is it perfectly viable to take mp3s encoded at higher bitrates (192 CBR) and decompress em then recompress using the -V4 --new parameters?

or is in not recommended? most of my collection is V4 so i'd like em all to conform

this process is called transcoding which involves a loss of quality. if you are able to hear that is a nother question.
generally, if don't have tight space restrictions leave the files as they are.

Also see here:

http://wiki.hydrogenaudio.org/index.php?title=Transcoding

Kristian

I recently did a little of this with some booktape files I had initially encoded with CBR at a higher than necessary bitrate. Eventually I learned about VBR and found out I could get significantly better space saving at the same transparent quality (to my ears). I was curious, so I ran some experiments on previously encoded material. I found I could save almost 50% of the storage requirement with a VBR encoding that was identical to me via WinABX. Start with one file and experiment a little.

I would not expect such dramatic results with music but I don't have an inclination to try at the moment.

You can also check this thread for a GUI front-end and perl tool that'll turn a high bitrate CBR .mp3 into a VBR .mp3.

http://www.hydrogenaudio.org/forums/index....topic=40780&hl=

Results will vary, but it squeezes some savings out of the CBR.