Re: Output Capture
Re: Output Capture
- Subject: Re: Output Capture
- From: email@hidden
- Date: Wed, 18 Jul 2007 13:29:51 -0600
On Jul 18, 2007, at 1:04 PM, Jeff Moore wrote:
The output buffers are there for _you_ to put data in. Until you do
that, the buffers will be filled with zeroes.
The system does not provide any means for accessing the output data
going to the device.
OK I found this post just after I sent my email, which puts a damper
on things:
http://lists.apple.com/archives/coreaudio-api/2006/Jan/msg00101.html
All is not lost though. What would also work for me is, if I could
pipe the output of the sound manager into an audio unit or something
that mixes it, and then have 1 single output, that I could use as an
input for echo cancellation, and then could pass on to the output
device. I found this:
http://developer.apple.com/qa/qa2005/qa1394.html
Which kinda sorta suggests that there is a way to find things like
NSSound or the Carbon Sound Manager as an input. This may not be
doable though, for the same reason we can't capture the mac's whole
output.
The trouble is that I have 2 carbon sound callbacks in my app, one
for voice, and one for our game sound fx, and I can't mix those
easily (for one thing their sample rates and number of channels are
different, and for another, the code is leftover from OS 9 days and
pretty complicated to dive into). But I COULD pipe these into core
audio in a thread safe way from the 2 callbacks, and get 1 output. I
just have no idea how to do this. I've read over the core audio
manual pdf, it's just a lot to take in. So while the concepts are
fairly simple, I don't feel ready to just start typing code, and was
hoping for an example.
P.S. I think that since capturing output is disabled for DRM, then a
built-in echo cancelled sound input is a requirement. This would be
extremely easy for apple to do, since they are already doing it in
iChat I believe. Also, this needs to be included in a system update
retroactively for 10.3.9, or as a small lib we can include in our
app's package, so that we can use it in games.
Well, thanx for your help,
--Zack
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