As showed on the main windows, Video to Audio Converter can do:

Extract audio from AVI, WMV, ASF, MPEG and MPG to WAV
Extract audio from AVI, WMV, ASF, MPEG and MPG to MP3
Extract audio from AVI, WMV, ASF, MPEG and MPG to WMA
Extract audio from AVI, WMV, ASF, MPEG and MPG to OGG

Tutorial:
To convert your files, please do as below:
1. Set the parameters of the format. Click "Options" on the main menu and do your settings on the "Settings" Windows. If you skip this step, Video to Audio Converter will use the settings you have used last time. If it is the first time use Video to Audio Converter, it will use the default settings.
2. If you want to convert your files to MP3, click "To MP3" button and then the conversion will begin automatically. Want to convert to WAV, to WMA, to OGG? Just do as converting to MP3.
3. Click "Stop" to terminate the conversion.

Notice:
1. To create small file, please low the parameters. But the low the parameters such as frequency and bitrate, the low the quality of your created file, though the small the file. In other words, the high the parameters, the high the quality of your created file, but the large the file.
2. To change the output directory, click "Options" and set it on the settings windows.