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Why Vista sounds worse
Posted Date: 03 Feb 2008
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Posted By: Baljeet Member Level: Diamond
Rating:  Points: 5
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Changes to how the latest version of Windows handles audio playback has caused unexpected quality issues for musicians and consumers alike----
Just what does a glitch sound like? That's easy, explains Steve Ball: "Glitches during music playback can sound like a loud 'pop' or like a brief slice of silence where your music should have been." As the senior program manager for sound in Windows Vista, Ball knows that nobody wants that.
So it must have been difficult for him to author a blog post explaining why Vista suffers from precisely that problem - glitches on some systems during music playback or composition.
Boiled down, his explanation is: because Windows has to do lots of things at once. His best news? "Windows developers have made significant progress in reducing glitching. For example, music playback on an otherwise lightly loaded system can be generally as smooth as [a] $20 (£10) CD player."
But that's hardly what someone using a £1,000 computer wants to hear. Among the scores of comments, one remarked: "My mobile phone can play MP3s, while I surf the web, on a call and text message; all without any glitches."
So what's gone wrong? Our investigation suggests a combination of wholesale changes to the way Vista handles audio, late bugfixes, and problems in drivers written by the makers of soundcards.
For music professionals, though, it's a dealbreaker. Will Benger, a musician who also works at Making Waves Audio, a music technology retailer, advises his customers to stick with XP. "Vista is riddled with issues with existing software packages and existing hardware," he says. "If you've got problems with recording audio, you might not get a second chance. You can't sell a system to a professional studio if you don't know for sure that it's going to work."
That's a problem in the professional music market, where Apple has a significant share - one-third or more - of the market. Apple went through similar struggles with musicians in the shift to OSX; but that was more than five years ago. Now it's Microsoft's turn.
No cakewalk
Not everyone has problems with audio in Vista, but it is still perplexing. How could Microsoft set out to improve the audio system, yet end up making it worse?
Noel Borthwick, chief technology officer for Cakewalk, which creates music software for both the consumer and professional markets, recalls his company's first involvement with Vista - in 2003. "Microsoft had a Vista audio summit - it was called Longhorn at the time - and invited several vendors for private meetings to put forward the specification for audio in Vista and try and collect feedback."
Fundamental changes were on the way: many of Cakewalk's products used a programming interface called DirectSound, which was being phased out. "We went back and re-invented all the stuff that we did in our applications," Borthwick says.
In 2005 there was another conference. "Microsoft presented Vista as it was going to be released. We found some fundamental flaws. WaveRT [see panel] is a new mechanism by which audio drivers would perform really well. There were a couple of flaws in the design. We pointed out the flaws before Vista shipped."
Microsoft made changes - but they came so late in Vista's development that a number of companies released drivers for WaveRT used the old, inefficient model. "So there's a fundamental flaw right there for consumer audio," Borthwick says.
In fact, Vista's new audio setup lays numerous traps for driver authors. Most off-the-shelf PCs have integrated soundcards, produced by companies such as Realtek and Analog Devices, makers of SoundMAX. Borthwick says these tended to have older WaveRT drivers.
Users of add-on sound cards such as those from Creative Labs suffered different problems: those drivers often required an emulation system to work in Vista, a sure recipe for poor performance.
"The end-user experience on consumer audio devices is pretty bad on Vista for the most part," says Borthwick.
Professional musicians face different issues. For performance reasons, professional audio drivers tend to bypass the Windows audio engine, using de facto standards such as Steinberg's ASIO (Audio Stream Input/Output).
"Nothing really changes in how you talk to an ASIO driver in Vista as compared to XP," Borthwick says. "The problem under Vista is overhead in the operating system itself. It takes more CPU to achieve the same result. You tend to get clicks or pops or noise."
Things can only get ...
Vista's audio is getting better. Drivers are improving, and the imminent Service Pack 1 apparently fixes some bugs, such as one that affected timing on MIDI (used by professionals to integrate sequencers).
Experts agree that Vista's audio has potential. "The WaveRT driver architecture can produce better performance," says Robin Vincent of Rain Computers, which builds PCs for musicians. "However, no one supports that. That's the problem."
Steinberg's Lars Baumann believes Vista will improve. "We think Vista is going to be the future platform for audio applications, but it will take more time."
Another promising area is 64-bit computing. "A 64-bit operating system breaks down a lot of the barriers to RAM and performance. It just seems to be really hard to move people to it," Vincent says.
"Vista still has promise," Borthwick says. "Microsoft needs to clean up the loose ends in Vista to make it deliver. I still think it's possible."
Different key: how audio changed in Vista
Larry Osterman, a Microsoft software design engineer, says there were three goals for audio in Vista. First: improve system stability. Windows is designed round a low-level component called the kernel. If software within the kernel crashes, all of Windows crashes. By contrast, processes running outside the kernel can be safely killed and restarted. Microsoft moved most audio processing, apart from the audio driver itself, out of the kernel.
The second goal: improve audio quality by reducing processing delays (called latency), critical for professional users. The third goal: a better user interface for controlling audio.
Latency indicates how long it takes for an audio event - a beep, a chunk of music from an MP3 file, a MIDI signal - to travel through the system. It is critical for professional audio, which typically has several devices and channels that must be kept tightly synchronised.
To achieve these goals in Vista, Microsoft created a new audio engine. Data flows through a stack of software components. Audio processing components handle digital effects and volume, a mixer component combines the sounds when several sources are playing at once, and a streaming component in the kernel feeds the sound to the audio driver. The low-level interface to the new engine is called WASAPI, the Windows Audio Session Application Programming Interface.
Microsoft also introduced a new type of low-level audio driver, WaveRT (Wave Real Time). This is the preferred driver type for Vista. A WaveRT driver passes audio to the hardware with low latency and minimal interference.
But late in Vista's development cycle, Microsoft added an optional event-driven mode for WaveRT drivers, so audio applications do not have to query the driver repeatedly. Unfortunately many audio hardware vendors have not yet supplied WaveRT drivers for their products. Another weakness of WaveRT is that it only works with internal sound devices, not external devices connected by USB or Firewire. Some professional audio drivers bypass the built-in audio engine, using Steinberg's ASIO or a technique called Kernel Streaming.
Finally, Vista has a scheduler service, which allows applications to register for prioritised use of system resources.
Realising that users would want to use their old software and hardware, Microsoft maintained compatibility as far as it could. Older audio standards still work, but are emulated by software that feeds into WASAPI.
In the case of DirectSound, that is unfortunate, as it was designed to enable low-level access to sound hardware - but no longer does so. Further, the new WaveRT drivers are not a requirement for Vista; older driver types are also supported, even though they work less well. All can lead to glitches
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