使用OpenAL播放硬件设备采集的PCM音频数据

1.几个用到的结构体FRAMEINFO

typedef struct _FRAMEINFO
{
 unsigned short codec_id; // Media codec type defined in sys_mmdef.h,
        // MEDIA_CODEC_AUDIO_PCMLE16 for audio,双声道音频数据         PCM16LE:16代表采样位数为16bit,LE:Little Endian
                               
 //介绍PCM采样数据的网站: http://www.jianshu.com/p/43fd50f0a8ba
        
// MEDIA_CODEC_VIDEO_H264 for video.
 unsigned char flags;  // Combined with IPC_FRAME_xxx.
 unsigned char cam_index; // 0 - n

 unsigned char onlineNum; // number of client connected this device 连接到这个设备的客户端数量
 unsigned char reserve1[3];

 unsigned int reserve2; //
 unsigned int timestamp; // Timestamp of the frame, in milliseconds 每一帧的时间戳,精确到毫秒级

    // unsigned int videoWidth; 没有用到
    // unsigned int videoHeight;也没有用到
    
}FRAMEINFO_t;

- (void)doRecvAudio
{
    //NSLog(@"=== RecvAudio Thread Start (%@) ===", uid);
    OpenALPlayer *player = nil;
    BOOL bFirst = YES;
    
    int readSize = 0;
    char recvBuf[RECV_AUDIO_BUFFER_SIZE] = {0};
       
    FRAMEINFO_t stFrmInfo = {0};
    
    unsigned int nFrmNo = 0;
    
    short decodeBuffer[640];
    unsigned char outBuffer[1280];
    
    if (sessionID >= 0 && avIndex >= 0)
    {
        avClientCleanAudioBuf(avIndex);
    }
    
    while(isRunningRecvAudioThread)
    {
    
        if (sessionID >= 0 && avIndex >= 0)
        {
    
            readSize = avRecvAudioData(avIndex, recvBuf, RECV_AUDIO_BUFFER_SIZE, (char *)&stFrmInfo, sizeof(FRAMEINFO_t), &nFrmNo);
     
            if (readSize >= 0)
            {
                                
                if (bFirst)
                {
                    bFirst = NO;
                    player = [[OpenALPlayer alloc] init];
                    [player  initOpenAL:AL_FORMAT_MONO16 :8000];
                    
                }   
                //printf("Receive Audio------------------------>>>%d %X:\n\n",readSize,stFrmInfo.codec_id);
                //16进制0x8F 0x8A
                if ((stFrmInfo.codec_id == 0x8F)||(stFrmInfo.codec_id == 0x8A))
                {

                    memset(decodeBuffer, 0, sizeof(decodeBuffer));
                    
                    G711Decoder(decodeBuffer,(unsigned char *)recvBuf,readSize,0);
                    
                    memset(outBuffer, 0, sizeof(outBuffer));
                    memcpy(outBuffer, (unsigned char*)decodeBuffer, readSize*2);

                    //录音
                    [[Mp4VideoRecorder getInstance] writeListenData:(unsigned char*)outBuffer withSize:readSize*2];
                        
                    [player openAudioFromQueue:outBuffer withLength:readSize*2];

                }

                
            }
            else if (readSize == AV_ER_DATA_NOREADY) {                
                //NSLog(@"avRecvAudioData return AV_ER_DATA_NOREADY");
                usleep(10 * 1000);
            }
            else if (readSize == AV_ER_LOSED_THIS_FRAME)
            {
                //NSLog(@"avRecvAudioData return AV_ER_LOSED_THIS_FRAME");
            }
            else
            {
                //NSLog(@"avRecvAudioData return err - %d", readSize);
                usleep(10 * 1000);
            }
        }
        else usleep(10 * 1000);
    }

    if (player != nil)
    {
        [player stopSound];
        [player cleanUpOpenAL];
        [player release];
        player = nil;
    }
    
    NSLog(@"=== Recv Audio Thread Exit (%@) ===",self.name);
    
}