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[Please read this whole description before commenting in order to make sure you haven't misinterpreted my intentions for this video. The purpose of this video is to demonstrate a technique that you can use on your own, it's not meant to compare MP3 to a lossless format.] This is a method compare the difference between a lossless file and a compressed version of that file. This isn't just limited to MP3s - any audio compression that doesn't speed up, slow down or change the volume in audio can be tested with this technique provided that you have the original, uncompressed version that was used to create the compressed version. What this does is cancel out everything except for the differences in the two files by inverting one and mixing them after they're both lined up. Anything that's not present or has been added during compression can be heard. I used Adobe Audition to do this, but Audacity works as well. I used a slightly sped-up version of the song “The Bad Touch“ because it was easy to line up the lossless and lossy versions, and it has both high and low frequencies. The lossy version of the file was encoded at 192Kbps using Adobe Audition . Additionally, I normalized the mixed track in order to allow it to be heard better. But the purpose of this video is a tutorial so you can do this yourself and experiment more, allowing you to hear it at its original volume or whatever your heart desires. Addendum: YouTube does use compression so this isn't a fair comparison, but is more intended as a demonstration of a technique you can try on your own. Still, just for fun, I did try comparing the two after YouTube compressed the video's audio. Here's the original audio's spectrograph as encoded by YouTube : And the MP3 version, again as YouTube encoded it: And you can compare those to how it looks in the video. Obviously the high frequencies are cut off and there is some clipping that was introduced apparently, but there are still noticeable differences between the two. Probably not audible differences, though. Just in case anyone is wondering, to get the video's audio to make those images, I used a service that downloads the direct audio stream from YouTube to an M4A file (no re-compression, just the straight audio data from YouTube ), then used NeroAAC to decode that into a .wav file. No transcoding used, let alone transcoding to MP3.
