[修正]IOS中使用SoundTouch库实现变声

 之前写过一片文章“IOS中使用SoundTouch库实现变声”。

最后有很多朋友在博客上说发出来的代码在模拟器上运行可以，不能在真机上运行，前段时间一直也很忙，没时间翻代码出来查看，望谅解。

今天抽空检查了一下问题的根源，并且在IPhone 4（ios5.0.1）上测试通过，下面更新一些代码。
同样是Apple官方的SpeakHere，要下载代码的，请查看上一篇文章。

void AQRecorder::StartRecord(CFStringRef inRecordFile)
{
mSoundTouch.setSampleRate(44100);//mRecordFormat.mSampleRate
mSoundTouch.setChannels(1);//mRecordFormat.mChannelsPerFrame
mSoundTouch.setTempoChange(1.0);
mSoundTouch.setPitchSemiTones(9);
mSoundTouch.setRateChange(-0.7);

mSoundTouch.setSetting(SETTING_SEQUENCE_MS, 40);
mSoundTouch.setSetting(SETTING_SEEKWINDOW_MS, 16);
mSoundTouch.setSetting(SETTING_OVERLAP_MS, 8);

//Only use one of the following two options
// mSoundTouch.setSetting(SETTING_USE_QUICKSEEK, 0);
// mSoundTouch.setSetting(SETTING_USE_AA_FILTER, !(0));
// mSoundTouch.setSetting(SETTING_AA_FILTER_LENGTH, 32);

红色的两行很重要，需要指明采样率和声道。如果需要使用后面注释两个变量，需要在SetupAudioFormat方法执行之后才可以，否则无效，原因大家都懂的。

将麦克风捕捉的声音回调函数按照一下代码更新。
// ____________________________________________________________________________________
// AudioQueue callback function, called when an input buffers has been filled.
void AQRecorder::MyInputBufferHandler( void * inUserData,
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer,
const AudioTimeStamp * inStartTime,
UInt32 inNumPackets,
const AudioStreamPacketDescription* inPacketDesc)
{

AQRecorder *aqr = (AQRecorder *)inUserData;
try {
if (inNumPackets > 0) {
UInt32 audioDataByteSize = inBuffer->mAudioDataByteSize;
CAStreamBasicDescription queueFormat = aqr->DataFormat();
SoundTouch *soundTouch = aqr->GetSoundTouch();

uint nSamples = audioDataByteSize/queueFormat.mBytesPerPacket;
soundTouch->putSamples((const SAMPLETYPE *)inBuffer->mAudioData,nSamples);

SAMPLETYPE *samples = (SAMPLETYPE *)malloc(audioDataByteSize);
UInt32 numSamples;
do {
memset(samples, 0, audioDataByteSize);
numSamples = soundTouch->receiveSamples((SAMPLETYPE *)samples, nSamples);
// write packets to file
XThrowIfError(AudioFileWritePackets(aqr->mRecordFile,
FALSE,
numSamples*queueFormat.mBytesPerPacket,
NULL,
aqr->mRecordPacket,
&numSamples,
samples),
"AudioFileWritePackets failed");
aqr->mRecordPacket += numSamples;
} while (numSamples!=0);
free(samples);
}

// if we're not stopping, re-enqueue the buffe so that it gets filled again
if (aqr->IsRunning())
XThrowIfError(AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL), "AudioQueueEnqueueBuffer failed");
} catch (CAXException e) {
char buf[256];
fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf));
}
} 原因大家自己应该能看明白。

之前是在xcode 3.x上写的代码，刚开始有朋友反馈时，我以为是版本问题产生的，结果不是。

本次更新的代码是我在xcode4.2和iphone4上测试无误的，如果还有问题的，可以仔细看看前后两篇文章。不要吧参数设置错误了。

ps：QQ经常不在线，有问题上微博：http://weibo.com/yarin