still super duper frustrated about the au graph..
still super duper frustrated about the au graph..
- Subject: still super duper frustrated about the au graph..
- From: "Patrick J. Collins" <email@hidden>
- Date: Fri, 20 Mar 2015 20:55:34 -0700 (PDT)
Hi everyone,
So a week or so has gone by, and I feel like I am getting nowhere (or at
least close to nowhere) with my goal of being able to simply to:
input buffer -> low pass -> new buffer
Can anyone please please please help me?
I have read pretty much all of Apple's documentation on this subject and
I just do not understand so many things...
At first I was trying to just use the default output so that I could at
least hear the low pass happening.. Unfortunately all I hear is
garbage... I figured it's because the asbd is wrong-- so I tried
setting the asbd on the lowpass unit, and I get "-10868" when trying to
set the stream format on the low pass unit's input scope or output
scope...
Then I tried to set the asbd on the output unit, and then I get error
-50, which says a parameter is wrong-- but.. the parameters are not
wrong!
AudioStreamBasicDescription asbd;
asbd.mSampleRate = 8000;
asbd.mFormatID = kAudioFormatLinearPCM;
asbd.mFormatFlags = kAudioFormatFlagIsSignedInteger;
asbd.mFramesPerPacket = 1;
asbd.mChannelsPerFrame = 1;
asbd.mBitsPerChannel = 16;
asbd.mBytesPerPacket = 2;
asbd.mBytesPerFrame = 2;
There should be absolutely nothing wrong with those parameters, so I
don't understand why it's giving a -50 error...
Regardless, I ultimately don't want to output to the hardward, I want to
do a quick offline render to lowpass filter my buffer... So, I change
my output description from kAudioUnitSubType_DefaultOutput to
kAudioUnitSubType_GenericOytput
And then suddenly my lowpass input render proc is not getting called--
which I assume is because I need to call AudioUnitRender... However, I
cannot find any documentation or examples anywhere about how to
correctly do this!
Where do you call AudioUnitRender? I assume this needs to be in a loop,
but-- clearly I don't want to manually call this in a loop myself... I
tried adding a InputProc callback to my generic output unit, but it
doesn't get called either.
Here is my code:
https://gist.github.com/patrick99e99/9221d8d7165d610fd3e1
I keep asking myself: Why is this so difficult?? Why is there so
little information out on the internet about how to do this?? All I can
find are a bunch of people asking some-what similar questions on
stackoverflow that aren't similar enough to help answer my questions.
Core audio has been around for a long time, and there are tons of apps
doing this sort of thing, so I am just really surprised by the lack of
information and available help for what seems like should be a simple
thing to do....
How about if I try this:
HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Thank you!
Patrick J. Collins
http://collinatorstudios.com
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