mplayer doesn't play audio on some DVB recordings

[jfaulkne@…]

I use mythtv to record over-the-air ATSC broadcasts. I have a script which compresses these recordings to xvid using mencoder. I noticed that there is no audio on some of these compressed recordings. This does not seem to have to do with the actual content of the ATSC broadcast, since one night's mencoded evening news will have audio, and the next night's evening news won't. So this does not seem to be an issue with codecs, it may be a minor imperfection in the recording that causes this.

However, xine can play these raw DVB recordings with audio just fine. mplayer cannot, so the problem probably exists in the mplayer audio decoding engine. I have tested this with mplayer 1.0rc1, gentoo's mplayer build, and an SVN build which I checked out last week, and all versions exhibit this problem.

I have 2 example raw DVB recordings which mplayer cannot play the audio on, but xine can. These recordings are very large, they are hour long recordings weighing in at 6.7 gigabytes each. I know this is alot to download, but I have put them on an extremely high bandwidth site, so the download speed will probably be limited by your internet connection. Anyway, here they are, again 6.7 gigs each:
​http://128.36.236.149/mplayerbug/1081_20070910180000.mpg
​http://128.36.236.149/mplayerbug/1081_20070918190000.mpg

I've also created files with the first 20 megabytes of each file. If you'd rather not download the above files, hopefully these will be sufficient. Again, they are 20 megabytes each:
​http://128.36.236.149/mplayerbug/small-1081_20070910180000.mpg
​http://128.36.236.149/mplayerbug/small-1081_20070918190000.mpg

Both mplayer and mencoder fail to output any audio with these recordings, while xine outputs audio just fine for the entire duration. I also have some sample mencoder output for the 1081_20070910180000.mpg recording. Here is the SVN version of mencoder's output when used in verbose mode on this file, the size of the text output is 47 megabytes:
​http://128.36.236.149/mplayerbug/svn.mencoder.output
and here is the encoded file (320 megabytes):
​http://128.36.236.149/mplayerbug/svn-test.avi

Please let me know if you'd like any more information.

[reimar]

There is no bug, the files contain two audio streams, one of which contains silence.
Select the one containing the proper audio by either giving -aid 52 (mplayer -identify | grep ID_AUDIO_ID is useful to find all audio streams) or switch during playback via '#'.
-demuxer lavf "fixes" it as well as it by pure luck selects the non-silent one by default.