avformat/mpegts: set correct extradata size for Opus streams

map_type 0 is always 19 bytes, whereas map_type 1 and 255 are 21 + channel
count bytes.

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/mpegts.c

@@ -2031,6 +2031,7 @@ int ff_parse_mpeg2_descriptor(AVFormatContext *fc, AVStream *st, int stream_type
                     st->codecpar->extradata[19] = opus_stream_cnt[channel_config_code];
                     st->codecpar->extradata[20] = opus_coupled_stream_cnt[channel_config_code];
                     memcpy(&st->codecpar->extradata[21], opus_channel_map[channels - 1], channels);
+                    st->codecpar->extradata_size = st->codecpar->extradata[18] ? 21 + channels : 19;
                 } else {
                     avpriv_request_sample(fc, "Opus in MPEG-TS - channel_config_code > 0x8");
                 }

tests/ref/fate/ts-opus-demux

@@ -1,4 +1,4 @@
-#extradata 0:       30, 0x69290482
+#extradata 0:       29, 0x64a70482
 #tb 0: 1/90000
 #media_type 0: audio
 #codec_id 0: opus