Upmixing and the Future of In-Car Audio 

User experience innovations popularized by electric vehicles are raising buyer expectations with features such as semi-autonomous driving, rapid charging, quieter cabins and enhanced in-vehicle mobile connectivity delivering greater user satisfaction. Those heightened expectations, combined with the trend of EV drivers spending time in the cabin while charging, have increased customer interest in high-quality audio technologies that deliver immersive music through the use of DSPs with advanced algorithms.

As home audio systems have added new processing capabilities and compatibility with leading surround sound and immersive audio protocols, customers have become accustomed to enjoying lifelike reproductions of virtually any recorded music at home. This new consumer standard makes it obvious when a vehicle delivers comparatively low-quality audio, causing automotive customers to feel left behind.

With a majority of music content now delivered via streaming services, publishers, producers and content creators can easily offer multiple different channel mixes to satisfy various immersive audio standards. However, these content owners are unlikely to remix most of the hundreds of millions of existing two-channel recordings, opening the door for a technological solution to improve immersive qualities and match the surround sound listening experience provided by modern standards. 

Following the upward trends in buyer expectations and technical audio capabilities, audio system designers are increasingly looking to high-quality surround sound upmixing to provide immersive audio experiences from any source through algorithmic channel spatialization that doesn’t require human adjustment.

What is Surround Sound Upmixing?

Surround sound upmixing is an advanced software feature of digital signal processors (DSPs) that digitally restructures a song’s channel separation in real time, achieving truly immersive multi-channel experiences regardless of the input source, musical style or original mix characteristics. The technology analyzes source content and splits the signal into component parts based on spatial attributes. 

The upmixing technology then arranges the component parts into any number of distinct output channels, generating a multichannel version of the same content and distributing it to multichannel-capable sound systems without requiring a surround sound processor. All of this happens as a song is playing.

While some legacy upmixing solutions are known to alter a track’s spectral composition and require re-tuning of connected audio systems and filters, the latest surround sound upmixing technologies employ new algorithms to minimize such effects and deliver accurate, natural, immersive playback from any input. Automotive OEMs hoping to attract discerning customers can ensure consistent premium audio experiences across a wide range of vehicles by implementing new upmixing solutions with faster, simpler setup processes that produce superior results and involve minimal stereo system re-tuning.

Surround sound upmixing can be applied to any audio signal and does not require creators or publishers to reformat or remix existing content to achieve optimal performance from various stereo designs and channel configurations. As a result, upmixing allows listeners to reinvigorate their entire music catalogs and libraries with enhanced quality and separation. Serving as a supplement to leading modern audio protocols such as Dolby Atmos, upmixing ensures an immersive listening experience for every song. 

What Makes Surround Sound Upmixing an Optimal Solution?

Immersive audio has taken the audio industry by storm in recent years, with brands as big as Apple now marketing their headphones based on audio spatialization and the ‘real-life’ listening experience it delivers. To provide equivalent quality in vehicles, OEMs require highly flexible solutions that can adapt to a range of speaker system architectures, from entry-level two-channel systems to ultra-premium systems with height speakers and subwoofers. 

Upmixing is the optimal solution for immersive in-car audio because it automatically works with all input sources and can be custom-tuned to maximize the effectiveness of any vehicle’s speakers and stereo system. Some vehicles can be upgraded easily, such as models already using Dirac’s Intelligent Audio Platform, which offers numerous patented algorithms to tune and adjust sound characteristics. For these vehicles, audio engineers can simply add our new upmixing module to the signal path without other modifications.

Not All Solutions Are Created Equal

In general, consumers are more likely to bypass or ignore a new technology if it trades one form of quality for another or suffers from performance issues. If an upmixer exhibits strange amplitude modulation, poor transient response or any other audio degradations, audio engineers can struggle to produce satisfactory results. Low-quality upmixers can also require laborious and expensive tuning processes for each vehicle model. The latest surround sound upmixing solutions resolve both of these issues, offering much faster implementation and tuning for entire vehicle lineups thanks to the elimination of audio defects.

Competing platforms may also offer different levels of sophistication, such as the maximum number of output channels. Automotive OEMs require upmixing solutions that are highly configurable and flexible, so the same technology can be applied across all vehicles to deliver every customer a premium experience.

Automakers also want users to have control over their experience, with various immersive options such as an “on the stage” mode or an “in the audience” mode that alter channel separation to provide distinct spatial characteristics. These types of end-user adjustments are only possible through newer, more powerful upmixers that eliminate artifacts automatically in real-time.

The options and capabilities of a solution are reliant on how much power the DSP provides, affecting the number of virtual channels, availability of presets and number of speakers that can be connected.

Vehicles of the Future

While the long-promised revolution of self-driving vehicles has yet to be fully realized, the concept itself introduces major opportunities for changes in how commuters spend their time in a vehicle. Large digital displays are already becoming commonplace, and in a self-driving vehicle, it’s natural to think that users may shift toward video content, with the car’s stereo functioning as a surround sound system.

A high-quality upmixing solution can turn virtually any audio source into an immersive soundscape, which is even more crucial when the listener’s attention is fully focused and not split between operating the vehicle and enjoying the audio.

As vehicles continue to advance, so will the demand for premium in-car entertainment experiences, and we are hard at work leveraging Dirac’s scalable technology to deliver a product roadmap with upmixing solutions for every class of vehicle.

It’s All About the Experience

Automakers and their audio engineers are gaining new tools to improve the in-car audio experience, and upmixing is currently the only technology that can intelligently re-mix existing audio signals in real time. Finally, automakers can deliver a luxury audio experience without needing artists to personally remaster tracks for each different stereo.

With high-quality upmixing like that offered by Dirac’s solution, automakers can optimize every song to deliver premium audio in virtually any vehicle, allowing users to elevate their existing music libraries and hear them in a whole new way.

By Emil Hemström and Rüdiger Fleischer, Dirac