如何将AudioFilePlayer AudioUnit连接到3DMixer？
我试图将AudioFilePlayer AudioUnit连接到AU3DMixerEmbedded Audio Unit，但我没有成功。
以下是我正在做的事情：
用NewAUGraph()创建一个AUGraph
打开图表
初始化图形
添加3个节点：
kAudioUnitSubType_RemoteIO kAudioUnitSubType_AU3DMixerEmbedded kAudioUnitSubType_AudioFilePlayer 连接节点：
配置filePlayer音频单元播放所需的文件
开始图形
这不起作用：它在AUGraphInitialize上出现错误10868（kAudioUnitErr_FormatNotSupported）。 我认为这个问题是由于filePlayer和调音台之间的音频格式不匹配造成的。 我认为这是因为： - 如果我注释掉将filePlayerNode连接到mixerNode（ AUGraphConnectNodeInput(_graph, filePlayerNode, 0, mixerNode, 0) ）并注释掉步骤6，则不报告错误。 - 如果替换第3步，将filePlayerNode直接连接到outputNode（ AUGraphConnectNodeInput(_graph, filePlayerNode, 0, outputNode, 0) ），则会播放音频。
在将filePlayerNode连接到mixerNode时缺少哪些步骤？
这是完整的代码。 它基于苹果公司的示例代码和我从互联网上找到的其他样本。 （ AUGraphStart被称为后者）：
- (id)init
{
self = [super init];
if (self != nil)
{
{
//create a new AUGraph
CheckError(NewAUGraph(&_graph), "NewAUGraph failed");
// opening the graph opens all contained audio units but does not allocate any resources yet
CheckError(AUGraphOpen(_graph), "AUGraphOpen failed");
// now initialize the graph (causes resources to be allocated)
CheckError(AUGraphInitialize(_graph), "AUGraphInitialize failed");
}
AUNode outputNode;
{
AudioComponentDescription outputAudioDesc = {0};
outputAudioDesc.componentManufacturer = kAudioUnitManufacturer_Apple;
outputAudioDesc.componentType = kAudioUnitType_Output;
outputAudioDesc.componentSubType = kAudioUnitSubType_RemoteIO;
// adds a node with above description to the graph
CheckError(AUGraphAddNode(_graph, &outputAudioDesc, &outputNode), "AUGraphAddNode[kAudioUnitSubType_DefaultOutput] failed");
}
AUNode mixerNode;
{
AudioComponentDescription mixerAudioDesc = {0};
mixerAudioDesc.componentManufacturer = kAudioUnitManufacturer_Apple;
mixerAudioDesc.componentType = kAudioUnitType_Mixer;
mixerAudioDesc.componentSubType = kAudioUnitSubType_AU3DMixerEmbedded;
mixerAudioDesc.componentFlags = 0;
mixerAudioDesc.componentFlagsMask = 0;
// adds a node with above description to the graph
CheckError(AUGraphAddNode(_graph, &mixerAudioDesc, &mixerNode), "AUGraphAddNode[kAudioUnitSubType_AU3DMixerEmbedded] failed");
}
AUNode filePlayerNode;
{
AudioComponentDescription fileplayerAudioDesc = {0};
fileplayerAudioDesc.componentType = kAudioUnitType_Generator;
fileplayerAudioDesc.componentSubType = kAudioUnitSubType_AudioFilePlayer;
fileplayerAudioDesc.componentManufacturer = kAudioUnitManufacturer_Apple;
// adds a node with above description to the graph
CheckError(AUGraphAddNode(_graph, &fileplayerAudioDesc, &filePlayerNode), "AUGraphAddNode[kAudioUnitSubType_AudioFilePlayer] failed");
}
//Connect the nodes
{
// connect the output source of the file player AU to the input source of the output node
// CheckError(AUGraphConnectNodeInput(_graph, filePlayerNode, 0, outputNode, 0), "AUGraphConnectNodeInput");
CheckError(AUGraphConnectNodeInput(_graph, filePlayerNode, 0, mixerNode, 0), "AUGraphConnectNodeInput");
CheckError(AUGraphConnectNodeInput(_graph, mixerNode, 0, outputNode, 0), "AUGraphConnectNodeInput");
}
// configure the file player
// tell the file player unit to load the file we want to play
{
//?????
AudioStreamBasicDescription inputFormat; // input file's data stream description
AudioFileID inputFile; // reference to your input file
// open the input audio file and store the AU ref in _player
CFURLRef songURL = (__bridge CFURLRef)[[NSBundle mainBundle] URLForResource:@"monoVoice" withExtension:@"aif"];
CheckError(AudioFileOpenURL(songURL, kAudioFileReadPermission, 0, &inputFile), "AudioFileOpenURL failed");
//create an empty MyAUGraphPlayer struct
AudioUnit fileAU;
// get the reference to the AudioUnit object for the file player graph node
CheckError(AUGraphNodeInfo(_graph, filePlayerNode, NULL, &fileAU), "AUGraphNodeInfo failed");
// get and store the audio data format from the file
UInt32 propSize = sizeof(inputFormat);
CheckError(AudioFileGetProperty(inputFile, kAudioFilePropertyDataFormat, &propSize, &inputFormat), "couldn't get file's data format");
CheckError(AudioUnitSetProperty(fileAU, kAudioUnitProperty_ScheduledFileIDs, kAudioUnitScope_Global, 0, &(inputFile), sizeof((inputFile))), "AudioUnitSetProperty[kAudioUnitProperty_ScheduledFileIDs] failed");
UInt64 nPackets;
UInt32 propsize = sizeof(nPackets);
CheckError(AudioFileGetProperty(inputFile, kAudioFilePropertyAudioDataPacketCount, &propsize, &nPackets), "AudioFileGetProperty[kAudioFilePropertyAudioDataPacketCount] failed");
// tell the file player AU to play the entire file
ScheduledAudioFileRegion rgn;
memset (&rgn.mTimeStamp, 0, sizeof(rgn.mTimeStamp));
rgn.mTimeStamp.mFlags = kAudioTimeStampSampleTimeValid;
rgn.mTimeStamp.mSampleTime = 0;
rgn.mCompletionProc = NULL;
rgn.mCompletionProcUserData = NULL;
rgn.mAudioFile = inputFile;
rgn.mLoopCount = 1;
rgn.mStartFrame = 0;
rgn.mFramesToPlay = nPackets * inputFormat.mFramesPerPacket;
CheckError(AudioUnitSetProperty(fileAU, kAudioUnitProperty_ScheduledFileRegion, kAudioUnitScope_Global, 0,&rgn, sizeof(rgn)), "AudioUnitSetProperty[kAudioUnitProperty_ScheduledFileRegion] failed");
// prime the file player AU with default values
UInt32 defaultVal = 0;
CheckError(AudioUnitSetProperty(fileAU, kAudioUnitProperty_ScheduledFilePrime, kAudioUnitScope_Global, 0, &defaultVal, sizeof(defaultVal)), "AudioUnitSetProperty[kAudioUnitProperty_ScheduledFilePrime] failed");
// tell the file player AU when to start playing (-1 sample time means next render cycle)
AudioTimeStamp startTime;
memset (&startTime, 0, sizeof(startTime));
startTime.mFlags = kAudioTimeStampSampleTimeValid;
startTime.mSampleTime = -1;
CheckError(AudioUnitSetProperty(fileAU, kAudioUnitProperty_ScheduleStartTimeStamp, kAudioUnitScope_Global, 0, &startTime, sizeof(startTime)), "AudioUnitSetProperty[kAudioUnitProperty_ScheduleStartTimeStamp]");
// file duration
//double duration = (nPackets * _player.inputFormat.mFramesPerPacket) / _player.inputFormat.mSampleRate;
}
}
return self;
}
我没有在代码中看到为音频单元设置适当的kAudioUnitProperty_StreamFormat。 您还必须检查错误结果代码，以确定您选择的流格式设置是否实际上由正在配置的音频设备支持。 如果不是，请尝试其他格式。
（AUGraphConnectNodeInput（_graph，filePlayerNode，0，mixerNode，0））（AUGraphConnectNodeInput（_graph，mixerNode，0，outputNode，0））
尝试这样做，如果它可以帮助。只是为了信息左节点输入在正确的节点。 所以在第一行中，播放器节点被输入到混合器节点，现在混合器节点包含播放器和混合器，因此将混合器节点添加到输出节点。
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