Amplifying MP3 files and file size reduction

Hello All,
I am new to audacity. I wanted to know how to use the effect “amplify” without reducing the file size. It seems each time that I export a file that I have amplified, the end result is a smaller file size than the original file. The amplification effect seems to work fine, but audacity reduces the file size. How can I stop the reduction of the file size when it is amplified? Also, if I amplify a file, shouldn’t the file size increase rather than decrease? Thanks so much for your help on this.

Best,
Andrevoce

File size is determined by the bitrate (kbps = kilo_bits_ per second) and playing time. If you know there are 8 bits in a byte and you know the bitrate you can calculate file size.

Audacity (and any “normal” audio editor) has to decompress the file before editing and when you re-save (export) it gets re-encoded to whatever settings/bitrate you choose. (If you choose VBR = Variable Bit Rate, you choose a quality setting and LAME uses the required moment-to-moment bitrate as required by the particular program material.)

It’s best to avoid multiple generations of lossy compression (as you may know, MP3 is lossy compression) if possible. You may not hear any quality loss from re-compressing (especially if you use the same or higher bitrate) and there are times you can’t avoid it, but it’s something you should be aware of.

If all you are doing is changing the volume, [u]MP3DirectCut[/u] can do that (and some other limited editing) without decoding/re-encoding. That makes it faster and there’s no quality loss.

Thanks, DVDdoug, for your reply. I will certainly follow your expert advice.

Best,
Andrevoce