[Speex-dev] Using Speex on Windows Phone 8

James Brock james.brock at 8x8.com
Thu Nov 7 15:49:39 PST 2013


I have a question regarding the viability of using Speex on the Windows
Phone 8. The constraints of my project have led me to use the Windows Audio
Session API (WASAPI) for the capturing and rendering of audio. It works
pretty dang well, except for the fact that there is no AEC unit. Hence my
use of your library. I've been able to get some pretty good echo
cancellation, but there are large discrepancies in the audio between uses
of the application. Sometimes there is no echo, sometimes there is full
echo. Sometimes the echo will fade in and out. Now, I read this on your
troubleshooting section:

"Using a different soundcard to do the capture and plaback will *not* work,
regardless of what you may think. The only exception to that is if the two
cards can be made to have their sampling clock ``locked'' on the same clock

I've also come to realize that there can be a slight clock drift between
the microphone and speakers on the Windows Phone. Does this mean what I
think it does? Will I have to find another API for audio playback/capture
or for echo cancellation? I know there are applications on the Windows
Phone that have great echo cancellation, but its frustrating that they
don't extend those APIs to the public.


*Jim Brock*
Software Engineer
james.brock at 8x8.com

8x8, Inc.
2125 O'Nel Drive
San Jose, CA 95126
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