以编程方式获取 AVAudioEngineGraph

Question

在我的应用程序中，我创建了一个 AVAudioEngine 并在其上附加了 AVAudioNodes。

是否可以通过编程方式获取附加节点？
是否可以让节点连接到给定的 AVAudioNode？

当我记录引擎的描述时，我可以看到所有的 AVAudioEngineGraph，但是我找不到以编程方式获取这些信息的方法，有人能给我一个解决方案吗？

(lldb) po _engine

________ GraphDescription ________
AVAudioEngineGraph 0x7fb04541ac60: initialized = 1, running = 1, number of nodes = 4

 ******** output chain ********

 node 0x600002448c00 {'auou' 'rioc' 'appl'}, 'I'
     inputs = 1
         (bus0, en1) <- (bus0) 0x60000244cd00, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 node 0x60000244cd00 {'aumx' 'mcmx' 'appl'}, 'I'
     inputs = 1
         (bus0, en1) <- (bus0) 0x600002473680, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
     outputs = 1
         (bus0, en1) -> (bus0) 0x600002448c00, {'auou' 'rioc' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 node 0x600002473680 {'aumx' 'mcmx' 'appl'}, 'I'
     inputs = 1
         (bus0, en1) <- (bus1) 0x600002462580, {'auou' 'rioc' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
     outputs = 1
         (bus0, en1) -> (bus0) 0x60000244cd00, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 node 0x600002462580 {'auou' 'rioc' 'appl'}, 'I'
     outputs = 2
         (bus0, en0) -> (bus0) 0x0, {}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
         (bus1, en1) -> (bus0) 0x600002473680, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 ******** input chain ********

 node 0x600002462580 {'auou' 'rioc' 'appl'}, 'I'
     outputs = 2
         (bus0, en0) -> (bus0) 0x0, {}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
         (bus1, en1) -> (bus0) 0x600002473680, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 node 0x600002473680 {'aumx' 'mcmx' 'appl'}, 'I'
     inputs = 1
         (bus0, en1) <- (bus1) 0x600002462580, {'auou' 'rioc' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
     outputs = 1
         (bus0, en1) -> (bus0) 0x60000244cd00, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 node 0x60000244cd00 {'aumx' 'mcmx' 'appl'}, 'I'
     inputs = 1
         (bus0, en1) <- (bus0) 0x600002473680, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
     outputs = 1
         (bus0, en1) -> (bus0) 0x600002448c00, {'auou' 'rioc' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

 node 0x600002448c00 {'auou' 'rioc' 'appl'}, 'I'
     inputs = 1
         (bus0, en1) <- (bus0) 0x60000244cd00, {'aumx' 'mcmx' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]

Answer 1

为了管理自定义初始化，我为我要加载的每个类别（或特定）audioUnit 创建了 audioUnit 包装器。这些包装器由工厂提供并由我的应用程序的业务对象引用。

到目前为止我主要使用的包装器是所谓的 AUMIDISynth

componentType = kAudioUnitType_MusicDevice;
componentSubType = kAudioUnitSubType_MIDISynth;
componentManufacturer = kAudioUnitManufacturer_Apple;

允许同时加载和播放来自 soundBank 文件的不同音色。

AUMIDISynth 的子类包装器公开了一个名为

的方法

-(NSError*)loadProgramChange:(uint8_t)programChange channel:(uint8_t)channel;

其他对象（SynthPlayers）观察到从AudioEngine开始发送的通知，并通过调用上述方法响应此通知到自己的audioUnit wrapper实现如下

-(NSError*)loadProgramChange:(uint8_t)programChange channel:(uint8_t)channel{  
    NSError *error;
    if (!self.audioUnit.engine || !self.audioUnit.engine.isRunning) {
        error = [NSError errorWithDomain:NSURLErrorDomain code:-1 userInfo:nil];
    }
    uint32_t enabled = 1;
    OSStatus status = AudioUnitSetProperty(
                                           self.audioUnit.audioUnit,
                                           kAUMIDISynthProperty_EnablePreload,
                                           kAudioUnitScope_Global,
                                           0,
                                           &enabled,
                                           sizeof(enabled));
    if (status != noErr) {
        NSLog(@"error %d",status);
        error = [NSError errorWithDomain:NSURLErrorDomain code:-1 userInfo:nil];
    }
    uint8_t pcCommand = 0xC0 | channel;
    status = MusicDeviceMIDIEvent(self.audioUnit.audioUnit, pcCommand, programChange, 0, 0);
    if (status != noErr) {
        NSLog(@"error %d",status);
        error = [NSError errorWithDomain:NSURLErrorDomain code:-1 userInfo:nil];
    }

    enabled = 0;
    status = AudioUnitSetProperty(
                                  self.audioUnit.audioUnit,
                                  kAUMIDISynthProperty_EnablePreload,
                                  kAudioUnitScope_Global,
                                  0,
                                  &enabled,
                                  sizeof(enabled));
    if (status != noErr) {
        NSLog(@"error %d",status);
        error = [NSError errorWithDomain:NSURLErrorDomain code:-1 userInfo:nil];
    }
    return error;
}

以编程方式获取 AVAudioEngineGraph

Get AVAudioEngineGraph programmatically

objective-c

core-audio

avfoundation

ios