AuidioStreamPlayer简易实现

首先可以先从下面列出的参考中进行对整个Audio Stream进行一定程度的理解

参考：

https://github.com/muhku/FreeStreamer
https://github.com/mattgallagher/AudioStreamer
http://msching.github.io/blog/2014/07/09/audio-in-ios-3/
http://msching.github.io/blog/2014/08/02/audio-in-ios-5/

主要数据结构：

typedef struct AudioStream{    AudioFileStreamID                       mAudioFileStream;    AudioQueueRef                           mQueue;    AudioQueueBufferRef                     mBuffer[kNumbersOfBuffer];    AudioStreamPacketDescription            mPacketDecs[kMaxPacketDescs];    AudioStreamBasicDescription             mAudioStreamBasicDesc;    unsigned int                            mFillBufferIndex;    UInt32                                  mPacketBufferSize;    size_t                                  mBytesFilled;    size_t                                  mPacketsFilled;    bool                                    mInused[kNumbersOfBuffer];    NSInteger                               mBuffersUsed;}AS;typedef struct StreamFile{    UInt32                                  mBitRate;    NSInteger                               mFileLength;    NSInteger                               mDataOffset;    UInt64                                  mAudioDataByteCount;}SF;extern NSString * const ASStatusChangedNotification;@interface FileStreamPlayer : NSObject{    AS                                      audioStream;    BOOL                                    discontinuous;    NSThread                                *internalThread;    NSURL                                   *url;    NSDictionary                            *httpHeader;    NSString                                *fileExtension;    SF                                      streamFile;    double                                  sampleRate;    double                                  packetDuration;    CFReadStreamRef                         stream;    pthread_mutex_t                         queueBuffersMutex;    pthread_cond_t                          queueBufferReadyCondition;    AudioStreamState                        state;    AudioStreamStopReason                   stopReason;    NSNotificationCenter                    *notificationCenter;}

首先，要实现AudioStream的获取，通过CFNetWorking的库来发送HTTP请求，并通过建立客户端接受数据将数据加入到当前RunLoop中：

CFHTTPMessageRef message= CFHTTPMessageCreateRequest(NULL,                                                             (CFStringRef)@"GET",                                                             (CFURLRef)url,                                                             kCFHTTPVersion1_1);        stream = CFReadStreamCreateForHTTPRequest(NULL, message);        CFRelease(message);        CFDictionaryRef proxySettings = CFNetworkCopySystemProxySettings();        CFReadStreamSetProperty(stream, kCFStreamPropertyHTTPProxy, proxySettings);        CFRelease(proxySettings);        CFStreamClientContext context = {0, self, NULL, NULL, NULL};        CFReadStreamSetClient(                              stream,                              kCFStreamEventHasBytesAvailable |                              kCFStreamEventErrorOccurred |                              kCFStreamEventEndEncountered,                              ASReadStreamCallBack,                              &context);        CFReadStreamScheduleWithRunLoop(stream, CFRunLoopGetCurrent(), kCFRunLoopCommonModes);

这里会要求实现网络流数据获取后的回调函数：ReadStreamCallBack

static void ASReadStreamCallBack(CFReadStreamRef                aStream,                                 CFStreamEventType              eventType,                                 void*                          inClientInfo) {    FileStreamPlayer* this = (FileStreamPlayer *)inClientInfo;    [this handleReadFromStream:aStream eventType:eventType];}

函数参数中要求：当前数据流，流事件类型，以及上下文对象

成功读取数据以后，通过：AudioFileStreamOpen将数据打开，可以理解成AudioFile读取时候打开一个数据流，然后进行解析

    AudioFileStreamOpen    AudioFileStreamParseBytes

OpenStream中要求填入两个回调函数：PropertyListenerProc和ASPacketsProc，分别作为流信息和流解析分离帧的回调之后的分离帧解析中，每次都会回调刚刚填入的回调函数

static void ASPropertyListenerProc(//callback from audioStream header                                   void *                           inClientData,                                   AudioFileStreamID                inAudioFileStream,                                   AudioFileStreamPropertyID        inPropertyID,                                   UInt32 *                         ioFlags) {    FileStreamPlayer* this = (FileStreamPlayer *)inClientData;    [this handleFileStreamPropertyChange:inAudioFileStream                        fileStreamPropertyID:inPropertyID                                     ioFlags:ioFlags];}static void ASPacketsProc(//callback from audioStream body                          void *                            inClientData,                          UInt32                            inNumberBytes,                          UInt32                            inNumberPackets,                          const void *                      inInputData,                          AudioStreamPacketDescription      *inPacketDescriptions) {    FileStreamPlayer* this = (FileStreamPlayer *)inClientData;    [this handleAudioPackets:inInputData                 numberBytes:inNumberBytes               numberPackets:inNumberPackets          packetDescriptions:inPacketDescriptions];}

接下来的操作就是包括流信息解析后存入相应的数据结构中，利用Buffer存储塞到AudioQueue中去进行运行，设置相应的AudioQueue的回调函数对完成任务后的buffer进行再次调用：

AudioQueueNewOutput(&audioStream.mAudioStreamBasicDesc,                        ASAudioQueueOutputCallback,                        self, NULL, NULL, 0, &audioStream.mQueue);static void ASAudioQueueOutputCallback(//callBack from Running Queue Buffers completed                                       void*                    inClientData,                                       AudioQueueRef            inAQ,                                       AudioQueueBufferRef      inBuffer) {    FileStreamPlayer* this = (FileStreamPlayer*)inClientData;    [this handleCompleteBuffer:inAQ                        buffer:inBuffer];}

接下来就可以对AudioQueue进行各种操作了，播放暂停和停止等。另外，还要注意各个操作过程中线程资源之间的调用必须要用锁进行保护，在这里我主要参考了AudioStreamer，所以采用了互斥锁pthread_和@synchronized（self）。

最后，附上我的DEMO：

http://download.csdn.net/detail/atomic123/9323745