Backstage Blog

• Audio
• Engineering
• Transcodings
• Streaming

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…

• API
• Announcement
• Transcodings
• Streaming

We’re introducing an important change that will affect how you stream tracks!

• Web
• Playback
• TypeScript
• Streaming

Maestro is a library we have developed to handle all playback across SoundCloud web applications. It successfully handles tens of millions of plays per day across soundcloud.com, our mobile site, our widget, Chromecast, and our Xbox application. We are considering open sourcing it, and this blog post is a technical overview of what we’ve achieved thus far with Maestro.