Wednesday, December 10, 2008 10:30 AM
Maurits
Sample - playing silence via WASAPI event-driven (pull) mode
Be vewy vewy quiet - we'we hunting wabbits.
-- Elmer Fudd
Attached is a mini-app I've written to play silence to any given playback device using WASAPI event-driven (pull) mode. Source, x86 binary, and amd64 binary are attached.
Usage statement:
>silence -?
silence
silence -?
silence --list-devices
silence --device "Device long name"
With no arguments, plays silence to the default audio device.
-? prints this message.
--list-devices displays the long names of all active playback devices.
--device plays silence to the specified device.
>silence --list-devices
Active render endpoints found: 2
Speakers (USB Audio Device)
Headphones (High Definition Audio Device)
>silence --device "Headphones (High Definition Audio Device)"
Press Enter to quit...
Received stop event after 488 passes
While it's playing it shows up in the Volume Mixer:
Why would I write such a thing?
Well, there is the pedagogical exercise of writing a WASAPI event-driven render loop.
But there is also a practical application of an active silence stream, having to do with loopback capture. More on this in a future post...
EDIT: 7/30/2009 - fixed bug where I was treating the GetCurrentPadding value as the amount of free space in the buffer when in fact it's the amount of used space.
While I was at it, added an icon and exited immediately on errors rather than waiting for the caller to hit Enter.
