文档建议反馈控制台
首页
学习
活动
专区
圈层
工具
MCP广场
文章/答案/技术大牛
发布
社区首页 >问答首页 >CoreAudio AUGraph没有声音

问CoreAudio AUGraph没有声音
EN

Stack Overflow用户
提问于 2018-05-22 22:21:53
回答 1查看 418关注 0票数 3

我在使用MixerUnit和OutputUnit从MixerUnit和OutputUnit上获取音频时遇到了困难。我已经构建了一个混合了2个音频文件的图表。这是我创建图形的代码。我没有任何错误。

代码语言：javascript
复制
NSLog(@"initializeAUGraph");

mAudioFormat = [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatFloat32
                                                sampleRate:kSampleRate
                                                  channels:2
                                               interleaved:NO];

CheckError(NewAUGraph(&mGraph),"Error creating new graph");

AUNode outputNode;

AudioComponentDescription outputcd = {0};
outputcd.componentType = kAudioUnitType_Output;
outputcd.componentSubType = kAudioUnitSubType_DefaultOutput;
outputcd.componentManufacturer = kAudioUnitManufacturer_Apple;

AudioComponent comp = AudioComponentFindNext(NULL, &outputcd);
if (comp == NULL) {
    printf ("can't get output unit"); exit (-1);
}

AUNode mixerNode;

AudioComponentDescription mixerDescription = {0};
mixerDescription.componentType = kAudioUnitType_Mixer;
mixerDescription.componentSubType = kAudioUnitSubType_MultiChannelMixer;
mixerDescription.componentManufacturer = kAudioUnitManufacturer_Apple;

CheckError(AUGraphAddNode(mGraph, &outputcd, &outputNode), "Error adding Output node to graph");

CheckError(AUGraphAddNode(mGraph, &mixerDescription, &mixerNode), "Error adding Mixer mode to graph");

CheckError(AUGraphOpen(mGraph), "AUGraphOpen failed");

CheckError(AUGraphConnectNodeInput(mGraph, mixerNode, 0, outputNode, 0),"AUGraphConnectModeInput");

CheckError(AUGraphNodeInfo(mGraph, mixerNode, NULL, &mMixer), "Error loading mixer node info");

CheckError(AUGraphNodeInfo(mGraph, outputNode, NULL, &mOutput), "Error loading output node info");

UInt32 numbuses = 2;

CheckError(AudioUnitSetProperty(mMixer, kAudioUnitProperty_ElementCount, kAudioUnitScope_Input, 0, &numbuses, sizeof(numbuses)) , "Error setting prop to mixer");

for (int i = 0; i < numbuses; ++i) {
    // setup render callback struct
    AURenderCallbackStruct renderCallbackStruct;
    renderCallbackStruct.inputProc = &renderAudioInput;
    renderCallbackStruct.inputProcRefCon = mSoundBuffer;

    // Set a callback for the specified node's specified input
    CheckError((AUGraphSetNodeInputCallback(mGraph, mixerNode, i, &renderCallbackStruct))," AUGraphSetNodeInputCallback failed in cycle");

    //Set the input stream format property

   CheckError(AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, i, mAudioFormat.streamDescription, sizeof(AudioStreamBasicDescription)),"Set proprety in cycle error");

}

CheckError(AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, mAudioFormat.streamDescription, sizeof(AudioStreamBasicDescription)), "AudioUnitSetProperty mixer stream format failed");

/*CheckError(AudioUnitSetProperty(mOutput, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, mAudioFormat.streamDescription, sizeof(AudioStreamBasicDescription)), "AudioUnitSetProperty output stream format failed");*/

CheckError(AUGraphInitialize(mGraph),"AUGraphInitialize failed");

控制台输出：

代码语言：javascript
复制
2018-05-23 01:19:22.676281+0300 Mixer2Mac[37249:1285521] loadAudioFiles
2018-05-23 01:19:22.676918+0300 Mixer2Mac[37249:1285521] 2017569 frames in GuitarMonoSTP.aif
2018-05-23 01:19:22.676939+0300 Mixer2Mac[37249:1285521] 2017569 frames after sample ratio multiplied in GuitarMonoSTP.aif
2018-05-23 01:19:22.682277+0300 Mixer2Mac[37249:1285521] 2017569 frames in DrumsMonoSTP.aif
2018-05-23 01:19:22.682303+0300 Mixer2Mac[37249:1285521] 2017569 frames after sample ratio multiplied in DrumsMonoSTP.aif
2018-05-23 01:19:22.687415+0300 Mixer2Mac[37249:1285521] initializeAUGraph
2018-05-23 01:19:23.860541+0300 Mixer2Mac[37249:1285521] startPlaying
2018-05-23 01:19:24.830917+0300 Mixer2Mac[37249:1285521] stopPlaying
2018-05-23 01:19:28.218856+0300 Mixer2Mac[37249:1285521] startPlaying
2018-05-23 01:20:13.009934+0300 Mixer2Mac[37249:1285693] Starting over at frame 0 for bus 0
2018-05-23 01:20:13.010091+0300 Mixer2Mac[37249:1285693] Starting over at frame 0 for bus 1

我看到文件在控制台中播放，但没有听到声音。这款应用是针对MacOs的，而不是针对iOS的。有什么问题吗？

编辑1

这是回调函数。它被称为。我能在控制台上看到它。它打印"LOLLOL“

代码语言：javascript
复制
static OSStatus renderAudioInput(void *inRefCon, AudioUnitRenderActionFlags *actionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberOfFrames, AudioBufferList *ioData)
{
    NSLog(@"LOLLOLO");

    SoundBufferPtr soundBuffer = (SoundBufferPtr)inRefCon;

    //NSLog(@"numberOfFrames: %d", inNumberOfFrames);

    //Get the frame to start at and total number of samples
    UInt32 sample = soundBuffer[inBusNumber].sampleNumber;
    UInt32 startSample = sample;
    UInt32 bufferTotalSamples = soundBuffer[inBusNumber].numberOfFrames;

    //Get a reference to the input data buffer
    Float32 *inputData = soundBuffer[inBusNumber].data; // audio data buffer

    //Get references to the channel buffers
    Float32 *outLeft = (Float32 *)ioData->mBuffers[0].mData; // output audio buffer for Left channel
    Float32 *outRight = (Float32 *)ioData->mBuffers[1].mData; // output audio buffer for Right channel

    //Loop thru the number of frames and set the output data from the input data.
    //Use the left channel for bus 0 (guitar) and right channel for bus 1 (drums) to distiguish for example
    for (UInt32 i = 0; i < inNumberOfFrames; ++i) {

        if (inBusNumber == 0) {
            outLeft[i] = inputData[sample++];
            outRight[i] = 0;
        } else {    //inBusNumber == 1
            outLeft[i] = 0;
            outRight[i] = inputData[sample++];
        }

        //If the sample is beyond the total number of samples in the loop, start over at the beginning
        if (sample > bufferTotalSamples) {
            // start over from the beginning of the data, our audio simply loops
            sample = 0;
            NSLog(@"Starting over at frame 0 for bus %d", (int)inBusNumber);
        }
    }

    //Set the sample number in the sound buffer struct so we know which frame playback is on
    soundBuffer[inBusNumber].sampleNumber = sample;

    performFFT(&inputData[startSample], inNumberOfFrames, soundBuffer, inBusNumber);

    return noErr;
}

NSLog之后的输出(“LOLLOL”)：

代码语言：javascript
复制
2018-05-23 12:56:49.297251+0300 Mixer2Mac[39034:1368659] loadAudioFiles
2018-05-23 12:56:49.298417+0300 Mixer2Mac[39034:1368659] 2017569 frames in GuitarMonoSTP.aif
2018-05-23 12:56:49.298445+0300 Mixer2Mac[39034:1368659] 2017569 frames after sample ratio multiplied in GuitarMonoSTP.aif
2018-05-23 12:56:49.309126+0300 Mixer2Mac[39034:1368659] 2017569 frames in DrumsMonoSTP.aif
2018-05-23 12:56:49.309156+0300 Mixer2Mac[39034:1368659] 2017569 frames after sample ratio multiplied in DrumsMonoSTP.aif
2018-05-23 12:56:49.316572+0300 Mixer2Mac[39034:1368659] initializeAUGraph
2018-05-23 12:56:51.206301+0300 Mixer2Mac[39034:1368659] startPlaying
2018-05-23 12:56:51.229420+0300 Mixer2Mac[39034:1368816] LOLLOLO
2018-05-23 12:56:51.229692+0300 Mixer2Mac[39034:1368816] LOLLOLO
2018-05-23 12:56:51.240977+0300 Mixer2Mac[39034:1368816] LOLLOLO
2018-05-23 12:56:51.241162+0300 Mixer2Mac[39034:1368816] LOLLOLO
core-audio
augraph
xcode
macos
EN

回答 1

Stack Overflow用户

发布于 2018-05-23 05:37:46

New，改进后的应答 这个答案，因为您有两条总线而不是一条，所以它并不完全是重复的。它指出，在macOS上，混频器输入卷默认为零，一条注释还添加了输出卷也是这样，所以请按如下方式修改代码：

代码语言：javascript
复制
for (int i = 0; i < numbuses; ++i) {
    // setup render callback struct
    AURenderCallbackStruct renderCallbackStruct;
    renderCallbackStruct.inputProc = &renderAudioInput;
    renderCallbackStruct.inputProcRefCon = mSoundBuffer;

    // Set a callback for the specified node's specified input
    CheckError((AUGraphSetNodeInputCallback(mGraph, mixerNode, i, &renderCallbackStruct))," AUGraphSetNodeInputCallback failed in cycle");

    //Set the input stream format property

    CheckError(AudioUnitSetProperty(mMixer, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, i, mAudioFormat.streamDescription, sizeof(AudioStreamBasicDescription)),"Set proprety in cycle error");

    // NEW! mixer input volume defaults to zero on macOS. Why!?!?
    CheckError(AudioUnitSetParameter(mMixer, kMultiChannelMixerParam_Volume, kAudioUnitScope_Input, i, 1.0, 0), "AudioUnitSetParameter failed");
}

// NEW! Output defaults to zero too!
CheckError(AudioUnitSetParameter(mMixer, kMultiChannelMixerParam_Volume, kAudioUnitScope_Output, 0, 1.0, 0), "AudioUnitSetParameter failed");

文献资料似乎错误地说kMultiChannelMixerParam_Volume默认为1.0：

全球范围。这个值应该是0.0到1.0之间的一个数字。默认值为1.0。

然而，这是全球范围的问题。

哦，你刚开始的时候，

您需要在初始化音频图之后启动它：

代码语言：javascript
复制
OSStatus status = AUGraphStart(mGraph);
票数 1
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/50477242

复制
相关文章

相似问题

领券

腾讯云开发者

扫码关注腾讯云开发者

扫码关注腾讯云开发者

领取腾讯云代金券

热门产品

热门推荐

更多推荐

Copyright © 2013 - 2026 Tencent Cloud. All Rights Reserved. 腾讯云 版权所有 

深圳市腾讯计算机系统有限公司 ICP备案/许可证号：粤B2-20090059 粤公网安备44030502008569号

腾讯云计算（北京）有限责任公司 京ICP证150476号 |  京ICP备11018762号

问题归档专栏文章快讯文章归档关键词归档开发者手册归档开发者手册 Section 归档