无法通过AVAudioEngine连接AVAudioUnitEffect

问题描述

我一直在闲逛AVAudioEngine，但在集成AVAudioUnitEffect类时遇到了麻烦.例如，使用AVAudioUnitDelay ...

I've been poking around with AVAudioEngine and I'm having trouble integrating AVAudioUnitEffect classes. For example, with AVAudioUnitDelay...

@implementation ViewController {
AVAudioEngine *engine;
AVAudioPlayerNode *player;
}

...

- (IBAction)playButtonHit:(id)sender {
if (!player){
    NSURL *bandsURL = [[NSBundle mainBundle] URLForResource:@"Bands With Managers" withExtension:@"mp3"];
    AVAudioFile *file = [[AVAudioFile alloc] initForReading:bandsURL error:nil];

    engine = [[AVAudioEngine alloc] init];
    player = [[AVAudioPlayerNode alloc] init];
    [engine attachNode:player];

    AVAudioUnitDelay *delay = [[AVAudioUnitDelay alloc] init];
    delay.wetDryMix = 50;

    [engine connect:player to:delay format:file.processingFormat];
    [engine connect:delay to:[engine outputNode] format:file.processingFormat];

    [player scheduleFile:file atTime:nil completionHandler:nil];
    [engine prepare];
    [engine startAndReturnError:nil];
}
[player play];  

}

调用该方法时，应用程序崩溃，并且出现以下错误:" * 由于未捕获的异常'com.apple.coreaudio.avfaudio'，终止应用程序，原因:'所需条件为假: [_nodes containsObject:node1]&& [_nodes containsObject:node2]'"

When the method is called the app crashes and I get this error: "* Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'required condition is false: [_nodes containsObject: node1] && [_nodes containsObject: node2]'"

在WWDC的"AVAudioEngine in Practice"会议中的一些示例之后，我对此进行了建模.我知道我可能遗漏了一些明显的东西，但无法弄清楚....

I'm modeling this after some of the examples from the "AVAudioEngine in Practice" session from WWDC. I know there's probably something obvious I'm missing but can't figure it out....

推荐答案

这不是AVAudioUnitEffect的问题！我用该代码尝试过

It is not a problem of the AVAudioUnitEffect! I tried it with that code

NSError *err = nil;

self.engine = [[AVAudioEngine alloc] init];
AVAudioPlayerNode *player = [[AVAudioPlayerNode alloc] init];
[self.engine attachNode:player];

NSURL *fileURL = [[NSBundle mainBundle] URLForResource:@"sound" withExtension:@"m4a"];
AVAudioFile *file = [[AVAudioFile alloc] initForReading:fileURL error:&err];

AVAudioMixerNode *mainMixer = [self.engine mainMixerNode];
[self.engine connect:player to:mainMixer format:file.processingFormat];

[player scheduleFile:file atTime:nil completionHandler:nil];

[self.engine startAndReturnError:&err];

if (err != nil) {
    NSLog(@"An error occured");
}

[player play];

而self.engine是由

@property (nonatomic, strong) AVAudioEngine *engine;

我认为这是AVAudioEngine中的一个错误，因为它会导致内存泄漏:它开始播放第一个样本，然后由于内存使用过多而崩溃(在我的16 kB m4a文件中超过300 MB ).

I think that is a bug in AVAudioEngine, because it causes a memory leak: It starts playing the first samples and then it crashes because of heavy memory usage (more than 300 MB in my case of a 16 kB m4a file).

更新2014年12月7日:苹果使用iOS 8 Seed 3(内部版本12A4318c)修复了此问题！

Update 12/07/2014: Apple fixed this issue with iOS 8 Seed 3 (Build 12A4318c)!

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