[wdmaudiodev] Re: Audio device control in Windows 7.

  • From: mana <m92.suzuki@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 29 Sep 2009 11:37:15 +0900

Hello.

Thank you for your response.

Michail Nikolaev  wrote:
> Also, in Windows Vista and Windows7 you can use loopback recording to
> capture audio output via user mode. See Core Audio API documentation(for
> AUDCLNT_STREAMFLAGS_LOOPBACK param).

I was using the loopback recording to capture audio.
But I changed the way to do that to using virtual driver, because
there were some problems.

For example:
  - When an actual rendering device is not connected, it is not
possible to record.
  - When the default device is S/PDIF, DTS and AC3 cannot record.
  - When my APP send the captured audio data to a client terminal, I
want to block
    the sound output from the rendering device off completely without
mute control from APP.
  - etc.

On the other hand, there is one problem in the recording by the
virtual sound driver.
That's the problem that there is no way to change the default audio
device from my APP.

As the next step, I am investigating audio redirection of the RDP.
If audio redirection of RDP matches to my application, I will try
using this mechanism.

Thanks & best regards,
Mana.

> Hello.
> Also, in Windows Vista and Windows7 you can use loopback recording to
> capture audio output via user mode. See Core Audio API documentation(for
> AUDCLNT_STREAMFLAGS_LOOPBACK param).
> 2009/9/28 mana <m92.suzuki@xxxxxxxxx>
>>
>> Hi all,
>>
>> I am developing the sound capture application in Windows 7.
>> My goal is ...
>>
>>  1.Capture mixed audio output on the system using my virtual sound driver.
>>  2.Without changing the preferred audio device by the user.
>>  3.Captured audio data will put to the own audio encoder and send to the
>> client
>>    process which runs on remote and local PC.
>>
>> Now, my problem is No.2.
>> And I know that there is no public mechanism (APIs) to change the default
>> audio device from my application.
>>
>> Then, I have two question.
>>
>> Q1.
>>  I want to disable all physical audio devices and enable only my
>>  sound device (my virtual sound driver). Is it possible?
>>  I want to do the state like the "Remote Playback Audio" that
>>  appears in the audio redirection of RDP session.
>>
>> Q2.
>>  In a server PC, Can I establish the RDP session only of audio?
>>  I want to use only the audio redirection of the RDP. If it is possible,
>>  I think that I will capture audio system data from "Playback audio
>> device".
>>
>> Q3.
>>  Is there any information about the mechanism of RDP audio redirection?
>>
>>  I am studying now about the RDP (Service APIs/Vitual
>> Channel/Protocol ...) at the MSDN Library,
>>  but I am still insufficient of understanding.
>>
>> Thanks & best regards,
>> Mana.
>> ******************
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