mxg: set channel layout

libavformat/mxg.c

@@ -19,6 +19,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/channel_layout.h"
 #include "libavutil/intreadwrite.h"
 #include "libavcodec/mjpeg.h"
 #include "avformat.h"
@@ -56,6 +57,7 @@ static int mxg_read_header(AVFormatContext *s)
     audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
     audio_st->codec->codec_id = AV_CODEC_ID_PCM_ALAW;
     audio_st->codec->channels = 1;
+    audio_st->codec->channel_layout = AV_CH_LAYOUT_MONO;
     audio_st->codec->sample_rate = 8000;
     audio_st->codec->bits_per_coded_sample = 8;
     audio_st->codec->block_align = 1;