Podcast Summary: Software Engineering Daily – Ableton Live with Tobias Hahn

Release Date: January 22, 2025

In this engaging episode of Software Engineering Daily, host Kevin Ball interviews Tobias (Toby) Hahn, Engineering Manager at Ableton, to delve into the intricate software engineering behind Ableton Live—a leading digital audio workstation favored by both budding musicians and industry giants like Tame Impala and Daft Punk.

Introduction to Toby Hahn and Ableton Live

Toby Hahn begins by introducing himself and his journey within Ableton. With a PhD in mathematics, Toby transitioned from academia to the practical realm of software engineering, joining Ableton right after completing his doctorate. Over the years, he has advanced through various teams and currently serves as the technical principal for Ableton Live while also managing a segment of the engineering team.

Notable Quote:

“I started as an engineer on a team that was called the Engine Team back then and made my way through various teams.” – Toby Hahn [01:25]

Understanding Ableton and Ableton Live

Ableton is both a software and hardware company catering to musicians—composers, producers, and live performers. Ableton Live stands out as a digital audio workstation (DAW) renowned for its intuitive UI combined with a robust feature set, making it accessible for bedroom producers as well as professional artists.

Notable Quote:

“We have a wide variety of users using our product.” – Toby Hahn [02:45]

Tech Stack and Legacy Code Challenges

Ableton Live's codebase reflects its 25-year history, primarily developed in C and designed for cross-platform use across Windows, macOS, and Linux (for the Push Standalone). This longevity presents unique challenges:

• Legacy Code: Toby explains the evolution of Live's code, noting the presence of custom classes and differing string encodings (UTF-16 and UTF-8) due to historical constraints.

  Notable Quote:

  “Live is mostly a C application and it is also cross platform.” – Toby Hahn [03:03]

• Maintaining and Evolving: Balancing new features with legacy constraints requires strategic refactoring. An example discussed is the View framework, initially CPU-rendered, which struggled with modern high-resolution displays. The team shifted to GPU rendering to achieve the necessary performance.

  Notable Quote:

  “We have to learn how to render stuff on the GPU.” – Toby Hahn [07:34]

UI Design and Performance Enhancements

The evolution of UI design at Ableton Live emphasizes collaboration between designers and engineers. Toby highlights the importance of maintaining performance, especially with high-resolution displays, leading to significant technical decisions like moving from CPU to GPU-based rendering.

Notable Quote:

“We try to build what they [designers] ask us to build.” – Toby Hahn [12:52]

Real-Time Audio Processing and Scheduling

A core component of Ableton Live is its real-time audio processing. Toby delves into:

• Audio Stack Constraints: Managing audio latency is crucial. The system must handle driver callbacks efficiently to prevent audio glitches, which are more noticeable than UI stutters.

• Scheduling Algorithms: Live employs a domain scheduler that breaks down audio processing into parallelizable chunks, optimizing for multi-core CPUs while managing latency introduced by certain audio effects.

  Notable Quote:

  “The audio stack obviously is a whole different beast.” – Toby Hahn [08:22]

Integration of Software and Hardware

Ableton seamlessly integrates its software with hardware controllers like Push. This integration ensures sound continuity across products, allowing users to transition effortlessly between devices and software environments.

Notable Quote:

“We try to have sound continuity here, which means reusing some of the device DSP across products.” – Toby Hahn [18:12]

Machine Learning and Ethical Considerations

While exploring machine learning, Ableton focuses on features like sound similarity search, employing neural networks to enhance user experience. Toby emphasizes ethical considerations, ensuring artists' work is respected and adequately compensated.

Notable Quote:

“There is something to navigate, what is ethical to do here and what possibilities do we have.” – Toby Hahn [31:02]

Onboarding and Engineering Practices

Onboarding new engineers at Ableton involves navigating a complex legacy codebase. Toby outlines the support systems in place, including team buddies and a culture that encourages engineers to dive into different code areas, fostering adaptability.

Notable Quote:

“We work in feature teams and a new engineer would be assigned to a feature team.” – Toby Hahn [36:28]

Testing and CI/CD Systems

Ableton has evolved its testing frameworks from early visual tests to a comprehensive suite that includes unit and acceptance tests. The transition from using Cucumber to developing their own Python-based framework, Cornichon, exemplifies their commitment to maintainable and reliable testing practices.

Notable Quote:

“We now have a big test suite. I would still say there are probably parts that are not tested or not tested enough.” – Toby Hahn [42:30]

Future Projects and Engineering Challenges

Looking ahead, Toby mentions ongoing and upcoming projects such as:

• Dependency Management: Regularly updating third-party dependencies to stay compatible with evolving platforms like macOS and Windows.
• Windows ARM Porting: Exploring the market potential and engineering challenges of supporting Windows ARM architectures, leveraging lessons learned from previous migrations like the transition to Apple Silicon.

Notable Quote:

“We have to keep up with what's going on, what's out there.” – Toby Hahn [35:43]

Team Culture and Closing Remarks

Toby underscores the significance of a supportive and collaborative team culture at Ableton, praising his colleagues' dedication and celebrating recent product milestones like Live 12 and Push releases. He emphasizes that working with great teammates makes the engineering challenges worthwhile.

Notable Quote:

“One of the things that makes it fun working here is the great team and the great colleagues that we have here.” – Toby Hahn [43:52]

Conclusion

This episode offers a deep dive into the complexities of maintaining and evolving a decades-old software product in a highly specialized domain. Toby Hahn provides valuable insights into balancing legacy code with modern requirements, fostering a collaborative engineering culture, and navigating the ethical landscape of emerging technologies like machine learning in music production. For software engineers and music technologists alike, this discussion illuminates the meticulous craftsmanship behind one of the industry's leading digital audio workstations.