Music fanatics and DJs claiming to only (illegally) download music files in the highest quality possible can now put their money where their mouth is. Because the open source tool ‘Spek’ allows you to run a spectrum analysis on every music file type, to see the true quality of the file.
Let’s face it, most of our iTunes library consists of mp3s, as the they’re still considered to be the most convenient type of music file. But it’s also the lowest form of digital music, which sacrifices quality for size. For example WAV or FLAC (lossless audio) files benefits the listening experience much, much more. Still, whether the purists like it or not, mp3 has been the dominant file type ever since we bought our first iPods.
Within the mp3 spectrum, however, there is a lot of difference in quality to be found as well, with 128kbps (lowest) and 320kbps (highest) bit rates being the two border values. In general, both are lossy compressed versions of the original wave form. Kilo bits per second is basically a measure for quality. You can compare it to a the compression of a picture using the JPEG file format. The lower the quality, the smaller the files size and the more ‘blocky’ the picture becomes.
“The bitrate/audio quality that shows up in your iTunes or download website doesn’t always tell the truth”
Downloading mp3’s for free, ripping from YouTube or SoundCloud or even an official promo from a record label (as we have encountered ourselves) can never guarantee 320kbps in an mp3 file, even though it says so on your iTunes or other media player.
To check the true quality of an audio file is to run a spectrum analysis. A spectrum analysis is nothing new, what it does is measure the power and magnitude of an input signal versus frequency. From this you can tell whether your music files reaches all the frequencies that were designated in the original recording of a piece of music. There are many programs that can run a spectrum analysis, but the one that’s most easy to use is probably Spek, a piece of free, open source software where you just drag your audio file into and see the results in a Volume vs. Hertz graph.
Here are a couple of examples that can act as a guideline when testing your audio files:
When the high frequencies are cut to about 20khz, that means you’re dealing with a 320kbps mp3 audio file
High frequencies cut to 16khz equal to a bit rate of around 192kbps
The same goes for this spectrum, although there is also a significant loss of volume visible here
High frequencies cut to 12khz tells you that the audio file has a bit rate of no more than 128, the lowest possible bit rate for an mp3 music file
This is the spectrum of a FLAC (lossless audio) file. Here you can see that the high frequencies go well beyond 22khz, proving it to be a music file of pristine quality
So, whether you’re a DJ – you’d be amazed at how many DJs are not yet familiar with spectrum analysis and just take it for granted that the tracks they play in clubs are all 320kbps or higher – or an avid music listener, software like Spek can be a nifty little contribution to the state of your digital music collection. Check it out and be surprised of how much of your music you thought was topnotch scores much lower in audio quality.
