"V" For Vista
A new Microsoft OS is a big deal. But this time, it's a big deal for pro audio.
The wraps are finally coming off Vista. While there's been a lot of buzz about the look, the graphics, and the seemingly never-ending product introduction delays, a quiet audio revolution has been happening behind the scenes in Redmond. And as we get closer to the day when Vista actually hits the shelves, it's becoming transparently clear - like the "Aero" look itself - that Vista, the next-generation Windows operating system, takes pro audio very seriously. Windows is installed in about 95% of all client computers, and it's been awhile since Microsoft introduced a new operating system. Part of that is because, frankly, Windows XP really got it right. It seemed light years ahead of Windows 98, and thanks to widespread support and excellent stability, there was no great clamor to change it. Yet Windows Vista represents the most important element in Microsoft's upcoming product roster; it's expected to sell upwards of 100 million copies in 2007. With those kinds of expectations, Vista couldn't just be an incremental upgrade - it had to set phasers on stun, and wow the target audience. Luckily for us, Microsoft considers pro audio a vital part of that target audience.
Overhauling The Windows Audio Infrastructure
The audio in earlier versions of Windows has never quite worked the way pro audio software developers wanted, and was getting unwieldy and difficult to modify. So, Microsoft rebuilt Vista's underlying audio architecture to provide greater performance, stability, and audio fidelity; the company is even hopeful Vista will spark a new round of evolution in music technology. Microsoft has now made it easier for developers to write programs by simplifying the way software interfaces with the underlying hardware. There's a lot more going on under the hood, like revised driver structures, enhanced API sets that provide application isolation (one badly behaving audio app can't bring down the system), incorporation of reusable components to reduce the need for custom components, and optimization to prevent memory fragmentation and manage large memory requests. There's also an emphasis on improved audio quality. In rewriting the audio stack, an entire new audio subsystem evolved called User Mode Audio (UMA), with developers using a new set of interfaces known as WASAPI (Windows Audio Session API). Windows Vista uses 32-bit floating point calculations by default in the core of the audio system to provide higher-quality digital signal processing, bit-for-bit sample level accuracy, and up to 144dB of dynamic range. And the new audio WaveRT (Wave Real Time) architecture allows for much lower hardware latency in audio apps. Developers will certainly have a much better underlying audio system as a foundation. But will your current apps work? Most likely. Although completely overhauled, Microsoft wanted to make sure there was backward compatibility in Windows Vista. Current music apps and drivers should work fine, except some may not when you venture into 64-bit systems - we'll cover more on this later. Like the audio infrastructure, the MIDI engine has also been rebuilt to minimize system wide impact, but you won't see any new MIDI features just yet. Nonetheless the underlying work has primed the platform for changes, and presumably, Windows Vista follow-up releases will take advantage of this.
Microsoft rebuilt Vista's underlying audio architecture to provide greater performance, stability, and audio fidelity; the company is even hopeful Vista will spark a new round of evolution in music technology.
Glitch Resistance
The entire OS has a priority structure, where a new operating system feature (Multimedia Class Scheduler Service) can prioritize audio apps over other processes to provide glitch-resilient operation. Under current versions of Windows, a wi-fi alert, instant message, antivirus program or some other process could steal processing power from the application and cause an audio glitch; so it was necessary to disable various programs to make sure they did not interrupt. But despite best efforts to disable potential threats, Windows is a busy system and there are processes always going on - networking, drive scanning, caching, etc. Sometimes priority gets confused and if every process has the same priority there can be a bottleneck or, even worse, a crash. Microsoft endeavored to make the audio in Windows Vista as glitch-resilient as possible by allowing apps to prioritize audio over all other application processes using MMCSS. Once applications start to utilize this new feature, you will be able to run your audio in Windows Vista without having to go in and disable various processes. At the Microsoft Audio Summit held last year, Arif Gursel (Program Manager on the Microsoft WAVE team) ran a massive stress test demonstration - the equivalent of running dozens of apps simultaneously to try to break the system. The audio processing and playback was prioritized over other apps, video, mouse movements, screen redraws, etc. and no matter how hard he tried to stress the system, the audio kept playing seamlessly. I was pretty impressed.
Per App Volume Control
Figure 1
In the previous versions of Windows, volume was universal across all apps so some sounds might blast you while others were barely audible. Not only that, but each new app might change the settings on the system and alter the sound. This got so confusing that some audio devices shipped with their own control panels, and disabled the system device controls. With Vista, the Per App Volume control feature provides separate volume slider controls for each application that plays audio, thus giving the option to differentiate and control what's piped through the audio engine (Figure 1).
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Author
Gary Garritan
Gary Garritan is an award-winning soundware developer. His sample libraries have won accolades from celebrity musicians and music press alike, and been used in a variety of applications: from popular TV shows, film and attractions to video games, live concerts and ballets. Many schools and universities have chosen Garritan Libraries for use with their music programs.