iOS VoIP 应用程序 |音频队列 | AVSession 类别

Posted 2023-03-09

【中文标题】iOS VoIP 应用程序 |音频队列 | AVSession 类别

【英文标题】：iOS Voip Application | AudioQueue | AVSession Category

【发布时间】：2014-06-04 12:47:47

【问题描述】：

在我的 ios 应用程序中，我使用 AudioQueue 进行音频录制和播放，基本上我在 iOS 上运行并移植了 OSX 版本。 我意识到在 iOS 中我需要配置/设置 AV 会话，到目前为止我已经完成了以下操作，

-(void)initAudioSession

    //get your app's audioSession singleton object

    AVAudioSession* session = [AVAudioSession sharedInstance];

    //error handling
    BOOL success;
    NSError* error;

    //set the audioSession category.
    //Needs to be Record or PlayAndRecord to use audioRouteOverride:

    success = [session setCategory:AVAudioSessionCategoryPlayAndRecord
                             error:&error];

    if (!success)  NSLog(@"AVAudioSession error setting category:%@",error);

    //set the audioSession override
    success = [session overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker
                                         error:&error];
    if (!success)  NSLog(@"AVAudioSession error overrideOutputAudioPort:%@",error);

    //activate the audio session
    success = [session setActive:YES error:&error];
    if (!success) NSLog(@"AVAudioSession error activating: %@",error);
    else NSLog(@"audioSession active");

现在发生的事情是，Speaker AudioQueue 回调永远不会被调用，我检查了很多答案，cmets on so ，google 等...看起来是正确的，我做的方式是

为输入和输出创建音频队列：配置线性 PCM，16000 采样率 分配缓冲区 使用有效回调设置队列， 开始队列，

似乎很好，我可以听到另一端的输出（即 Input AudioQueue 正在工作）但输出 AudioQueue（即 AudioQueueOutputCallback 永远不会被调用）。

我怀疑我需要设置正确的 AVSessionCatogery，我正在尝试使用所有可能的选项，但无法在扬声器中听到任何声音，

我将我的实现与在主线程上运行 AudioQueue 的 Apple 示例 Speakhere 进行比较。 即使我不启动 Input AudioQueue ( mic )，我也会有同样的行为。并且很难有 Speakhere 行为，即停止录制和播放

感谢您的关注，期待您的 cmets/帮助。就能分享代码sn -p。

【参考方案1】：

感谢查看，我意识到了问题，这是我的回调，

void AudioStream::AQBufferCallback(void *                   inUserData,
                                   AudioQueueRef            inAQ,
                                   AudioQueueBufferRef      inCompleteAQBuffer)

    AudioStream *THIS = (AudioStream *)inUserData;
    if (THIS->mIsDone) 
        return;
    

    if ( !THIS->IsRunning())
        NSLog(@" AudioQueue is not running");
        **return;** // Error part 

    


    int bytes = THIS->bufferByteSize;       
    if ( !THIS->pSingleBuffer)
        THIS->pSingleBuffer = new unsigned char[bytes];
    
    unsigned char *buffer = THIS->pSingleBuffer;



    if ((THIS->mNumPacketsToRead) > 0) 
        /* lets read only firt packet */
        memset(buffer,0x00,bytes);


        float volume = THIS->volume();

        if (THIS->volumeChange)
            SInt16 *editBuffer = (SInt16 *)buffer;

            // loop over every packet

            for (int nb = 0; nb < (sizeof(buffer) / 2); nb++) 

                // we check if the gain has been modified to save resoures
                if (volume != 0) 
                    // we need more accuracy in our calculation so we calculate with doubles
                    double gainSample = ((double)editBuffer[nb]) / 32767.0;

                    /*
                     at this point we multiply with our gain factor
                     we dont make a addition to prevent generation of sound where no sound is.

                     no noise
                     0*10=0

                     noise if zero
                     0+10=10
                     */
                    gainSample *= volume;

                    /**
                     our signal range cant be higher or lesser -1.0/1.0
                     we prevent that the signal got outside our range
                     */
                    gainSample = (gainSample < -1.0) ? -1.0 : (gainSample > 1.0) ? 1.0 : gainSample;

                    /*
                     This thing here is a little helper to shape our incoming wave.
                     The sound gets pretty warm and better and the noise is reduced a lot.
                     Feel free to outcomment this line and here again.

                     You can see here what happens here http://silentmatt.com/javascript-function-plotter/
                     Copy this to the command line and hit enter: plot y=(1.5*x)-0.5*x*x*x
                     */

                    gainSample = (1.5 * gainSample) - 0.5 * gainSample * gainSample * gainSample;

                    // multiply the new signal back to short
                    gainSample = gainSample * 32767.0;

                    // write calculate sample back to the buffer
                    editBuffer[nb] = (SInt16)gainSample;
                
            
        
        else
            //            NSLog(@" No change in the volume");
        


        memcpy(inCompleteAQBuffer->mAudioData, buffer, 640);

        inCompleteAQBuffer->mAudioDataByteSize = 640;
        inCompleteAQBuffer->mPacketDescriptionCount = 320;
        show_err(AudioQueueEnqueueBuffer(inAQ, inCompleteAQBuffer, 0, NULL));
    

因为我在分配时没有入队，并且我相信它必须在开始之前将几个缓冲区入队，删除返回部分解决了我的问题。