Errr... so when our customers call to ask us, "Why is the Windows Vista OS audio engine mucking about with audio bits when not necessary?", we should tell them, "global warming"? Somehow, I don't think that'd fly on our FAQ. ;-)
The problem is that, from the user's point of view (and from the application's point of view), the OS audio engine is NOT predictable. When the user configures their application to open their audio device to play or record audio at rate X, and some other rate Y is chosen, that is not predictable behavior.
Now, you can make the argument that this actually is predictable behavior because the user should have known rate Y would be chosen -- after all, it's the user's control panel where rate Y was selected. And if all users were perfect, and always knew about all the controls panels that are buried 3-levels deep, and always remembered what they set them to last week, maybe that would be a consideration.
As it stands, all the user knows is that they told their application to do X, and Windows Vista forced it to do Y instead, with no warning, no ability to override it, no ability to detect the change until it's too late, and oftentimes no ability to recover from it, since audio recording is a "one shot" experience.
We probably do have some end-user customers who don't know or care about Windows Vista monkeying with their audio. But every single one of our large customers DOES care. And, without exception, NONE of them plan to migrate to Windows Vista because the audio engine policies make that platform unusable for their applications. Some of them are even considering moving to another OS that is ... well ... humane to audio.
Is there any chance a "Use application settings" option could be added to the Sound control panel? When enabled, it would override the sample rate/bit depth settings in the control panel and cause all requests to open the device to be at the application-specified sample rate and bit depth; any request to open a device that was already open at a different rate/depth would be denied. If a control panel option isn't viable, what about a shim that does the same thing? Or a control panel option or a shim that makes all the "legacy" audio APIs work in exclusive mode?
I think that would resolve the problem for all of our customers who currently can't use Windows Vista. And since absolutely no sample rate conversion would ever take place, it would be a "greener" solution, too.
Best regards, -Dan -- Dan Germann Digital Audio Labs ----- Original Message -----
From: Hakon Strande <hakons@xxxxxxxxxxxxxxxxxxxxx> Date: Sun, 7 Dec 2008 18:30:16 -0800 Subject: [wdmaudiodev] Re: Vista Sample Rate Changes"Apparently by design in Vista, only the user can set the hardware sampling rate" Assuming this thread is about programmatic control of Windows Sound Control Panel settings:Features requested by this very community in the past; the need for a transparent, predictable OS audio engine avoiding the OS audio engine mucking about with audio bits when not necessary lead to a Vista audio system design where the user is in control because:1. Devices don't know what content the user is playing, only what that particular device/endpoint is best at rendering2. Applications certainly should not muck around with settings that affect other applications because an application does not know what other apps using that device is rendering.Better to leave it to the user or at the default setting.Also, in Vista the default device sample rate (if the device supports it) is 44.1kHz because 95% of content is still mastered at that rate and it is the rate that offers the least amount of quality impact and CPU processing impact for the largest number of audio scenarios.We did a rough calculation of how many trees we would save by not sample rate from 44.1kHz to for instance 48kHz (common sample rate used by devices) for let's say 250 million PCs (about the number sold in a year) by users using the PC to play music (a common scenario for approx. 60% of us) and while I can't find the numbers right now it amounted to A LOT of trees.So, think green and don't muck about with audio sample rate settings programmatically :).Sincerely,Hakon Strande<mailto:HakonS@xxxxxxxxxxxxx> | Software PM | Microsoft Hardware
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