avienc: saner default audio codec.

libmp3lame if available, ac3 otherwise.

libavformat/avienc.c

@@ -644,7 +644,11 @@ AVOutputFormat ff_avi_muxer = {
     .mime_type         = "video/x-msvideo",
     .extensions        = "avi",
     .priv_data_size    = sizeof(AVIContext),
-    .audio_codec       = CODEC_ID_MP2,
+#if CONFIG_LIBMP3LAME_ENCODER
+    .audio_codec       = CODEC_ID_MP3,
+#else
+    .audio_codec       = CODEC_ID_AC3,
+#endif
     .video_codec       = CODEC_ID_MPEG4,
     .write_header      = avi_write_header,
     .write_packet      = avi_write_packet,

tests/lavf-regression.sh

@@ -44,7 +44,7 @@ do_audio_only()
 }
 
 if [ -n "$do_avi" ] ; then
-do_lavf avi
+do_lavf avi "-acodec mp2"
 fi
 
 if [ -n "$do_asf" ] ; then