Everything about File Compression: Audio Examples November 19, 2008
Posted by ConnorSmith in : Chit Chat, File Compression, Project Studio , trackbackNow that I’ve told you all about compression formats, let’s do some listening.
This article will make more sense after reading the rest of this series (Take 1, Take 2, Take 3, Take 4, Take 5, and VBR)
The following audio files were made by converting a CD quality (44.1/16) version of Steely Dan’s Hey Nineteen into compressed formats (MP3, OGG, and FLAC… still tracking down my AAC file…).
Once converted, each file was summed to mono, polarity flipped, and summed with the original WAV file.
Now – this is NOT a representation of what “MP3 takes out”. Its not that simple. These compression codecs also introduce new distortion, restructure the bit depth, time shift peaks, raise/lower noise floors, etc… Therefore, this is not all that much of a scientific comparison. So, then why are we doing it?
In essence, tests like these give you an idea of what the failure mode and distortion (aka, the “yuck”) within the compressed formats sounds like. Also, you can at least get a good idea of how the compression codec is dealing with the high end of the spectrum. Generally, the more high-end you hear in these examples, the more the codec cut out of the original file when compression down. There are 2 specific things to notice in these.
1) Compare the mp3 to the Vorbis. Notice how the Vorbis sounds more analog-like? (Much more like natural white-noise-esque analog noise, rather than the harder, digital sounding distortion of mp3) If you refer back to the article on Vorbis, you’ll remember that Vorbis alters the level of the noise floor to mask nasty-sounding distortion.
2) The FLAC summed file may not be what you expect. Remember… its lossless (!hint)
(haha, its funny to note that the following files are actually .mp3… This is a great demonstration of why we need these formats… WAV files are too big!)
256 KBPS MP3 flipped and summed with original
256 KBPS Ogg Vorbis flipped and summed with original
FLAC flipped and summed with original
Questions? Disagreements? Post it in the comments.
C
The Studio Files
Comments»
Can you make a category with the posts in them?
Yeah, great idea.
Now if you click “File Compression” in the Topic column on the right here, they should come up.
(That’s what you were asking for, right?)