Extracting audio from video - opens in mono only

[RickS]

I recently downloaded Audacity 1.3.13 Beta to Windows 7 Home Premium. I also downloaded the LAME mp3 encoder and the FFmpeg import/export library. I am trying to extract the audio from a .mpg video clip. I am able to open the .mpg file in Audacity, and export to mp3 format. However the .mpg video file has stereo audio, and the audio file in Audacity and the exported mp3 audio file are in mono, left channel. When I try to import the mpg file as raw data, all I get is hissing, with a faint audio track. Any thoughts? Thanks.

[steve]

You posted in the Audacity 1.2.x part of the forum. I'll move the topic to the 1.3.x part.

How do you know that the video has stereo sound?

[RickS]

The video plays through both speakers. The audacity audio only plays through the left.

[steve]

That doesn't mean that it is stereo. If you listen to AM radio (Long wave or Medium wave) on a stereo radio, it plays through both speakers - but AM radio is mono.
I suspect what is happening is that the video file has mono audio, but when you import it you are getting a stereo track that has audio in only one channel (the left). To correct this problem you need to turn the stereo track in Audacity into a correctly formed mono track. To do that, select the track and from the Tracks menu select "Stereo Track to mono". The sound will now play through both speakers.

[DVDdoug]

Do you know anything else about the audio/video format? The audio that's multiplexed with the video can be in any format. (For example, DVDs contain MPEG-2 video and usually LPCM or Dolby AC3 audio.)

If you don't know the audio format, try checking the file with GSpot (FREE!!!) and report back.

The video plays through both speakers. The audacity audio only plays through the left.

A mono file normally plays the same audio through both speakers. When I open a mono file in Audacity, I only see one channel/waveform, and it plays out of both speakers.

The only time you should get left-only or right-only is if you have a stereo file with silence in one channel.

Here are some other FREE programs that can extract the audio from an audio/video file:
XRECODE
Pazera Free Audio Extractor
AoA Audio Extractor
SUPER

[kozikowski]

And we've been known to scramble the issue, too. To preserve space on a DVD, we sometimes create a Dolby AC3 sound track with only the first two tracks working -- stereo instead of 5.1 surround. This is format valid and supported as is sending a single sound track. AC3 is a compressed format and takes up less digital space than the linear track does.

Koz

[RickS]

I applied 'stereo track to mono' and it's now playing through both speakers.

Thanks, everyone, for your help, and for letting me know about GSpot and the other software to extract audio from video files.