Remote IO Play with constant noise - core-audio

Question

guys! I have a trouble with using remote IO to playback a stream audio.I verified the PCM frame data before I put it in,it's correct.So I'm confused.Could you help me? Thanks a lot!
Below is my codes.
-
(void)initializeAudioPlay
{
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, &audioPlayUnit);
[self checkStatus:status];
// Enable IO for playback
UInt32 flag = 1;
//kAUVoiceIOProperty_VoiceProcessingEnableAGC
status = AudioUnitSetProperty(audioPlayUnit, kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Input, kOutputBus, &flag, sizeof(flag));
[self checkStatus:status];
// Describe format
AudioStreamBasicDescription audioFormat;
memset(&audioFormat, 0, sizeof(audioFormat));
audioFormat.mSampleRate = 8000;
audioFormat.mFormatID = kAudioFormatLinearPCM;
audioFormat.mFormatFlags = kAudioFormatFlagsCanonical;//kAudioFormatFlagIsNonInterleaved | kAudioFormatFlagIsSignedInteger;
/*kAudioFormatFlagsCanonical
| (kAudioUnitSampleFractionBits << kLinearPCMFormatFlagsSampleFractionShift)*/
audioFormat.mFramesPerPacket = 1;
audioFormat.mChannelsPerFrame = 1;
audioFormat.mBitsPerChannel = 16;
audioFormat.mBytesPerFrame = (audioFormat.mBitsPerChannel/8) * audioFormat.mChannelsPerFrame;
audioFormat.mBytesPerPacket = audioFormat.mBytesPerFrame;
// Apply format
status = AudioUnitSetProperty(audioPlayUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Input,
kOutputBus,
&audioFormat,
sizeof(audioFormat));
[self checkStatus:status];
float value = (float)10 / 255.0;
AudioUnitSetParameter(audioPlayUnit, kAudioUnitParameterUnit_LinearGain, kAudioUnitScope_Input, 0, value, 0);
AudioChannelLayout new_layout;
new_layout.mChannelLayoutTag = kAudioChannelLayoutTag_Mono;
AudioUnitSetProperty( audioPlayUnit,
kAudioUnitProperty_AudioChannelLayout,
kAudioUnitScope_Global,
0, &new_layout, sizeof(new_layout) );
UInt32 bypassEffect = kAudioUnitProperty_RenderQuality;
status = AudioUnitSetProperty(audioPlayUnit,
kAudioUnitProperty_RenderQuality,
kAudioUnitScope_Global,
0,
&bypassEffect,
sizeof(bypassEffect));
[self checkStatus:status];
// Set output callback
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = playCallback;
callbackStruct.inputProcRefCon = self;
status = AudioUnitSetProperty(audioPlayUnit,
kAudioUnitProperty_SetRenderCallback,
kAudioUnitScope_Input,
kOutputBus,
&callbackStruct,
sizeof(callbackStruct));
[self checkStatus:status];
flag = 0;
// Initialize
status = AudioUnitInitialize(audioPlayUnit);
[self checkStatus:status];
DGLog(#"audio play unit initialize = %d", status);
circularBuf = [[CircularBuf alloc] initWithBufLen:kBufferLength];
/*
AudioSessionInitialize(NULL, NULL, NULL, NULL);
Float64 rate =32000.0;
AudioSessionSetProperty(kAudioSessionProperty_PreferredHardwareSampleRate, sizeof(rate), &rate);
Float32 volume=20.0;
UInt32 size = sizeof(Float32);
AudioSessionSetProperty(
kAudioSessionProperty_PreferredHardwareIOBufferDuration,
&size, &volume);
//float aBufferLength = 0.185759637188209;
//AudioSessionSetProperty(kAudioSessionProperty_PreferredHardwareIOBufferDuration, sizeof(aBufferLength), &aBufferLength);
AudioSessionSetActive(YES);
*/
AudioSessionInitialize(NULL, NULL, NULL, nil);
AudioSessionSetActive(true);
UInt32 sessionCategory = kAudioSessionCategory_MediaPlayback ;
/* for Iphone we need to do this to route the audio to speaker */
status= AudioSessionSetProperty (
kAudioSessionProperty_AudioCategory,
sizeof (sessionCategory),
&sessionCategory
);
//NSLog(#"Error: %d", status);
//
// UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
// status = AudioSessionSetProperty (
// kAudioSessionProperty_OverrideAudioRoute,
// sizeof (audioRouteOverride),
// &audioRouteOverride);
UInt32 audioMixed = 1;
status = AudioSessionSetProperty (
kAudioSessionProperty_OverrideCategoryMixWithOthers,
sizeof (audioMixed),
&audioMixed);
}
- (void)processAudio:(AudioBuffer *)buffer
{
short pcmTemp[160];
unsigned char * amrBuffer=NULL;
AudioUnitSampleType sample;
int i = 0;
int j = 0;
if ([circularBuf isReadTwoRegion]) {
amrBuffer = [circularBuf ReadData];
} else {
amrBuffer = [circularBuf ReadData];
i = [circularBuf ReadPos];
}
j = i + circularBuf.Length;
if (j - i >= 320) {
memcpy((void*)pcmTemp, (void*)amrBuffer, 320);
for(i=0; i<160; i++)
{
sample = 3.162277*pcmTemp[i];//10db
if(sample > 32767)sample = 32767;
else if(sample < -32768)sample = -32768;
buffData[i] = sample;
}
memcpy(buffer->mData, buffData, buffer->mDataByteSize);
[circularBuf AdvanceReadPos:320];
}
else
{
memset(buffer->mData, 0, buffer->mDataByteSize);
}
}
/**
This callback is called when the audioUnit needs new data to play through the
speakers. If you don't have any, just don't write anything in the buffers
*/
static OSStatus playCallback(void *inRefCon,
AudioUnitRenderActionFlags *ioActionFlags,
const AudioTimeStamp *inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList *ioData) {
// Notes: ioData contains buffers (may be more than one!)
// Fill them up as much as you can. Remember to set the size value in each buffer to match how
// much data is in the buffer.
AudioPlay *audioPlay = (AudioPlay *)inRefCon;
for ( int i=0; i < ioData->mNumberBuffers; i++ ) {
memset(ioData->mBuffers[i].mData, 0, ioData->mBuffers[i].mDataByteSize);
}
ioData->mBuffers[0].mNumberChannels = 1;
[audioPlay processAudio:&ioData->mBuffers[0]];
return noErr;
}