Audio Extraction question

[Keithchr]

I see everywhere comments about converting audio from wav to pcm etc and the need to extract it to do this. My question is why is this necessary? What does it do? Do you have to do it?

Hat off to the guys in the know.

[redwudz]

WAV files are very large and if you encode a video with them they take up quite a bit of space which can be better used for increasing the bitrate and quality of the final video. The extraction is just to seperate the audio and video streams that are normally combined in a video file. If you have a small video file you may not need to do this, as long as it will fit on your media. You might download AVIcodec or Gspot. They will show you the sizes of the audio/video files and what type of encoding they have.

[Keithchr]

Thanks for quick reply -beginning to understand now. Do all Avi's Mpeg1 files have wav sound initially then?

[redwudz]

The most common is MPEG-1 Layer2 and AC3 audio. WAV is similar to what a music CD uses. There's a lot more to it, though. You might look at the 'What is' column under VCD, SVCD and DVD to see the commonly used audio formats. Also the 'Glossary' for a short defintion of the terms used.