Painless high-performance audio on iOS and Mac OS X

Am I crazy? Has this always been the case and nobody noticed until now? Novocaine is outputting audio in mono through headphones. ioData->mBuffers[0].mNumberChannels is 1.

If I figure out why, I'll make a note, and, with luck and a good attitude, commit some code.

Hi there, First of all let me thank you for open sourcing this. It looks like a very valuable tool coming from somebody who has suffered from CoreAudio coding.

I've been checking out your library to see how robust it is in regards to backgrounding and interuptions etc.

I've found a crashing bug that initially makes me think it isn't that robust but maybe you can comment on it.

Testing on iPad 3 with iOS 5.1. Simple app that launches a recording queue with: audioManager = [Novocaine audioManager]; //This starts an input Block for recording. Set to audioManager.inputBlock=nil to stop audioManager.inputBlock = ^(float *data, UInt32 numFrames, UInt32 numChannels) { NSLog(@"stillgoing:%d",(int)numFrames); };

I tried going in and out of background and that appears to work fine (for short term at least).

But if I send the app to background, then start playing audio from the stock Music app, then go back to the app running Novocaine I get this error in the console: Error: Checking number of input channels ('!cat')

If you repeatedly take your headphones in and out really fast, the sound that is playing either becomes out of sync in the left and right headphones (usually), or the sound becomes extremely choppy (sometimes).

I noticed that you do a lot of stuff when the audio route changes so I commented that part out and it ended up fixing both symptoms of the issue for me. I'm going to investigate further.

What fixes it:

• Commenting out [sm checkSessionProperties]

What doesn't fix it:

• Dispatching [sm checkSessionProperties] to another queue (WEIRD!)
• Commenting out all of the NSLogs
• Commenting out the CheckErrors
• Commenting out [self checkAudioSource] in checkSessionProperties

SO I think the problem is all of the calls to AudioSessionGetProperty when the audioRoute changes. What I think you should ACTUALLY do is have custom getters for numInputChannels, numOutputChannels, etc. And when the audio route changes, set all of them to -1. When the getter is called, and if they are set to -1, THEN it calls AudioSessionGetProperty.

edit: Nevermind, I tried implementing the above and it didn't fix the problem. I'm stumped.

I have difficulty when I include the novocaine into my project. I get the Unknown type name 'class' error. If i have Novocaine as a project as downloaded from the Github - I am able to get it running. Any help?

When I tried to incorporate novocaine into my own project I get a lot of tricky warnings and link errors. It's kind of neat how you've integrated C++ and Obj-C++ into a minimal number of source files, but I wonder if you're confusing the compiler/linker

1. I get warnings which I frankly do not understand surrounding the blocks. ("Capturing 'self' ...")

2. Probably related: I get warnings about these declarations:

It wants me to use copy instead of retain.

I assume that my project settings are wrong in some subtle way (I've tried to match them to yours) — but I want to understand what's going on since I need to integrate this stuff into a much larger project.

The guide says "All you have to do is put your audio into "audioToPlay". What would be the appropriate way to do it? I have a NSData with the audio.

Thank you very much!

@alexbw I want to get your eyes on this, I've been using it for my own projects but I want to make sure I didn't miss anything and that this is a direction you're comfortable with.

I tested all the demos on both iOS and OSX and they all seem to work, but you know the project much better than I do, so it's entirely possible that I missed something.

If you'd prefer to keep this in its own branch for awhile that is also fine.

The primary changes are as follows

Code Style and Fixes

• Uses ARC right out of the box
• Removal of all ivars that were backing properties, in favor of auto-synthesized properties (much cleaner, works on XCode 4.4+)
• Moved several properties/methods to class continuation in source file to make them "private"
  • Several things that don't need public access
• Several other properties made readonly in public interface to prevent fiddling (for things that users should never set)
• Block setters/getters explicitly declared so that auto-complete will fill in the arguments for you
• Replaced deprecated AudioProperty getters for OSX (enumerating devices, etc)

Functional Changes

• Ability to route output to speaker on iPhone (boolean flag)
• Must explicitly call "play" to hear audio
  • I wasn't sure if you'd go for this one or not. It will definitely have an impact but it makes pre-initialization config options possible, since before it would automatically play the first time you access the singleton.

TODO

• Ability to disable input processing entirely (commented out right now, not implemented yet)
  • Requiring manual call to "play" allows configuring this prior to starting AU
• More advanced audio session/routing capabilities
  • Choosing output routes, etc
  • LOTS of things are available in newer OS versions, for example, audio routing to external devices, etc

Thanks!

Hi, could you explain how to change current sample rate?

Lines inputFormat.mSampleRate = 44100.0; outputFormat.mSampleRate = 44100.0;

dont affect to this

thanks

Ok so when I just add the Novocaine folder with all the library files and I build it gives me automatic reference counting errors. What build settings should I be using?

Hi

When I uncomment the filewrite example code in the demo view controller, on the first run everything is fine, but on the second run,

CheckError(ExtAudioFileCreateWithURL(audioFileRef, kAudioFileM4AType, &outputFileDesc, NULL, 0, &_outputFile), "Creating file");

exits the app with error code -48, which is declared in MacErrors.h as duplicate filename.

I will try to find a work around this and post it here.

best

Hi, First off I would like to say great work and thank you for contributing this open source project, it is much appreciated by many of us.

I'm having a little trouble adding this to my iOS project, and actually i'm not quite sure if this is the best solution for me so I thought I would ask you since you seem to know a good bit about audio.

I am designing an application for kids that allows them to play along with certain songs/stories. I dont need to do any complicated audio processing, all the sounds are going to be pre recorded samples in specific keys. The only manipulation to the audio that I'll need is that I'll need to play up to 6 different audio clips at the same time and I will need to be able to adjust the levels of each audio track.

I tried adding your code to my project but I am having trouble with dependencies... and the whole .mm thing. If you could include a short guide on the easiest way to add this to an existing project it would be greatly appreciated.

Hi there;

I'm working on porting an iOS libpd project to Mac using Mac Catalyst, and I'm currently looking for a CoreAudio wrapper to process input/output samples in libpd from an Audio Unit. I was referred to this project by the main libpd dev; and while I was able to get Novocaine's sample projects to work, the project exits on launch in my Mac Catalyst project after calling [Novocaine audioManager].

Here's the error I receive:

 [as] AudioSessionClientImpl.mm:232:-[AudioSessionClientImpl AudioSessionGetPropertyImpl:size:data:]: Error: AudioSession not initialized
Error: Couldn't check the audio route ('!ini')

CoreAudio seems to be pretty tricky on the Catalyst platform because its not really the Mac platform, and not really iOS. If you had any suggestions for possible workarounds please let me know — otherwise I'll keep researching ✌️

For iOS a sampling rate of 44,100 Hz is hardcoded. For newer iOS devices the sampling rate is 48,000 Hz. This causes a crash on setup. Sampling rate is for iOS already determined from the Hardware.

Hi , is there any way to set audio sample rate to 8000hz or 16000hz and i want to get all array as short array.

[audioManager setInputBlock:^(float *newAudio, UInt32 numSamples, UInt32 numChannels)

And whats the float range ? is it returning between [-1,1] ? I need in short like this: [audioManager setInputBlock:^(short *newAudio, UInt32 numSamples, UInt32 numChannels)

Sorry if this a stupid question. Just wondering if anyone could shred a light on this... I've imported all Novocaine files to my project and renamed the files that will use Novocaine to .mm Just this error on RingBuffer.h refuses to go away during compiling:

RingBuffer.h:31:1: Unknown type name 'class'; did you mean 'Class'? Parse Issue: RingBuffer.h:31:17: Expected ';' after top level declarator

Is it anything I could be missing, like a compiler setting or a flag option somewhere else? I'm using Xcode 8.33 and iOS deployment target 10. Thanks in advance.