Video as in true video can not be converted to audio.

Video are moving pictures as seen on a tv-screen.

We can not hear a picture no more than we can see sound/audio.

Or can we :-)

It is possible to make devices that will make it possible to listen to a video-signal.

This will however be of no actual use as our brain will not be able to utilize this sound information in any possible way I know of as to relate it back to an actual immage or moving immages.

I suppose the problem at hand is more that you have a video with sound, and you want to separate the two, keeping only the sound.

There are several solutions regarding this.

The best would probably be to use some Video-editing tool. most of these tools can separate the audio. Some are available for testingpurposes on internet. Some might even be free. Use "Google" and search for "Video Edit Software". It depends a bit on the fileformat you want to separate the audio from. Some are "protected" so that it can play audio together with video but you can not "easily" separate the two.

Nero (The full burning CD/DVD suite) might be able to do the job for you.

The "related links" down below might be just what you need too :-)

A Format 0 file (Midi 0) contains a single track and represents a single song performance. Format 1 (Midi 1) may contain any number of tracks, enabling preservation of the sequencer track structure, and also represents a single song performance. Format 2 (Midi 2) may have any number of tracks, each representing a separate song performance.

In general a MIDI file can contain 16 channels, which can each contain one or more tracks.

For instance, drums are by default recorded using channel 10.

Now you can put all drumparts on one track, but you can also make separate tracks for each drum instrument, like bassdrum, snare, hi-hat, hi-tom, lo-tom, crash, etc. This might come in handy if you want to edit the track later on.

Each of these drumtracks will be appointed to channel 10.

Now if you save this file to format midi1, all tracks will be saved separately, although they are on the same channel.

If you save the same file to format midi0 however, all tracks that are on the same channel will be merged into one single track.

Midi2 is not a fileformat, but an extension to the GM standard, and is actually called General MIDI 2.