ios - Music TrackSetDestNode 重置旧音乐轨道的采样器声音

Question

我正在制作一个音乐应用程序，您可以在其中向现有音序器添加新乐器。这些乐器是单独的 AudioUnitSampler，存储在一个数组中，因此当加载新乐器和音轨时，它会加载该音轨将要使用的声音。

这就是我目前向 AUGraph 添加轨道的方式。

// Return count as an id for the new track
- (int) addMusicTrack: (MusicTrack)musicTrack withNode:(AUNode)newSamplerNode withAudioUnit:(AudioUnit)newSamplerUnit {

    tracksCount++;
    int trackId = tracksCount;

    MusicPlayerStop(_musicPlayer);
    status = MusicSequenceNewTrack(sequence, &tracks[trackId]);
    MusicSequenceSetAUGraph(sequence, graph);

    if(status){
        printf("Error adding main track: %d", (int)status);
        status = 0;
    }

    timeDiff = 32.f/_tempo;

    [self setLoopDuration:DEFAULT_LOOP_DURATION forTrack:trackId];
    currentOctaveNumber = 59;

    AudioComponentDescription samplerNodeDesc;
    samplerNodeDesc.componentManufacturer = (OSType)kAudioUnitManufacturer_Apple;
    samplerNodeDesc.componentType = (OSType)kAudioUnitType_MusicDevice;
    samplerNodeDesc.componentSubType = (OSType)kAudioUnitSubType_Sampler;
    samplerNodeDesc.componentFlags = 0;
    samplerNodeDesc.componentFlagsMask = 0;
    status = AUGraphAddNode(graph, &samplerNodeDesc, &auSampleNodes[trackId]);

    AudioComponentDescription splitterNodeDesc;
    splitterNodeDesc.componentManufacturer = (OSType)kAudioUnitManufacturer_Apple;
    splitterNodeDesc.componentType = (OSType)kAudioUnitType_FormatConverter;
    splitterNodeDesc.componentSubType = (OSType)kAudioUnitSubType_Splitter;
    splitterNodeDesc.componentFlags = 0;
    splitterNodeDesc.componentFlagsMask = 0;
    status = AUGraphAddNode(graph, &splitterNodeDesc, &splitterNodes[trackId]);

    // node info
    status = AUGraphNodeInfo(graph, auSampleNodes[trackId], 0, &auSampleUnits[trackId]);
    status = AUGraphNodeInfo(graph, splitterNodes[trackId], 0, &splitterUnits[trackId]);

    // connecting nodes samplernode ==> Splitter ==> Mixer
    status = AUGraphConnectNodeInput(graph, auSampleNodes[trackId], 0, splitterNodes[trackId], 0);
    status = AUGraphConnectNodeInput(graph, splitterNodes[trackId], 0, mixerNode, trackId);

    status = MusicTrackSetDestNode(tracks[trackId], auSampleNodes[trackId]);

    status = AUGraphUpdate(graph, NULL);
    if (status) {printf("Error updating graph: %ld\n", status);}

    MusicPlayerStart(_musicPlayer);

    return trackId;
}

这就是我为该轨道加载声音的方式:

[self samplerUnit:auSampleUnits[trackId] loadFromDLSOrSoundFont:url withPatch:patchNumber];

声音字体加载:

- (OSStatus)samplerUnit:(AudioUnit)sampler loadFromDLSOrSoundFont:(NSURL *)bankURL withPatch:(int)presetNumber{

    OSStatus result = noErr;

    // Fill out the sampler instrument data structure
    AUSamplerInstrumentData insdata;
    insdata.fileURL = (__bridge CFURLRef) bankURL;
    insdata.bankMSB  = kAUSampler_DefaultMelodicBankMSB;
    insdata.bankLSB  = (UInt8)0;
    insdata.presetID = (UInt8) presetNumber;
    insdata.instrumentType = kInstrumentType_DLSPreset; // DLS and SF2 are the same enum values

    // Load the instrument
    result = AudioUnitSetProperty(sampler,
                                  kAUSamplerProperty_LoadInstrument,
                                  kAudioUnitScope_Global,
                                  0,
                                  &insdata,
                                  sizeof(insdata));

    NSCAssert (result == noErr,
               @"Unable to set the preset property on the Sampler. Error code: %d",
               (int) result);

    return result;
}

因此，当前会为最近添加的音轨加载适当的声音，但旧音轨的声音现在是默认的 AudioUnitSampler 正弦波声音。

我已经尝试解决这个问题大约一天了，但还没有找到解决方法，是否有解决方案？

干杯!!!

Answer 1

您是否将 trackCount 与 MusicSequenceGetTrackCount 进行了比较？

查看 MusicSequenceSetAUGraph 的文档。“默认情况下，序列中的所有音乐轨道都指向图中的第一个节点，该节点是乐器单元(类型为 DLSMusicDevice”

你想让拆分器做什么？它现在没有做太多事情。