Sometimes there's just no other way to go about it: you have to rip some audio from a video. it may be a rare piece of music, or a specific version of a song you like, or a dialogue you want to add to a remix. But to do such a thing, you have to jump through a lot of technical hoops. To make the process easier, software like Xilisoft's Video to Audio Converter exists.
The program is essentially a very simple audio extractor. It lets you select a video file of a supported format, those include AVI, MPEG, WMV, DivX, MP4, H.264/MPEG-4 AVC, RM, MOV and some others. Then the built-in interface helps you choose a part of the file or the entire audio track from it and start the procedure of extracting the audio. It converts the track to MP3, WMA, WAV, RA, M4A, AAC, AC3, OGG or Sun AU. The conversion itself is fast and adjusts itself according to your hardware specifications. It supports multi-core CPU in order to optimize conversion.
Output audio files are fully customizable. You can select several formats at once to create different file copies, edit ID3 tags, precisely edit the time of the start in the track from video and the time of its end, specify the size of an output file, split a single file into several, choose audio quality, channel, sample rate and a lot of other minor or secondary parameters.
Xilisoft Video to Audio Converter supports several languages and various skins to make it visually pleasing, can run as a background application, supports batch conversion and does everything to be one of the most comfortable converters in existence. It costs some money, if you want full functionality, but it's definitely worth it.