我需要将音频从麦克风流式传输到 http 服务器。
这些录制设置是我需要的：
NSDictionary *audioOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt: kAudioFormatULaw],AVFormatIDKey,
[NSNumber numberWithFloat:8000.0],AVSampleRateKey,//was 44100.0
[NSData dataWithBytes: &acl length: sizeof( AudioChannelLayout ) ], AVChannelLayoutKey,
[NSNumber numberWithInt:1],AVNumberOfChannelsKey,
[NSNumber numberWithInt:64000],AVEncoderBitRateKey,
nil];
API im 编码到状态：
向当前查看的摄像机发送连续的音频流。音频需要以 64 kbit/s 的 G711 mu-law 编码，以便传输到床边的 Axis 摄像机。发送（这应该是 SSL 中的 POST URL 到连接的服务器）：POST /transmitaudio?id= Content-type: audio/basic Content-Length: 99999（长度被忽略）
以下是我尝试使用的链接列表。
LINK - （SO）基本解释，只有音频单元和音频队列才允许在通过麦克风录制时将 nsdata 作为输出 | 不是示例，而是对所需内容的良好定义（音频队列或音频单元）
LINK - (SO) 音频回调示例 | 只包括回调
LINK - (SO)REMOTE IO 示例 | 没有启动/停止，用于保存到文件
LINK - (SO)REMOTE IO 示例 | 未回答 不工作
LINK - (SO)基本录音示例 | 很好的例子，但要归档
链接- （SO）引导我进入 InMemoryAudioFile 类的问题（无法正常工作）| 跟随指向 inMemoryFile （或类似的东西）的链接，但无法让它工作。
LINK - (SO)more 音频单元和远程 io 示例/问题 | 让这个工作，但再次没有停止功能，即使我试图弄清楚呼叫是什么并让它停止，它似乎仍然没有将音频传输到服务器。
LINK - 不错的 remoteIO 和音频队列示例，但是 | 另一个很好的例子，几乎让它工作，但代码有一些问题（编译器认为它不是 obj-c++）并且再次不知道如何从它而不是文件中获取音频“数据”。
LINK - 用于音频队列的 Apple 文档 | 框架有问题。通过它（见下面的问题），但最终无法让它工作，但可能没有给这个时间和其他人一样多的时间，也许应该有。
LINK - (SO) 尝试实现音频队列/单元时遇到的问题 | 不是一个例子
LINK - (SO)另一个 remoteIO 示例 | 另一个很好的例子，但无法弄清楚如何将它获取到数据而不是文件。
LINK - 看起来也很有趣，循环缓冲区 | 无法弄清楚如何将其与音频回调结合起来
这是我目前正在尝试流式传输的课程。尽管接收器端（连接到服务器）的扬声器发出静电，但这似乎可行。这似乎表明音频数据格式存在问题。
IOS VERSION（减去 GCD 套接字的委托方法）：
@implementation MicCommunicator {
AVAssetWriter * assetWriter;
AVAssetWriterInput * assetWriterInput;
}
@synthesize captureSession = _captureSession;
@synthesize output = _output;
@synthesize restClient = _restClient;
@synthesize uploadAudio = _uploadAudio;
@synthesize outputPath = _outputPath;
@synthesize sendStream = _sendStream;
@synthesize receiveStream = _receiveStream;
@synthesize socket = _socket;
@synthesize isSocketConnected = _isSocketConnected;
-(id)init {
if ((self = [super init])) {
_receiveStream = [[NSStream alloc]init];
_sendStream = [[NSStream alloc]init];
_socket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
_isSocketConnected = FALSE;
_restClient = [RestClient sharedManager];
_uploadAudio = false;
NSArray *searchPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
_outputPath = [NSURL fileURLWithPath:[[searchPaths objectAtIndex:0] stringByAppendingPathComponent:@"micOutput.output"]];
NSError * assetError;
AudioChannelLayout acl;
bzero(&acl, sizeof(acl));
acl.mChannelLayoutTag = kAudioChannelLayoutTag_Mono; //kAudioChannelLayoutTag_Stereo;
NSDictionary *audioOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt: kAudioFormatULaw],AVFormatIDKey,
[NSNumber numberWithFloat:8000.0],AVSampleRateKey,//was 44100.0
[NSData dataWithBytes: &acl length: sizeof( AudioChannelLayout ) ], AVChannelLayoutKey,
[NSNumber numberWithInt:1],AVNumberOfChannelsKey,
[NSNumber numberWithInt:64000],AVEncoderBitRateKey,
nil];
assetWriterInput = [[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:audioOutputSettings]retain];
[assetWriterInput setExpectsMediaDataInRealTime:YES];
assetWriter = [[AVAssetWriter assetWriterWithURL:_outputPath fileType:AVFileTypeWAVE error:&assetError]retain]; //AVFileTypeAppleM4A
if (assetError) {
NSLog (@"error initing mic: %@", assetError);
return nil;
}
if ([assetWriter canAddInput:assetWriterInput]) {
[assetWriter addInput:assetWriterInput];
} else {
NSLog (@"can't add asset writer input...!");
return nil;
}
}
return self;
}
-(void)dealloc {
[_output release];
[_captureSession release];
[_captureSession release];
[assetWriter release];
[assetWriterInput release];
[super dealloc];
}
-(void)beginStreaming {
NSLog(@"avassetwrter class is %@",NSStringFromClass([assetWriter class]));
self.captureSession = [[AVCaptureSession alloc] init];
AVCaptureDevice *audioCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
NSError *error = nil;
AVCaptureDeviceInput *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioCaptureDevice error:&error];
if (audioInput)
[self.captureSession addInput:audioInput];
else {
NSLog(@"No audio input found.");
return;
}
self.output = [[AVCaptureAudioDataOutput alloc] init];
dispatch_queue_t outputQueue = dispatch_queue_create("micOutputDispatchQueue", NULL);
[self.output setSampleBufferDelegate:self queue:outputQueue];
dispatch_release(outputQueue);
self.uploadAudio = FALSE;
[self.captureSession addOutput:self.output];
[assetWriter startWriting];
[self.captureSession startRunning];
}
-(void)pauseStreaming
{
self.uploadAudio = FALSE;
}
-(void)resumeStreaming
{
self.uploadAudio = TRUE;
}
-(void)finishAudioWork
{
[self dealloc];
}
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
AudioBufferList audioBufferList;
NSMutableData *data= [[NSMutableData alloc] init];
CMBlockBufferRef blockBuffer;
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);
for (int y = 0; y < audioBufferList.mNumberBuffers; y++) {
AudioBuffer audioBuffer = audioBufferList.mBuffers[y];
Float32 *frame = (Float32*)audioBuffer.mData;
[data appendBytes:frame length:audioBuffer.mDataByteSize];
}
// append [data bytes] to your NSOutputStream
// These two lines write to disk, you may not need this, just providing an example
[assetWriter startSessionAtSourceTime:CMSampleBufferGetPresentationTimeStamp(sampleBuffer)];
[assetWriterInput appendSampleBuffer:sampleBuffer];
//start upload audio data
if (self.uploadAudio) {
if (!self.isSocketConnected) {
[self connect];
}
NSString *requestStr = [NSString stringWithFormat:@"POST /transmitaudio?id=%@ HTTP/1.0\r\n\r\n",self.restClient.sessionId];
NSData *requestData = [requestStr dataUsingEncoding:NSUTF8StringEncoding];
[self.socket writeData:requestData withTimeout:5 tag:0];
[self.socket writeData:data withTimeout:5 tag:0];
}
//stop upload audio data
CFRelease(blockBuffer);
blockBuffer=NULL;
[data release];
}
和 JAVA 版本：
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Arrays;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder.AudioSource;
import android.util.Log;
public class AudioWorker extends Thread
{
private boolean stopped = false;
private String host;
private int port;
private long id=0;
boolean run=true;
AudioRecord recorder;
//ulaw encoder stuff
private final static String TAG = "UlawEncoderInputStream";
private final static int MAX_ULAW = 8192;
private final static int SCALE_BITS = 16;
private InputStream mIn;
private int mMax = 0;
private final byte[] mBuf = new byte[1024];
private int mBufCount = 0; // should be 0 or 1
private final byte[] mOneByte = new byte[1];
////
/**
* Give the thread high priority so that it's not canceled unexpectedly, and start it
*/
public AudioWorker(String host, int port, long id)
{
this.host = host;
this.port = port;
this.id = id;
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);
// start();
}
@Override
public void run()
{
Log.i("AudioWorker", "Running AudioWorker Thread");
recorder = null;
AudioTrack track = null;
short[][] buffers = new short[256][160];
int ix = 0;
/*
* Initialize buffer to hold continuously recorded AudioWorker data, start recording, and start
* playback.
*/
try
{
int N = AudioRecord.getMinBufferSize(8000,AudioFormat.CHANNEL_IN_MONO,AudioFormat.ENCODING_PCM_16BIT);
recorder = new AudioRecord(AudioSource.MIC, 8000, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, N*10);
track = new AudioTrack(AudioManager.STREAM_MUSIC, 8000, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, N*10, AudioTrack.MODE_STREAM);
recorder.startRecording();
// track.play();
/*
* Loops until something outside of this thread stops it.
* Reads the data from the recorder and writes it to the AudioWorker track for playback.
*/
SSLContext sc = SSLContext.getInstance("SSL");
sc.init(null, trustAllCerts, new java.security.SecureRandom());
SSLSocketFactory sslFact = sc.getSocketFactory();
SSLSocket socket = (SSLSocket)sslFact.createSocket(host, port);
socket.setSoTimeout(10000);
InputStream inputStream = socket.getInputStream();
DataInputStream in = new DataInputStream(new BufferedInputStream(inputStream));
OutputStream outputStream = socket.getOutputStream();
DataOutputStream os = new DataOutputStream(new BufferedOutputStream(outputStream));
PrintWriter socketPrinter = new PrintWriter(os);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
// socketPrinter.println("POST /transmitaudio?patient=1333369798370 HTTP/1.0");
socketPrinter.println("POST /transmitaudio?id="+id+" HTTP/1.0");
socketPrinter.println("Content-Type: audio/basic");
socketPrinter.println("Content-Length: 99999");
socketPrinter.println("Connection: Keep-Alive");
socketPrinter.println("Cache-Control: no-cache");
socketPrinter.println();
socketPrinter.flush();
while(!stopped)
{
Log.i("Map", "Writing new data to buffer");
short[] buffer = buffers[ix++ % buffers.length];
N = recorder.read(buffer,0,buffer.length);
track.write(buffer, 0, buffer.length);
byte[] bytes2 = new byte[buffer.length * 2];
ByteBuffer.wrap(bytes2).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().put(buffer);
read(bytes2, 0, bytes2.length);
os.write(bytes2,0,bytes2.length);
//
// ByteBuffer byteBuf = ByteBuffer.allocate(2*N);
// System.out.println("byteBuf length "+2*N);
// int i = 0;
// while (buffer.length > i) {
// byteBuf.putShort(buffer[i]);
// i++;
// }
// byte[] b = new byte[byteBuf.remaining()];
}
os.close();
}
catch(Throwable x)
{
Log.w("AudioWorker", "Error reading voice AudioWorker", x);
}
/*
* Frees the thread's resources after the loop completes so that it can be run again
*/
finally
{
recorder.stop();
recorder.release();
track.stop();
track.release();
}
}
/**
* Called from outside of the thread in order to stop the recording/playback loop
*/
public void close()
{
stopped = true;
}
public void resumeThread()
{
stopped = false;
run();
}
TrustManager[] trustAllCerts = new TrustManager[]{
new X509TrustManager() {
public java.security.cert.X509Certificate[] getAcceptedIssuers() {
return null;
}
public void checkClientTrusted(
java.security.cert.X509Certificate[] certs, String authType) {
}
public void checkServerTrusted(
java.security.cert.X509Certificate[] chain, String authType) {
for (int j=0; j<chain.length; j++)
{
System.out.println("Client certificate information:");
System.out.println(" Subject DN: " + chain[j].getSubjectDN());
System.out.println(" Issuer DN: " + chain[j].getIssuerDN());
System.out.println(" Serial number: " + chain[j].getSerialNumber());
System.out.println("");
}
}
}
};
public static void encode(byte[] pcmBuf, int pcmOffset,
byte[] ulawBuf, int ulawOffset, int length, int max) {
// from 'ulaw' in wikipedia
// +8191 to +8159 0x80
// +8158 to +4063 in 16 intervals of 256 0x80 + interval number
// +4062 to +2015 in 16 intervals of 128 0x90 + interval number
// +2014 to +991 in 16 intervals of 64 0xA0 + interval number
// +990 to +479 in 16 intervals of 32 0xB0 + interval number
// +478 to +223 in 16 intervals of 16 0xC0 + interval number
// +222 to +95 in 16 intervals of 8 0xD0 + interval number
// +94 to +31 in 16 intervals of 4 0xE0 + interval number
// +30 to +1 in 15 intervals of 2 0xF0 + interval number
// 0 0xFF
// -1 0x7F
// -31 to -2 in 15 intervals of 2 0x70 + interval number
// -95 to -32 in 16 intervals of 4 0x60 + interval number
// -223 to -96 in 16 intervals of 8 0x50 + interval number
// -479 to -224 in 16 intervals of 16 0x40 + interval number
// -991 to -480 in 16 intervals of 32 0x30 + interval number
// -2015 to -992 in 16 intervals of 64 0x20 + interval number
// -4063 to -2016 in 16 intervals of 128 0x10 + interval number
// -8159 to -4064 in 16 intervals of 256 0x00 + interval number
// -8192 to -8160 0x00
// set scale factors
if (max <= 0) max = MAX_ULAW;
int coef = MAX_ULAW * (1 << SCALE_BITS) / max;
for (int i = 0; i < length; i++) {
int pcm = (0xff & pcmBuf[pcmOffset++]) + (pcmBuf[pcmOffset++] << 8);
pcm = (pcm * coef) >> SCALE_BITS;
int ulaw;
if (pcm >= 0) {
ulaw = pcm <= 0 ? 0xff :
pcm <= 30 ? 0xf0 + (( 30 - pcm) >> 1) :
pcm <= 94 ? 0xe0 + (( 94 - pcm) >> 2) :
pcm <= 222 ? 0xd0 + (( 222 - pcm) >> 3) :
pcm <= 478 ? 0xc0 + (( 478 - pcm) >> 4) :
pcm <= 990 ? 0xb0 + (( 990 - pcm) >> 5) :
pcm <= 2014 ? 0xa0 + ((2014 - pcm) >> 6) :
pcm <= 4062 ? 0x90 + ((4062 - pcm) >> 7) :
pcm <= 8158 ? 0x80 + ((8158 - pcm) >> 8) :
0x80;
} else {
ulaw = -1 <= pcm ? 0x7f :
-31 <= pcm ? 0x70 + ((pcm - -31) >> 1) :
-95 <= pcm ? 0x60 + ((pcm - -95) >> 2) :
-223 <= pcm ? 0x50 + ((pcm - -223) >> 3) :
-479 <= pcm ? 0x40 + ((pcm - -479) >> 4) :
-991 <= pcm ? 0x30 + ((pcm - -991) >> 5) :
-2015 <= pcm ? 0x20 + ((pcm - -2015) >> 6) :
-4063 <= pcm ? 0x10 + ((pcm - -4063) >> 7) :
-8159 <= pcm ? 0x00 + ((pcm - -8159) >> 8) :
0x00;
}
ulawBuf[ulawOffset++] = (byte)ulaw;
}
}
public static int maxAbsPcm(byte[] pcmBuf, int offset, int length) {
int max = 0;
for (int i = 0; i < length; i++) {
int pcm = (0xff & pcmBuf[offset++]) + (pcmBuf[offset++] << 8);
if (pcm < 0) pcm = -pcm;
if (pcm > max) max = pcm;
}
return max;
}
public int read(byte[] buf, int offset, int length) throws IOException {
if (recorder == null) throw new IllegalStateException("not open");
// return at least one byte, but try to fill 'length'
while (mBufCount < 2) {
int n = recorder.read(mBuf, mBufCount, Math.min(length * 2, mBuf.length - mBufCount));
if (n == -1) return -1;
mBufCount += n;
}
// compand data
int n = Math.min(mBufCount / 2, length);
encode(mBuf, 0, buf, offset, n, mMax);
// move data to bottom of mBuf
mBufCount -= n * 2;
for (int i = 0; i < mBufCount; i++) mBuf[i] = mBuf[i + n * 2];
return n;
}
}