如何从内置音频输入捕获音频,并能够实时读取原始采样值(例如.wav),就像从套接字中读取一样。
希望使用苹果的框架之一(Audio Queues)编写代码。文档不是很清楚,我需要的非常基础。
如何从内置音频输入捕获音频,并能够实时读取原始采样值(例如.wav),就像从套接字中读取一样。
希望使用苹果的框架之一(Audio Queues)编写代码。文档不是很清楚,我需要的非常基础。
static void HandleAudioCallback (void *aqData,
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer,
const AudioTimeStamp *inStartTime,
UInt32 inNumPackets,
const AudioStreamPacketDescription *inPacketDesc) {
// Here you examine your audio data
}
static void StartRecording() {
// now let's start the recording
AudioQueueNewInput (&aqData.mDataFormat, // The sampling format how to record
HandleAudioCallback, // Your callback routine
&aqData, // e.g. AudioStreamBasicDescription
NULL,
kCFRunLoopCommonModes,
0,
&aqData.mQueue); // Your fresh created AudioQueue
AudioQueueStart(aqData.mQueue,
NULL);
}
这取决于你需要多实时的程度。如果需要非常精准的实时性,可以在底层使用音频单元。这意味着设置一个输入回调函数。请注意,当该回调被触发时,您需要分配自己的缓冲区,然后从麦克风请求音频。
不要被参数中存在缓冲指针所迷惑...这只是因为苹果正在使用相同的函数声明来处理输入和渲染回调函数。
以下是我其中一个项目的剪切版:
OSStatus dataArrivedFromMic(
void * inRefCon,
AudioUnitRenderActionFlags * ioActionFlags,
const AudioTimeStamp * inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList * dummy_notused )
{
OSStatus status;
RemoteIOAudioUnit* unitClass = (RemoteIOAudioUnit *)inRefCon;
AudioComponentInstance myUnit = unitClass.myAudioUnit;
AudioBufferList ioData;
{
int kNumChannels = 1; // one channel...
enum {
kMono = 1,
kStereo = 2
};
ioData.mNumberBuffers = kNumChannels;
for (int i = 0; i < kNumChannels; i++)
{
int bytesNeeded = inNumberFrames * sizeof( Float32 );
ioData.mBuffers[i].mNumberChannels = kMono;
ioData.mBuffers[i].mDataByteSize = bytesNeeded;
ioData.mBuffers[i].mData = malloc( bytesNeeded );
}
}
// actually GET the data that arrived
status = AudioUnitRender( (void *)myUnit,
ioActionFlags,
inTimeStamp,
inBusNumber,
inNumberFrames,
& ioData );
// take MONO from mic
const int channel = 0;
Float32 * outBuffer = (Float32 *) ioData.mBuffers[channel].mData;
// get a handle to our game object
static KPRing* kpRing = nil;
if ( ! kpRing )
{
//AppDelegate * appDelegate = [UIApplication sharedApplication].delegate;
kpRing = [Game singleton].kpRing;
assert( kpRing );
}
// ... and send it the data we just got from the mic
[ kpRing floatsArrivedFromMic: outBuffer
count: inNumberFrames ];
return status;
}
inRefCon
指针传递预先分配的缓冲区。 - j b