Is your UIViewController not working correctly? Maybe viewDidLoad is being called, but nothing else seems to be? Check your view controller in Interface Builder, check the connections – is your view connected? Disconnect it and link it manually in your loadView method. Now your other methods will magically be called correctly. No idea why this is.
I’ve just spend the better part of an afternoon & evening trying to figure this out, so thought I’d share it….
I’m trying to make the synth behave nicely on the iphone by having it auto rotate when the screen rotates. The code I have works very well in the simulator, but shows screen corruption after the rotation. If you then rotate back, it displays well again. So it seems my resize code maybe isn’t up to snuff.
According to this post on Red Glasses (this link’s down now, apparently it was a draft version up for a select few to read, but google got there early), it may be related to CALayer/UIView resizing. Looking at the behaviour, this seems likely.
Anyway, here’s the before & after. Any suggestions?
One more post for Valentine’s day. I quite like the disco floor colours of this one. The Synth needs a distinct look. (Never mind a distinct name!)
Synth 14/2/2010
Here’s a grab of the latest version of Synth. Not much has been going on at a superficial level, but quite a bit has changed under the hood:
So whats next?
There would still be loads to do after that (e.g., loading and saving compositions), but for a 1.0, maybe even a released version, I think I’d need most of the above.
I previously stated that I had a fix for the AudioOutputUnitStart -66681 error, then updated the post stating I’d failed.
Today, Sijo asked if I had any idea about how to fix the problem. Unfortunately I don’t…. But I haven’t had that error for a long time, so I figured I might as well post my audio setup code here (along with the callbacks). Hopefully it’s a useful comparison. It works, and is reasonably documented (IMO). It’s not my exact code, it’s a couple of classes copied & pasted, so it’ll have to be adapted somewhat. Let me know if there are any problems.
First, the AudioSourceInterface. Implement this to provide the audio samples.
#pragma once
#include <Coreaudio/CoreAudioTypes.h> // All this for SInt16....
class AudioSourceInterface
{
public:
virtual void audioRequestedFloat(float* output, int numSamples, int numChannels) = 0;
virtual void audioRequestedInt(SInt16* output, int numSamples, int numChannels) = 0;
};
Now the AudioEngine base class. First the header, which is later subclassed for the iphone implementation.
#pragma once
#include <AudioUnit/AudioUnit.h>
class AudioSourceInterface;
class AudioEngine
{
public:
AudioEngine();
virtual ~AudioEngine() {}
void setup(AudioSourceInterface* audioSource);
void exit();
protected:
AudioUnit mAudioUnit;
AudioSourceInterface* mAudioSource;
float mSampleRate;
virtual void createAudioUnit() = 0;
virtual void enableAudioUnit() {}
void setupAudioUnit();
void setupIntAudioStream(AudioStreamBasicDescription* audioFormat) const;
void setupFloatAudioStream(AudioStreamBasicDescription* audioFormat) const;
static OSStatus floatRenderer(void* inRefCon,
AudioUnitRenderActionFlags* ioActionFlags,
const AudioTimeStamp* inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList* ioData);
static OSStatus intRenderer(void* inRefCon,
AudioUnitRenderActionFlags* ioActionFlags,
const AudioTimeStamp* inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList* ioData);
};
And the AudioEngine cpp body…
#include "AudioEngine.h"
#include <AudioUnit/AudioUnit.h>
#include <AudioUnit/AudioComponent.h>
#include "AudioSourceInterface.h"
#include "Core.h"
AudioEngine::AudioEngine():
mSampleRate(kSampleRate)
{
}
void AudioEngine::setup(AudioSourceInterface* audioSource)
{
mAudioSource = audioSource;
createAudioUnit();
enableAudioUnit();
setupAudioUnit();
}
void AudioEngine::setupAudioUnit()
{
// We tell the Output Unit what format we're going to supply data to it
// this is necessary if you're providing data through an input callback
// AND you want the DefaultOutputUnit to do any format conversions
// necessary from your format to the device's format.
AudioStreamBasicDescription audioFormat;
setupIntAudioStream(&audioFormat);
OSStatus err = AudioUnitSetProperty(mAudioUnit, kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Input, 0, &audioFormat, sizeof(audioFormat));
assert(err == noErr);
// Initialize unit
err = AudioUnitInitialize(mAudioUnit);
assert(err == noErr);
// Set render callback
AURenderCallbackStruct input;
input.inputProc = intRenderer;
input.inputProcRefCon = this;
err = AudioUnitSetProperty(mAudioUnit, kAudioUnitProperty_SetRenderCallback,
kAudioUnitScope_Input, 0, &input, sizeof(input));
assert(err == noErr);
// Start the rendering
// The DefaultOutputUnit will do any format conversions to the format of the default device
err = AudioOutputUnitStart(mAudioUnit);
assert(err == noErr);
// we call the CFRunLoopRunInMode to service any notifications that the audio
// system has to deal with
CFRunLoopRunInMode(kCFRunLoopDefaultMode, 2, false);
}
void AudioEngine::exit()
{
OSStatus err = AudioOutputUnitStop(mAudioUnit);
assert(err == noErr);
err = AudioUnitUninitialize(mAudioUnit);
assert(err == noErr);
err = AudioComponentInstanceDispose(mAudioUnit);
assert(err == noErr);
}
void AudioEngine::setupIntAudioStream(AudioStreamBasicDescription* audioFormat) const
{
memset(audioFormat, 0, sizeof(audioFormat));
audioFormat->mSampleRate = mSampleRate;
audioFormat->mFormatID = kAudioFormatLinearPCM;
audioFormat->mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
audioFormat->mFramesPerPacket = 1;
audioFormat->mChannelsPerFrame = 1;
audioFormat->mBitsPerChannel = 16;
audioFormat->mBytesPerPacket = 2;
audioFormat->mBytesPerFrame = 2;
}
void AudioEngine::setupFloatAudioStream(AudioStreamBasicDescription* audioFormat) const
{
memset(audioFormat, 0, sizeof(audioFormat));
audioFormat->mSampleRate = mSampleRate;
audioFormat->mFormatID = kAudioFormatLinearPCM;
audioFormat->mFormatFlags = kAudioFormatFlagIsFloat | kLinearPCMFormatFlagIsNonInterleaved;
audioFormat->mFramesPerPacket = 1;
audioFormat->mChannelsPerFrame = 2;
audioFormat->mBitsPerChannel = 32;
audioFormat->mBytesPerPacket = 4;
audioFormat->mBytesPerFrame = 4;
}
OSStatus AudioEngine::floatRenderer(void* inRefCon,
AudioUnitRenderActionFlags* ioActionFlags,
const AudioTimeStamp* inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList* ioData)
{
assert(inNumberFrames <= kAudioBufferSizeFloats);
AudioEngine* self = (AudioEngine*)inRefCon;
float* buffer = static_cast<float*>(ioData->mBuffers[0].mData);
uint bufferSize = ioData->mBuffers[0].mDataByteSize;
// Get synth sound data for one channel
self->mAudioSource->audioRequestedFloat(buffer, inNumberFrames, 1);
// Duplicate single channel across all channels
for (UInt32 channel = 1; channel < ioData->mNumberBuffers; channel++)
memcpy (ioData->mBuffers[channel].mData, buffer, bufferSize);
return noErr;
}
OSStatus AudioEngine::intRenderer(void* inRefCon,
AudioUnitRenderActionFlags* ioActionFlags,
const AudioTimeStamp* inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList* ioData)
{
assert(inNumberFrames <= kAudioBufferSizeFloats);
AudioEngine* self = (AudioEngine*)inRefCon;
SInt16* buffer = static_cast<sint16*>(ioData->mBuffers[0].mData);
// Get synth sound data for one channel
self->mAudioSource->audioRequestedInt(buffer, inNumberFrames, 1);
// Duplicate single channel across all channels
uint bufferSize = ioData->mBuffers[0].mDataByteSize;
for (UInt32 channel = 1; channel < ioData->mNumberBuffers; channel++)
memcpy (ioData->mBuffers[channel].mData, buffer, bufferSize);
return noErr;
}
The AudioEngineIPhoneImpl header.
#pragma once
#include "AudioEngine.h"
class AudioEngineIPhoneImpl: public AudioEngine
{
protected:
void enableAudioUnit();
void createAudioUnit();
};
And the AudioEngineIPhoneImpl body.
#include "AudioEngineIPhoneImpl.h"
#include <AudioUnit/AudioComponent.h>
// http://michael.tyson.id.au/2008/11/04/using-remoteio-audio-unit/
const int kOutputBus = 0;
const int kInputBus = 1;
void AudioEngineIPhoneImpl::createAudioUnit()
{
// Create the audio component instance
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
AudioComponent comp = AudioComponentFindNext(NULL, &desc);
assert(comp);
OSStatus err = AudioComponentInstanceNew(comp, &mAudioUnit);
assert(err == noErr);
}
void AudioEngineIPhoneImpl::enableAudioUnit()
{
// Disable input - flag must be 0 to enable larger speakers,
// otherwise small ear speaker is used.
UInt32 flag = 0;
OSStatus err = AudioUnitSetProperty(mAudioUnit, kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Input, kInputBus, &flag, sizeof(flag));
assert(err == noErr);
// Enable IO for output
flag = 1;
err = AudioUnitSetProperty(mAudioUnit, kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Output, kOutputBus, &flag, sizeof(flag));
assert(err == noErr);
}
Hopefully all that is a good comparison!
Paraphrased from Erica Sadun on TUAW over 2 years ago, but very useful for the newbie.
You want to access a data file in your iphone app. Let’s call it ‘MyAppSettings.xml’. First thing to do is create it and add it into your Xcode Resources folder (although it can physically reside anywhere. This should automatically be added to the ‘Copy Bundle Resources‘ list in your target. When you next build your app, your file will be in the root of your bundle. You can check by going into the app bundle in your build directory. Right-click build/Release-iphoneos/MyApp (for example) and select ‘Show Package Contents‘. You should see your file there.
You find the proper path to this file using the following statement:
[[NSBundle mainBundle] pathForResource:@"MyAppSettings" ofType:@"xml" inDirectory:""]]
This will return a NSString with the full path you need.
I really like most of the developer documentation app that is part of Xcode. It’s nice and fast, better than accessing it from the browser. The part I don’t like is that it crashes far too frequently for a piece of non-beta professional software. And the part I really hate is that when it crashes, it takes the rest of Xcode with it. I’d love to be able to run it externally to Xcode. Even better would be if it didn’t crash! Finally, it’s a bit annoying not being able to cmd-tab between the main IDE window and the docs – if I’ve got more then one other IDE window, cycling to and from the documentation is a pain.
Tags: xcode
Britain looks like it’s had a fine dusting of icing – incredible photo (from BBC article here). This photo was taken by Nasa’s Terra satellite on January the 7th.
Tags: frozen Britain
Alchemy 008 has just been released. You can download it here.
I haven’t had a chance to play with it yet, but the main new feature seems to be the addition of modules. You can add or remove modules as you like, including those you’ve created yourself. Some examples mentioned on the website are:
It’s nearly the weekend now, maybe I can find some free time…
Technorati Tags: alchemy
I’ve spent a lot of time trying to use the same audio renderer for both mac & iphone versions of the synth. I developed the code using float buffers, which I can then feed directly to the audio unit of the mac without issues. However, I’d always had problems doing the same on the iphone – it would come out a bit crackly. Turns out the iphone doesn’t support using float buffers with the audio units.
Now I have to decide whether to continue to use floating point buffers (keeping the bulk of the audio code identical) and converting to ints, to write a separate, int-based note generator, or to move entirely to ints for both platforms.
On the one hand, I find floats more natural to use, but 16-bit ints would use half as much memory, be faster on the iphone (which is after all the intended platform) and perhaps be more suitable in general. Check out this forum discussion on the topic of ints vs floats – I’ve skimmed it, but not fully absorbed it all yet.
For now I’ll probably leave the code the same, but convert the buffer before rendering it. In the future, I’d like to write some solely int-based synth code. Another for the todo list.
Snowy Monkey 