CoreAudio实现录音播音和扬声器听筒模式的切换

本例子使用Core Audio实现类似于微信的音频对讲功能，可以录音和播放并且实现了听筒模式和扬声器模式的切换。录音主要使用AVAudioRecorder类来实现录音功能，播放则使用AVAudioPlayer类来实现播放音频功能，扬声器和听筒模式的切换是通过设置AVAudioSession类的属性值来实现切换效果。

- (void)viewDidLoad 

{ 

    [super viewDidLoad]; 

    //创建录音按钮 

    UIButton* recorderB = [[[UIButton alloc]initWithFrame:CGRectMake(20, 220, 60, 40)]autorelease]; 

    [recorderB setTitle:@"record" forState:UIControlStateNormal]; 

    [recorderB setBackgroundColor:[UIColor grayColor]]; 

    [recorderB addTarget:self action:@selector(prerecord:) forControlEvents:UIControlEventTouchDown]; 

    [recorderB addTarget:self action:@selector(startrecord:) forControlEvents:UIControlEventTouchUpInside]; 

    [self.view addSubview:recorderB]; 

     

    //创建播放按钮 

    UIButton* play = [[[UIButton alloc]initWithFrame:CGRectMake(230, 220, 60, 40)]autorelease]; 

    [play setTitle:@"play" forState:UIControlStateNormal]; 

    [play setBackgroundColor:[UIColor grayColor]]; 

    [play addTarget:self action:@selector(play:) forControlEvents:UIControlEventTouchUpInside]; 

    [self.view addSubview:play]; 

     

    //创建听筒模式和扬声器模式切换按钮 

    change = [[[UISwitch alloc]initWithFrame:CGRectMake(120, 225, 40, 40)]autorelease]; 

    //默认设置为没有打开，则用听筒模式 

    [change setOn:NO]; 

    [change addTarget:self action:@selector(change:) forControlEvents:UIControlEventValueChanged]; 

    [self.view addSubview:change]; 

     

} 

//切换按钮事件 

-(void)change:(UISwitch*)sender{ 

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    AVAudioSession *audioSession = [AVAudioSession sharedInstance]; 

    if ([sender isOn]) { 

        //设置下扬声器模式 

        [audioSession setCategory:AVAudioSessionCategoryPlayback error:nil]; 

         

    }else{ 

        //设置听筒模式 

        [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:nil]; 

    } 

    [audioSession setActive:YES error:nil]; 

} 

//录音事件 

-(void)record:(id)sender{ 

        //获取当前应用的AudioSession,每个应用都有自己唯一的声频会话 

        AVAudioSession * audioSession = [AVAudioSession sharedInstance]; 

        NSError* error1; 

         //设置当前应用的声频会话为录音模式 

        /* 

        Use this category for background sounds such as rain, car engine noise, etc. 

         Mixes with other music. 

          

         AVF_EXPORT NSString *const AVAudioSessionCategoryAmbient; 

          

         Use this category for background sounds.  Other music will stop playing.     AVF_EXPORT NSString *const AVAudioSessionCategorySoloAmbient; 

          

         Use this category for music tracks. 

          

         AVF_EXPORT NSString *const AVAudioSessionCategoryPlayback; 

          

         Use this category when recording audio. 

          

         AVF_EXPORT NSString *const AVAudioSessionCategoryRecord; 

          

         Use this category when recording and playing back audio. 

          

         AVF_EXPORT NSString *const AVAudioSessionCategoryPlayAndRecord; 

          

         Use this category when using a hardware codec or signal processor while 

         not playing or recording audio. 

          

         AVF_EXPORT NSString *const AVAudioSessionCategoryAudioProcessing; 

         */ 

        [audioSession setCategory:AVAudioSessionCategoryRecord error: &error1];

        //激活音频会话 

        [audioSession setActive:YES error: &error1]; 

        NSLog(@"record..."); 

        //创建录音的文件保存位置 

        NSString* filepath = [DOCUMENT_PATH stringByAppendingPathComponent:@"test.caf"]; 

        url = [[NSURL fileURLWithPath:filepath]retain]; 

        NSLog(@"path:%@",filepath); 

        //设置录音的相关属性 

        NSMutableDictionary *settings = [[NSMutableDictionary alloc] init]; 

        //设置音频格式 

        [settings 

         setValue:[NSNumber numberWithInteger:kAudioFormatLinearPCM] forKey:AVFormatIDKey]; 

        //设置采用率 

        [settings 

         setValue:[NSNumber numberWithFloat:44100.0f] forKey:AVSampleRateKey]; 

        //设置频道 

        [settings 

         setValue:[NSNumber numberWithInteger:2] forKey:AVNumberOfChannelsKey]; 

        //设置录音质量 

        [settings 

         setValue:[NSNumber numberWithInteger:AVAudioQualityHigh] forKey:AVEncoderAudioQualityKey]; 

        NSError* error; 

        recorder = [[AVAudioRecorder alloc]initWithURL:url settings:settings error:&error]; 

        recorder.delegate = self; 

        //录音准备，会为建立录音文件做好需要的准备 

        BOOL isrecord = [recorder prepareToRecord]; 

        NSLog(@"isrecord:%d",isrecord); 

        //正式开始录音 

        [recorder record]; 

        NSLog(@"record begin..."); 

     

} 
//手指离开点击录音按钮的事件 

-(void)startrecord:(id)sender{ 

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    NSTimeInterval now = [[NSDate date]timeIntervalSince1970]; 

    //获取长按录音按钮的时间 

    NSTimeInterval offset = now - starttime; 

    NSLog(@"offset:%f",offset); 

    //如果长按的时间少于1秒，则不录音 

    if (offset<=1) { 

        [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(record:) object:self]; 

    }else{ 

        //超过一秒，则完成录音，停止继续录音 

        [self stoprecorder:recorder]; 

    } 

} 
//手指点击录音按钮时间 

-(void)prerecord:(id)sender{ 

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    //获取点击的时间 

    starttime = [[NSDate date]timeIntervalSince1970]; 

    NSLog(@"starttime:%f",starttime); 

    //点击超过一秒后才正式录音 

    [self performSelector:@selector(record:) withObject:self afterDelay:1]; 

} 

//停止录音的事件 

-(void)stoprecorder:(AVAudioRecorder*)sender{ 

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    //判断是否还在录音，如果是就停止 

    if ([recorder isRecording]) { 

        [recorder stop]; 

    } 

    

} 
//播放事件 

-(void)play:(id)sender{ 

    

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    NSError* error; 

    NSLog(@"url:%@",url); 

    //通过AVAudioPlayer打开刚才录音的文件 

    AVAudioPlayer* player = [[AVAudioPlayer alloc]initWithData:[NSData dataWithContentsOfURL:url] error:&error]; 

    //AVAudioPlayer预处理，为需要播放做好准备 

    BOOL isplay = [player prepareToPlay]; 

    NSLog(@"isplay:%d",isplay); 

  //  player.volume = 1; 

    player.delegate = self; 

    //正式播放 

    [player play]; 

} 

- (void)didReceiveMemoryWarning 

{ 

     

    [super didReceiveMemoryWarning]; 

    // Dispose of any resources that can be recreated. 

} 
//录音完成后的回调事件 

- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag{ 

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    //录音完成后关闭释放资源 

    if ([recorder isRecording]) { 

        [recorder stop]; 

    } 

    [recorder release]; 

    //录音的时候因为设置的音频会话是录音模式，所以录音完成后要把音频会话设置回听筒模式或者扬声器模式，根据切换器的值判断 

    AVAudioSession *audioSession = [AVAudioSession sharedInstance]; 

    if ([change isOn]) { 

        //扬声器模式 

        [audioSession setCategory:AVAudioSessionCategoryPlayback error:nil]; 

         

    }else{ 

        //听筒模式 

        [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:nil]; 

    } 

    [audioSession setActive:YES error:nil]; 

     

} 

//录音编码出错的回调 

- (void)audioRecorderEncodeErrorDidOccur:(AVAudioRecorder *)recorder error:(NSError *)error{ 

    NSLog(@"%@",NSStringFromSelector(_cmd)); 

    [recorder release]; 

} 
//播放音频完成后的回调 

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag{ 

     NSLog(@"%@",NSStringFromSelector(_cmd)); 

    //成功播放完音频后释放资源 

    if ([player isPlaying]) { 

        [player stop]; 

    } 

    [player release]; 

} 

//音频播放解码出错的回调 

- (void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error{ 

 NSLog(@"%@",NSStringFromSelector(_cmd)); 

    [player release]; 

}