Question

我正在尝试播放8000hz样本并通过效果传递它们。
我的目标是提高音量（示例代码不会这样做，还）我想我需要一个效果音频单元，链接到远程音频单元我还读到效果单元对它可以处理的格式非常严格，主要需要44.1khz样本，浮点和32位样本（。
所以，我添加了一个转换器单元此外，因为我想（不确定）iOS无法播放32位样本（感谢@ hotpaw2！） - 我添加了另一个转换回16位。问题是，我在初始化音频图时总是得到错误-10868 我没有最后一个转换单元也能得到它如果我将转换单元连接到输出（无效果单元），一切正常（8k样本播放就好了）发生了什么事？

    /* Must use play & record category, for reasons beyond the scope of this question */
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDuckOthers | AVAudioSessionCategoryOptionDefaultToSpeaker | AVAudioSessionCategoryOptionAllowBluetooth error:nil];
    NSError* err = nil;
    if (![[AVAudioSession sharedInstance] setPreferredSampleRate:44100 error:&err]){
        NSLog(@"%@",err);
    }
    AudioUnit effect,convert,output,oconvert;
    AUNode neffect,nconvert,noutput,noconvert;
    AUGraph graph;
    AudioComponentDescription deffect,dconvert,doutput;
    AudioStreamBasicDescription in_format,out_format,effect_format;
    // Formats
    memset(&in_format,0,sizeof(in_format));
    memset(&out_format, 0, sizeof(out_format));
    memset(&effect_format, 0, sizeof(effect_format));
    in_format.mSampleRate = 8000;
    in_format.mChannelsPerFrame = 1;
    in_format.mFormatID = kAudioFormatLinearPCM;
    in_format.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked;
    in_format.mBitsPerChannel = 16;
    in_format.mFramesPerPacket = 1;
    in_format.mBytesPerFrame = in_format.mChannelsPerFrame * (in_format.mBitsPerChannel / 8);
    in_format.mBytesPerPacket = in_format.mBytesPerFrame * in_format.mFramesPerPacket;
    out_format.mSampleRate = 44100;
    out_format.mChannelsPerFrame = 1;
    out_format.mFormatID = kAudioFormatLinearPCM;
    out_format.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked;
    out_format.mBitsPerChannel = 16;
    out_format.mFramesPerPacket = 1;
    out_format.mBytesPerFrame = out_format.mChannelsPerFrame * (out_format.mBitsPerChannel / 8);
    out_format.mBytesPerPacket = out_format.mBytesPerFrame * out_format.mFramesPerPacket;
    effect_format.mSampleRate = 44100;
    effect_format.mChannelsPerFrame = 1;
    effect_format.mFormatID = kAudioFormatLinearPCM;
    effect_format.mFormatFlags = kAudioFormatFlagsNativeFloatPacked;
    effect_format.mBitsPerChannel = 32;
    effect_format.mFramesPerPacket = 1;
    effect_format.mBytesPerFrame = effect_format.mChannelsPerFrame * (effect_format.mBitsPerChannel / 8);
    effect_format.mBytesPerPacket = effect_format.mBytesPerFrame * effect_format.mFramesPerPacket;

    // Descriptions
    memset(&doutput, 0, sizeof(doutput));
    memset(&deffect, 0, sizeof(deffect));
    memset(&dconvert, 0, sizeof(dconvert));
    doutput.componentType = kAudioUnitType_Output;
    doutput.componentSubType = kAudioUnitSubType_RemoteIO;
    doutput.componentManufacturer = deffect.componentManufacturer = dconvert.componentManufacturer = kAudioUnitManufacturer_Apple;
    dconvert.componentType = kAudioUnitType_FormatConverter;
    dconvert.componentSubType = kAudioUnitSubType_AUConverter;
    deffect.componentType = kAudioUnitType_Effect;
    deffect.componentSubType = kAudioUnitSubType_DynamicsProcessor;
    // Create graph
    SdCheck(NewAUGraph(&graph));

    // Create nodes;
    SdCheck(AUGraphAddNode(graph, &deffect, &neffect));
    SdCheck(AUGraphAddNode(graph, &doutput, &noutput));
    SdCheck(AUGraphAddNode(graph, &dconvert, &nconvert));
    SdCheck(AUGraphAddNode(graph, &dconvert, &noconvert));
    // Open graph
    SdCheck(AUGraphOpen(graph));
    // Get units
    SdCheck(AUGraphNodeInfo(graph, neffect,NULL, &effect));
    SdCheck(AUGraphNodeInfo(graph, noutput,NULL, &output));
    SdCheck(AUGraphNodeInfo(graph, nconvert,NULL, &convert));
    SdCheck(AUGraphNodeInfo(graph, noconvert,NULL, &oconvert));
    // Set formats
    SdCheck(AudioUnitSetProperty (output,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Input,
                                  0,
                                  &out_format,
                                  sizeof(out_format)));
    SdCheck(AudioUnitSetProperty (convert,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Input,
                                  0,
                                  &effect_format,
                                  sizeof(effect_format)));
    SdCheck(AudioUnitSetProperty (convert,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Output,
                                  0,
                                  &in_format,
                                  sizeof(in_format)));
    SdCheck(AudioUnitSetProperty (effect,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Input,
                                  0,
                                  &effect_format,
                                  sizeof(effect_format)));
    SdCheck(AudioUnitSetProperty (effect,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Output,
                                  0,
                                  &effect_format,
                                  sizeof(effect_format)));
    SdCheck(AudioUnitSetProperty (oconvert,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Input,
                                  0,
                                  &out_format,
                                  sizeof(out_format)));
    SdCheck(AudioUnitSetProperty (oconvert,
                                  kAudioUnitProperty_StreamFormat,
                                  kAudioUnitScope_Output,
                                  0,
                                  &effect_format,
                                  sizeof(effect_format)));

    // Connect nodes
    SdCheck(AUGraphConnectNodeInput(graph, nconvert, 0, neffect, 0));
    SdCheck(AUGraphConnectNodeInput(graph, neffect, 0, noconvert, 0));
    SdCheck(AUGraphConnectNodeInput(graph, noconvert, 0, noutput, 0));
    // Set render callback
    AURenderCallbackStruct input;
    memset(&input, 0, sizeof(input));
    input.inputProc = SdInputProc;
    input.inputProcRefCon = (__bridge void*)self;
    SdCheck(AUGraphSetNodeInputCallback(graph, nconvert, 0, &input));
    // Initialize graph
    /*** The following fails with error -10868 (unsupported format) ***/
    SdCheck(AUGraphInitialize(graph));

Answer 1

iOS上的大多数效果音频单元要求在其输入和输出连接上使用32位浮点格式。您的示例代码尝试使用16位整数I / O配置效果单元，这将无效。

如何使用效果音频装置？

1 个答案: