Re: Audio levels, without using SequenceGrabber
Re: Audio levels, without using SequenceGrabber
- Subject: Re: Audio levels, without using SequenceGrabber
- From: Jeff Moore <email@hidden>
- Date: Tue, 27 Nov 2007 18:21:33 -0800
Right. As I said, that will work fine for an engine and a process that
you have full control over. It will not work at all for metering
what's going on in another process. Nor will it help with metering
what's going on in your own process if you don't have full control
over things. For example, this won't let you meter any playback done
with NSSound.
On Nov 27, 2007, at 4:08 PM, Dave Fernandes wrote:
Perhaps I have a naive understanding of the problem, but I just
created an audio unit whose render callback computes an average
power level and stores that for readout by the UI thread.
Dave
On Nov 27, 2007, at 6:37 PM, Jeff Moore wrote:
There is no general direction I can point you at. Like I said,
there is no central point in a process where you can tap the mix.
The best you can do is deal with it on a case by case basis. For
example, our mixer AUs support metering via read-only parameters
like kMatrixMixerParam_PostAveragePower (for AUMatrixMixer). You
can use these properties in your engine to support metering.
But the same caveats I mentioned with QT apply here: this only
works for the cases you know about and have control over. Other
audio won't be included.
On Nov 27, 2007, at 3:28 PM, Neil Clayton wrote:
What would be the recommended way to monitor the current level of
an audio device?
I know if the SequenceGrabber method of doing this - but was
wondering about doing it purely in CoreAudio. I'm aware there is
no exposed API method to do it as standard, but wondered what the
general approach would be (so that I can go look in that direction).
--
Jeff Moore
Core Audio
Apple
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