Less Is More: Why Audio on SoundCloud Looks Different
Last year, SoundCloud upgraded its AAC encoder for the first time in over a decade. The new one (Fraunhofer’s libfdk_aac) delivers higher perceptual audio quality across every metric we track.
But if you look at a spectrogram, you may notice something unexpected.
Here’s the scenario: you upload a lossless master. You download your track from SoundCloud and open it in a spectrum analyser. There’s a hard shelf at 17 kHz where there used to be energy all the way to 20 kHz. The old encoder kept those frequencies. The new one removes them.
It looks like a downgrade. It’s actually the opposite. Here’s why.
A lossless file (WAV, FLAC) keeps every sample intact. What goes in comes out, bit for bit. No decisions, no compromises.
Lossy compression (AAC, MP3, Ogg) is a different game. The encoder has to throw something away to hit a target file size. The question isn’t whether it loses information. It will. The question is what it chooses to lose.