mp3 to aiff - where do all those MB come from?

[Steve Zeeeee]

Premiere Pro would not read some MP3 files.  Someone said to

convert them to aiff, which did work.  But the file size multiplies

by ~TEN !   What happens when that happens?  I can only imagine

dust and air being introduced in all the spaces between the old and

new megabytes, like in a photo over enlarged to dust and air.

[SteveG_AudioMasters_]

.aiff is an uncompressed format - MP3 is heavily compressed. So really, it's the other way around; all the detail in the original before it was compressed to MP3 has gone, and if you decode an MP3 and store the result as .aiff then yes, you won't benefit audibly from the conversion. MP3 is a reduced-quality distribution format which was never intended to be used for production purposes - if you convert it to .aiff or wav, then what you are doing is making a very detailed record of all of the MP3's defects! If you decode an MP3 to work on it, and then save the results as another MP3 then it gets even worse, as there's another loss each time you re-encode it.

[Steve Zeeeee]

Why wont Premiere Pro read some of these?
Is there another option to cconvert that is more sensible

than TEN times file size, so premier Pro can use these sounds, pleasE?

Thanks !

[SteveG_AudioMasters_]

When an MP3 file is encoded, there's what is called a 'coding gain', and this is basically the amount that a file is shrunk by, in file size. It follows that when it's expanded again, it will return to nominally the same size it was before compression. Short of saving it in a reduced specification wave file (which will make it sound even worse) there's no way around this - it's dictated by the Laws of Physics!

As for why Premiere Pro won't read MP3s, I don't know. I suspect that it behaves the same way that Audition does, and won't tolerate files in a session that are not in the session format. And that format has to be an uncompressed wav file as far as the audio's concerned. What it does is strip the audio from the video, which lets you manipulate it separately, but that stripped audio is uncompressed - it has to be, otherwise the 'edit in Audition' option wouldn't work. Audition on its own decodes MP3 files before inserting them into a session, and uses the decoded version, not touching the original at all.