关于iPhone：RemoteIO音频问题-模拟器=良好-设备=不良

RemoteIO Audio Problem - simulator = good - device= bad

O.K，所以我正在使用核心音频从10个不同的样本源中提取音频，然后在我的回调函数中将它们混合在一起。

它在模拟器中运行完美，一切都很好。但是，当我尝试在4.2 iphone设备上运行它时遇到了麻烦。

如果我在回调中混合2个音频文件，一切正常。
如果我混合了5或6个音频文件，则会播放音频，但是经过短时间后，音频会降级，最终音频将不会到达扬声器。 (回调不会停止)。

如果我尝试混合10个音频文件，则会运行回调，但根本没有音频输出。

这几乎就像回调用尽了时间，这可能解释了我混音5或6的情况，却无法解释混音10个音频源而根本不播放音频的最后一种情况。

我不确定以下内容是否有影响，但是在调试时，此消息始终显示在控制台上。这可以说明问题是什么吗？

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mem 0x1000 0x3fffffff cache
mem 0x40000000 0xffffffff none
mem 0x00000000 0x0fff none
run
Running…
[Switching to thread 11523]
[Switching to thread 11523]
Re-enabling shared library breakpoint 1
continue
warning: Unable to read symbols for /Developer/Platforms/iPhoneOS.platform/DeviceSupport/4.2.1 (8C148)/Symbols/usr/lib/info/dns.so (file not found).

**设置我的回调**

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#pragma mark -
#pragma mark Callback setup & control

- (void) setupCallback

{
OSStatus status;

// Describe audio component
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;

// Get component
AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);

// Get audio units
status = AudioComponentInstanceNew(inputComponent, &audioUnit);

UInt32 flag = 1;
// Enable IO for playback
status = AudioUnitSetProperty(audioUnit,
kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Output,
kOutputBus,
&flag,
sizeof(flag));

//Apply format
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Input,
kOutputBus,
&stereoStreamFormat,
sizeof(stereoStreamFormat));

// Set up the playback callback
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = playbackCallback; //!!****assignment from incompatible pointer warning here *****!!!!!!
//set the reference to"self" this becomes *inRefCon in the playback callback
callbackStruct.inputProcRefCon = self;

status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_SetRenderCallback,
kAudioUnitScope_Global,
kOutputBus,
&callbackStruct,
sizeof(callbackStruct));

// Initialise
status = AudioUnitInitialize(audioUnit); // error check this status

}

回叫

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static OSStatus playbackCallback (

void *inRefCon, // A pointer to a struct containing the complete audio data
// to play, as well as state information such as the
// first sample to play on this invocation of the callback.
AudioUnitRenderActionFlags *ioActionFlags, // Unused here. When generating audio, use ioActionFlags to indicate silence
// between sounds; for silence, also memset the ioData buffers to 0.
AudioTimeStamp *inTimeStamp, // Unused here.
UInt32 inBusNumber, // The mixer unit input bus that is requesting some new
// frames of audio data to play.
UInt32 inNumberFrames, // The number of frames of audio to provide to the buffer(s)
// pointed to by the ioData parameter.
AudioBufferList *ioData // On output, the audio data to play. The callback's primary
// responsibility is to fill the buffer(s) in the
// AudioBufferList.
) {

Engine *remoteIOplayer = (Engine *)inRefCon;
AudioUnitSampleType *outSamplesChannelLeft;
AudioUnitSampleType *outSamplesChannelRight;

outSamplesChannelLeft = (AudioUnitSampleType *) ioData->mBuffers[0].mData;
outSamplesChannelRight = (AudioUnitSampleType *) ioData->mBuffers[1].mData;

int thetime =0;
thetime=remoteIOplayer.sampletime;

for (int frameNumber = 0; frameNumber < inNumberFrames; ++frameNumber)
{
// get NextPacket returns a 32 bit value, one frame.
AudioUnitSampleType *suml=0;
AudioUnitSampleType *sumr=0;

//NSLog (@"frame number - %i", frameNumber);
for(int j=0;j<10;j++)

{

AudioUnitSampleType valuetoaddl=0;
AudioUnitSampleType valuetoaddr=0;

//valuetoadd = [remoteIOplayer getSample:j ];
valuetoaddl = [remoteIOplayer getNonInterleavedSample:j currenttime:thetime channel:0 ];
//valuetoaddl = [remoteIOplayer getSample:j];
valuetoaddr = [remoteIOplayer getNonInterleavedSample:j currenttime:thetime channel:1 ];

suml = suml+(valuetoaddl/10);
sumr = sumr+(valuetoaddr/10);

}

outSamplesChannelLeft[frameNumber]=(AudioUnitSampleType) suml;
outSamplesChannelRight[frameNumber]=(AudioUnitSampleType) sumr;

remoteIOplayer.sampletime +=1;

}

return noErr;
}

我的音频获取功能

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-(AudioUnitSampleType) getNonInterleavedSample:(int) index currenttime:(int)time channel:(int)ch;

{

AudioUnitSampleType returnvalue= 0;

soundStruct snd=soundStructArray[index];
UInt64 sn= snd.frameCount;
UInt64 st=sampletime;
UInt64 read= (UInt64)(st%sn);

if(ch==0)
{
if (snd.sendvalue==1) {
returnvalue = snd.audioDataLeft[read];

}else {
returnvalue=0;
}

}else if(ch==1)

{
if (snd.sendvalue==1) {
returnvalue = snd.audioDataRight[read];
}else {
returnvalue=0;
}

soundStructArray[index].sampleNumber=read;
}

if(soundStructArray[index].sampleNumber >soundStructArray[index].frameCount)
{
soundStructArray[index].sampleNumber=0;

}

return returnvalue;

}

编辑1

作为对@andre的响应，我将回调更改为以下内容，但仍然没有帮助。

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static OSStatus playbackCallback (

void *inRefCon, // A pointer to a struct containing the complete audio data
// to play, as well as state information such as the
// first sample to play on this invocation of the callback.
AudioUnitRenderActionFlags *ioActionFlags, // Unused here. When generating audio, use ioActionFlags to indicate silence
// between sounds; for silence, also memset the ioData buffers to 0.
AudioTimeStamp *inTimeStamp, // Unused here.
UInt32 inBusNumber, // The mixer unit input bus that is requesting some new
// frames of audio data to play.
UInt32 inNumberFrames, // The number of frames of audio to provide to the buffer(s)
// pointed to by the ioData parameter.
AudioBufferList *ioData // On output, the audio data to play. The callback's primary
// responsibility is to fill the buffer(s) in the
// AudioBufferList.
) {

Engine *remoteIOplayer = (Engine *)inRefCon;
AudioUnitSampleType *outSamplesChannelLeft;
AudioUnitSampleType *outSamplesChannelRight;

outSamplesChannelLeft = (AudioUnitSampleType *) ioData->mBuffers[0].mData;
outSamplesChannelRight = (AudioUnitSampleType *) ioData->mBuffers[1].mData;

int thetime =0;
thetime=remoteIOplayer.sampletime;

for (int frameNumber = 0; frameNumber < inNumberFrames; ++frameNumber)
{
// get NextPacket returns a 32 bit value, one frame.
AudioUnitSampleType suml=0;
AudioUnitSampleType sumr=0;

//NSLog (@"frame number - %i", frameNumber);
for(int j=0;j<16;j++)

{

soundStruct snd=remoteIOplayer->soundStructArray[j];
UInt64 sn= snd.frameCount;
UInt64 st=remoteIOplayer.sampletime;
UInt64 read= (UInt64)(st%sn);

suml+= snd.audioDataLeft[read];
suml+= snd.audioDataRight[read];

}

outSamplesChannelLeft[frameNumber]=(AudioUnitSampleType) suml;
outSamplesChannelRight[frameNumber]=(AudioUnitSampleType) sumr;

remoteIOplayer.sampletime +=1;

}

return noErr;
}

就像安德烈所说，最好不要在回调中进行任何Objective-C函数调用。您还应该将inputProcRefCon更改为C结构而不是Objective-C对象。

此外，您似乎可能要逐帧"手动"将数据复制到缓冲区中。而是使用memcopy在其中复制数据块。

此外，我很确定您没有在回调中执行磁盘I / O，但是如果您这样做，您也不应执行此操作。