Re: iChat's echo cancellation (was Re: Output Capture)
Re: iChat's echo cancellation (was Re: Output Capture)
- Subject: Re: iChat's echo cancellation (was Re: Output Capture)
- From: Matthew Xavier Mora <email@hidden>
- Date: Thu, 19 Jul 2007 08:50:06 -0700
At 7:21 PM -0400 7/18/07, Andrew Kimpton wrote:
rary, obviously there won't be any sample code for that. But that
aside, there is all sorts of sample code for all the APIs that
iChat uses out of Core Audio.
Some folk here seem (from my reading of the messages) to want access
to the audio emitted by the computer itself in order to eliminate it
from captured audio as part of an echo cancellation process ? They
seem to be strengthening the argument by suggesting that iChat does
the same thing ?
I'm assuming iChat's algorithm does not cancel out all audio coming
out of the computer, only the audio it receives from the other end.
(the computer could be playing music via itunes and the other end may
want to hear that) Since it is highly likely that the audio coming in
from the network will be played out the speakers and thus reappear on
the input signal, you can make the assumption that they would keep
that audio around as a hint of what will likely need to be canceled a
few milliseconds from now. What they do need is a good latency
estimator, then they can estimate how long to wait before the audio
they just played is likely to come back in again.
Matt
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