db24848becba42e *./tests/data/lavf/lavf.mxf_d10
+96f933913835a439dd97144303dc8929 *./tests/data/lavf/lavf.mxf_d10
 5330989 ./tests/data/lavf/lavf.mxf_d10
 ./tests/data/lavf/lavf.mxf_d10 CRC=0x4474d480