Lets say you have a 96 kbit mp3 and you [Transcode](https://en.wikipedia.org/wiki/Transcode) the file into a 320 kbit mp3. How could you programmatically detect the original bit rate or quality? [Generation loss](https://en.wikipedia.org/wiki/Generation_loss) is created because each time a lossy algorithm is applied new information will be deemed "unnecessary" and is discarded. How could an algorithm use this property to detect the transcoding of audio. 

128 kbps LAME mp3 transcoded to 320 kbps LAME mp3 (I Feel You, Depeche Mode) 10.8 MB.  

[![alt text](https://i.stack.imgur.com/ICIqm.png)](https://i.stack.imgur.com/ICIqm.png)

This image was taken from the bottom of [this site](https://web.archive.org/web/20141015214328/http://blowfish.be:80/eac/Spectral/spectral.html). The 2 tracks above look nearly identical, but the difference is enough to support this argument.