Contant Peak, Constant RMS, How to get a fixed value for peak and RMS Options

[terataz]

Hi, we are trying to set a default standard for the volume of the audio files we are working on.
We are looking for a tool that, given a bunch of mp3 files, will be able to normalize them at a given db.

For example : 0db for Peak levels and -9db for RMS.

Ideally, we'd love to use sox as we can chain it with other effects we're using without the need to convert multiple time the file from mp3 to wav and back.

We tried sox gain -n , sox gain -ne, sox gain -nb, sox loudness but none of them keep a constant RMS without varying the Peak level as well.
Any help appreciated.
Thanks

[AndyH-ha]

Peak and RMS are not tied to one another. Making them so would probably lead to some peculiar results -- not that modern mastering doesn't often produce rather peculiar results. I don't use things like ReplayGain, so I could be quite wrong, but I did not think such tools applied compression, which is a rather more complicated process than adjusting either peak or RMS. The results you aim for will require a multi-band compressor, at the least, or an RMS adjustor plus a ruthlessly used hard limiter.

On the other hand, from the comments I've seen is this forum and other places, most modern pop, rock, and other such genres that one finds widely played on radio, etc. frequently has well less than 9dB total dynamic range to begin with, let alone 9dB between RMS and peak. Of course if you are recording your own material, or getting 50 year old stuff from LP, that is a different matter.