Re: Streaming Graph to file without a sound
Re: Streaming Graph to file without a sound
- Subject: Re: Streaming Graph to file without a sound
- From: Brian Whitman <email@hidden>
- Date: Mon, 19 Jun 2006 13:56:32 -0400
If you install XCode2.3 the PlaySequence version there has a "export
to file" option. The basics of it are
1) swap your output unit with a generic output unit
2) tell all the AUs in the graph to go offline,
3) have a render callback on something right before the output unit
with the writeAsync stuff in it,
4) call AudioUnitRender on the generic output unit.
There is some strange bug/feature associated with
kAudioUnitRenderAction_OutputIsSilence in the rendering that
segfaults if you don't check for it, I never got around to really
testing it out.
If you still need help come back and ask-- this is something I am
intimately familiar with :)
-B
--
http://variogr.am/
On Jun 19, 2006, at 1:47 PM, Craig Hopson wrote:
I understand that I can use ExtAudioFileWriteAsync (etc.) to create
a file and stream the output of my graph to it. Here's the
twist... I don't want to hear the output while I'm writing the
file. So, this is more like Export to file. My graph currently
consists of custom generator unit(s), connected to a matrix mixer,
connected to the default output unit. I need the graph to generate
the output because I rely on event timing from the MusicSequence
and the graph drives this nicely.
I suppose for my export I could spoof the output unit by filling
its buffers with zeros while writing the actual data to file. This
seems a bit much. Am I missing something simple? Should I switch
to AUHAL rather than the default unit for the export? Is there
support in AUHAL for this that I've missed?
Thanks for any help.
Craig Hopson
Red Rock Software
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