Backstage Blog

• Android
• Mobile
• Playback
• Media

Media and playback are at the core of SoundCloud’s experience. For that reason, we have established and grown an engineering team that is specialized in providing the best possible streaming experience to our users across multiple platforms.

To do this, we combine the industry’s best-fitting solutions with our own custom technologies, libraries, and tools. In this article, let’s dive into how we improved latency in our Android application by leveraging a new engine for our player’s audio sink.

• Monitoring
• Prometheus
• SRE

If there is anything like a silver bullet for creating meaningful and actionable alerts with a high signal-to-noise ratio, it is alerting based on service-level objectives (SLOs). Fulfilling a well-defined SLO is the very definition of meeting your users’ expectations. Conversely, a certain level of service errors is OK as long as you stay within the SLO — in other words, if the SLO grants you an error budget. Burning through this error budget too quickly is the ultimate signal that some rectifying action is needed. The faster the budget is burned, the more urgent it is that engineers get involved.

This post describes how we implemented this concept at SoundCloud, enabling us to fulfill our SLOs without flooding our engineers on call with an unsustainable amount of pages.

• 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.

• Announcements
• Security

We’re excited to announce the launch of our public bug bounty program with Bugcrowd — the #1 crowdsourced security platform. This public program is open to Bugcrowd’s full crowd of top, trusted whitehat hackers, and we will award up to $1,500 per vulnerability identified on our website, API, and mobile apps.

• Android
• Mobile
• Release
• Testing
• Engineering

Once every two weeks, we prepare new versions of our mobile apps to be published to the app stores. Being confident about releasing software at that scale — with as many features and code contributions as we have and while targeting a wide range of devices like we do at SoundCloud — is no easy task. So, over the last few years, we have introduced many tools and practices in our release process to aid us.

In this blog post, I’ll cover some of the techniques we use to guarantee we’re always releasing quality Android applications at SoundCloud.

• Search
• Performance
• Engineering

In the past, the Search Team at SoundCloud had high lead times for making updates to Elasticsearch clusters, either during the implementation of a new feature or simply while fixing a bug. This was because both tasks require us to reindex our catalog from scratch, which means reindexing more than 720 million users, tracks, playlists, and albums. Altogether, this process took up to one week, though there was even one scenario where it almost took one month to roll out a bug fix.

In this post, I would like to share the concrete Elasticsearch tweaks we made so that we can now reindex our entire catalog in one hour.

• Engineering

Last month we launched SoundCloud Premier Distribution, which allows creators to distribute their music from SoundCloud to other streaming platforms and stores. For many of our users, this will be their first experience with the conventions and requirements of the music industry supply chain. Due to strict requirements regarding metadata and media, the barriers to entry to this world are very different than those to a creator uploading to SoundCloud. The aim of SoundCloud Premier Distribution is to make the path from SoundCloud upload to off-platform plays as frictionless as possible. Here we’ll look at how a system of automatic and manual validations allows users to get fast feedback as they prepare a release.

• Engineering
• Engineering Culture
• Engineering Management

Although it can be easy to know if you’ve messed up badly as a manager, it’s not always as easy to know if you’re doing a good job. In particular, the power dynamics at play can make it hard for people on your team to feel confident letting you know what’s working well and what’s working not so well. In this article, I’m going to talk about an approach I started using in the last few years that seems to strike the best balance of getting the input managers need while still promoting a healthy culture of direct feedback.

• Engineering
• JavaScript
• Redux
• React

This post describes why and how we implemented a garbage collector in our Xbox application on top of Redux and in addition to the JavaScript engine’s regular garbage collector.

• Engineering Culture
• Tech Debt

Almost every company accumulates tech debt as time goes on. Tight deadlines, changing requirements, scaling issues, poor or short-sighted system designs, knowledge silos, inconsistent coding practices, turnover of key staff — these things all happen and can contribute to tech debt. So what can be done about it once it’s there?