On Wed, Dec 24, 2014 at 1:14 PM, Murthy Gandikota <[email protected]> wrote:
> To correct myself, it has nothing to do with hardware. I am using > ast_openstream acquire the stream object. I then use ast_write to send a > frame on the stream to all the conference members. Meanwhile another > thread is waiting for events on the channel (ast_waitfor) and if a spoken > frame is sensed, then it is being queued for the conference members. Here > is the catch: if I do ast_write(stream, NULL) and speak up on the phone, > then I can hear an echo of myself. So it must be possible to do > ast_write(stream, frame) and hear an echo, if the talk volume is > sufficiently higher than the listen volume? > > > I have no idea what App Konference is doing with the media mixing that it is performing. ast_write and ast_waitfor have nothing to do with the act of mixing media however - those are merely calls to write media to a channel and to wait for a file descriptor on a channel to be triggered. That actual act of mixing the media would have to be provided by something else. In bridge_softmix - which is a bridging module for the Bridging Framework that mixes media between n channels - we explicitly remove the source channel from the media that is mixed for it - so you don't hear yourself. But that's an implementation detail of that mixer - other mixers could choose to echo back the audio from the speakers. Volume, again, is handled by something else completely different from mixing media. In the case of func_volume, an audiohook is used to manipulate the media prior to it being written down into the channel technology. The audiohook itself is invoked via ast_write. -- Matthew Jordan Digium, Inc. | Engineering Manager 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA Check us out at: http://digium.com & http://asterisk.org
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