Re: Help with monitoring system-wide audio
Re: Help with monitoring system-wide audio
- Subject: Re: Help with monitoring system-wide audio
- From: Bob Smith <email@hidden>
- Date: Mon, 26 Nov 2007 19:12:34 -0800
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?
(A quick overview of the project, in case it helps. This is a multi-
media kiosk display system consisting of a player app plus "helper"
apps to play QuickTime files. The helpers run as separate processes
to prevent QuickTime instabilities and memory leaks from messing with
the player. The player can also be operated via a remote-control app
from another computer, where the kiosk itself is not visible, so I
need a status display showing video and audio are actually being sent
to the kiosk. Ideally I want the player to directly sample what is
going to the hardware, partly because the actual playback is done by
separate applications, but also to allow a remote operator to detect
any possible glitch, i.e. the screen-saver being activated. This is
easy to do with video by just grabbing directly from the Core
Graphics frame buffer. I'd like to do something similar with audio;
but if that isn't feasible I could live with having a helper app
monitor it's own audio and report the result to the player.)
Again, many thanks for any help you can provide.
Bob S.
On Nov 26, 2007, at 2:40 PM, Jaime Magiera wrote:
On Nov 26, 2007, at 5:38 PM, Jeff Moore wrote:
This would let you monitor the levels of incoming audio. But the
question was about monitoring the levels of audio coming out of
other application. The QT Sequence Grabber isn't going to help you
with that.
Ahhh yes, I see that now, thanks.
JLM
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