Re: Help with monitoring system-wide audio
Re: Help with monitoring system-wide audio
- Subject: Re: Help with monitoring system-wide audio
- From: Brad Ford <email@hidden>
- Date: Mon, 26 Nov 2007 21:50:14 -0800
On Nov 26, 2007, at 7:12 PM, Bob Smith wrote:
Thanks for the pointer anyway, I didn't know about the Sequence
Grabber API and it might be useful after all. A possible brute-
force-and-ignorance solution comes to mind; externally split the
line-out audio and loop it back to the line input, then use a
Sequence Grabber to monitor audio coming to that input. Not pretty,
but quick and probably effective.
However before resorting to that, I'd like to exhaust all possible
"elegant" solutions. It would be ideal to monitor system-wide
audio, but given that the "driver tap" approach seems like it might
take more time and effort than I have available, it would probably
be good enough to just have one particular application monitor
itself. Is there an easier way to have an app monitor just it's own
audio output levels? The app in question will always be using
QuickTime (through QTKit) to generate audio, can I get anything
helpful from the QuickTime API?
Yes. You can monitor a movie's levels (the layout being played to the
output device, a stereo mix, or a mono mix), or a track's levels, or
you can even get spectral bands (for a pseudo equalizer bouncy lights
look). See QuickTime/Movies.h. Search for
SetMovieAudioVolumeMeteringEnabled and start reading.
-Brad Ford
QuickTime Engineering
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