Volume in Windows Vista, part 2: Types of volume in Windows Vista

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Richard Albury — Wed, 04 Apr 2007 21:20:29 GMT

I just came across this, so sorry for coming to class late. ;-)

Having been away from Windows audio for some time, is Vista audio a superset of DirectShow and DirectAudio but with a managed API?

Thanks,

Richard

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Maurits — Wed, 04 Apr 2007 22:51:25 GMT

Where does exclusive mode fit in? Does the endpoint volume apply?

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

LarryOsterman — Wed, 04 Apr 2007 23:33:26 GMT

Richard, it is essentially impossible to write a managed application that has to deal with isochronous data (without insane (1-2 seconds) worth of buffering).

Vista's new audio engine sits below DShow/DSound and is 100% UNMANAGED.

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Richard Albury — Thu, 05 Apr 2007 04:01:45 GMT

Larry, thanks for the answer. Cool: so my decade and a half of C/C++/Win32 experience still has some relevance. ;-)

Time to get a Vista machine, methinks; thanks!

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Tom M — Thu, 05 Apr 2007 11:29:58 GMT

Larry, just wanted to say Kudos for the new audio engine. It sounds great; certainly much better than the old one. It's just a shame that you can no longer get hardware acceleration of DSound, especially after I spent so much on an X-Fi. It's also a shame that the new driver architecture for display drivers has resulted in such poor performance from existing hardware that I had to switch back to XP.

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

nks — Thu, 05 Apr 2007 21:08:55 GMT

I don't really understand the difference between simple volume and channel volume. Let me see if I can get it straight:

Simple volume: Sets volume for every piece of audio playing in a program. (After their relative volumes have already been set by the stream volimes).

Channel volumes: Sets the relative volumes of all audio going to a particular speaker from a given program, regardless of source stream.

Is this correct?

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

LarryOsterman — Thu, 05 Apr 2007 21:23:37 GMT

nks: That's close enough to being right.

As I said, you can logically think of it as a two part process (since each volume is an amplitude scalar between 0 and 1, multiplying the sample by the amplitude scalar performs the desired volume scaling).

So setting the volume looks like:

foreach channel in stream

{

samples[channel] *= streamVolume[channel]

}

foreach stream in session

{

foreach channel in stream

{

samples[stream][channel] *= channelVolume[channel]

samples[stream][channel] *= simpleVolume

}

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

guoqiang lu — Wed, 11 Apr 2007 06:15:44 GMT

It doesn't work can you show all the codes public thx!

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Surge — Thu, 12 Apr 2007 15:26:38 GMT

if I understand correctly:

a session contains streams which contain channels

the channel volume controls the individual channels in a stream

the stream volume controls the individual streams in a session

the simple volume is the master volume for a session

and the endpoint volume is the master volume for a device/endpoint

what I'd like to ask (I don't have Vista yet) is:

Is there a mechanism for moving sessions between endpoints (without the apps/sessions noticing)? If not, would it be feasible? (as a powertoy for example)

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Daniel Colascione — Thu, 12 Apr 2007 17:57:10 GMT

Hey, thanks for explaining how Vista audio works; it's an area that we normally don't give much thought to, but that is actually quite subtle!

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

LarryOsterman — Thu, 12 Apr 2007 18:43:03 GMT

Surge: No there's no mechanis for moving a session between endpoints. Among the issues is that an endpoint has a particular format - the stream format may not be compatible with the format of the new endpoint.

One error in your understanding. The channel volume controls the individual channels for all the streams in the session. Otherwise you're just about spot on.

Daniel: It gets even more complicated when you consider capture.

Background on Audio Volume in Windows Vista

All the Cool Developers use Speech APIs — Wed, 18 Apr 2007 19:33:22 GMT

Our friend in the multimedia group and prolific blogger Larry Osterman is writing a series of articles

Volume in Windows Vista, part 3: Capture volume

Larry Osterman's WebLog — Tue, 08 May 2007 19:28:42 GMT

As anyone who's read this blog with any regularity knows, my son Daniel is a budding actor. As such,

re: Volume in Windows Vista, part 2: Types of volume in Windows Vista

Florencio Mazzoldi — Sat, 02 Jun 2007 01:06:41 GMT

I am building an ActiveX control that hosts a browser COM control. I would like to be able to programmatically (from my ActiveX code) control the sound volume of the embedded IE control.

I thought if I could get an IAudioClient interface from the web browser control, I could get its ISimpleAudioVolume, and that would allow me to control the sound volume. I have tried several ways to get the IAudioClient interface from the web browser control to no avail. I have even tried to get it from the IHTMLDocument. At this point, I am not sure what else to try…

Do you have any suggestions? I am on the right track for the approach? How could I obtain the IAudionClient interface from the Web Browser COM control?