How do you use Vegas to read the source file properties?
You can’t but there is a great free utility called GSpot that can. It will not only tell you what codec you need but it will also tell you if it’s installed on your PC.
Do you need to pre-convert this file for Vegas to see the audio? And if so, is there good freeware for this?
Yes, quite often you need to convert files from whatever format a particular camera shoots into a format that is easier to edit. Some free utilities to do this are AviDemux, MPEG Slipstream, and Super(c).
It is important to point out that Vegas expects to see certain audio codecs with certain video codecs so while these programs will allow you to mux any type of video and audio together, it may not be a combination that Vegas can support. I would stick with PCM audio which is almost always supported and is also the highest quality.
~jr
http://www.johnrofrano.com
http://www.vasst.com