Well, the size of the file is correct. FYI, here's how it goes:
44.1kSamples/sec x2 (it's stereo) = 88.2kSamples. Each sample is 32 bits, so that's 88.2 x 32 = 2822.4 bits/second. Divide this by 8 gives you 352 KBytes per second. Multiply this by 60 gives you 21.168MBytes per minute. Multiply that by your 15 minutes gives you 317.52Mbytes for your file size - so you've gone around 15 or so seconds over 15 minutes! In a nutshell, the more bits, the bigger the file - and it's directly proportional to the number of them.
But I'm still not clear - are you editing this bounced-down file (I still don't see why you need that, incidentally) in Waveform or Multitrack? It would be perfectly possible to do most, if not all of that, in multitrack view using the automation system. But what exactly are you doing with the file once you've created it? This file, in it's unedited form, is effectively your new master, and that's the one you should be keeping at least two copies of, and editing only one of them. So initially do a Save, and a Save as, in another location, and don't touch it. If you open up the copy of this file in Waveform view, nothing actually gets altered, whatever you do, until you re-save the file. Until that point, it's stored in a series of temp file locations. Each time you make an edit, it's stored again - the whole thing. If you do a load of edits before saving, then the temp file will become enormous. And, with a big file, it's perfectly possible to run out of temp file space and crash the file... so, if anything at all goes wrong, then yes, I could see the file saving the previous (incorrect) temp location, which would certainly give you a file that's appeared to revert.
And it's that, with large files, that would incline me very much to do as much of that editing in Multitrack view as possible, as you'd only need to be saving changes to the session file - much less likely to have space problems.
AdChoices