在录制音频片段时设置时间限制？

Question

我根据帖子的标题查找了搜索词，但是..

我正在使用AVFoundation构建一个iPhone应用程序。

是否有一个正确的程序来限制将要录制的音频数量？我想最多10秒钟。

感谢您的帮助/建议/提示/提示。

Answer 1

AVAudioRecorder有以下方法：

- (BOOL)recordForDuration:(NSTimeInterval)duration

我想这样就行了！

http://developer.apple.com/library/ios/#documentation/AVFoundation/Reference/AVAudioRecorder_ClassReference/Reference/Reference.html#//apple_ref/doc/uid/TP40008238

Answer 2

我通常不使用AVFoundation，所以我不知道确切的方法/类名称(我填写了自己的名称)，但解决这个问题的一个办法是在最初开始录制时使用一个循环的NSTimer。如下所示：

@interface blahblah
...
int rec_time;
NSTimer *timer;
Recorder *recorder;
...
@end

@implementation blahblah
...
-(void)beginRecording {
    [recorder startRecording];
    timer = [NSTimer scheduledTimerWithTimeInterval:1.0
    target:self
    selector:@selector(recordingTime)
    userInfo:nil
    repeats:YES];
}

-(int)recordingTime {
    if (rec_time >= 10) {
        [recorder endRecording];
        [timer invalidate];
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"You recorded for too long!"...;
        return;
    }

    rec_time = rec_time + 1;

}
...
@end

Answer 3

这是iOS编程指南中的一个例子，我发现它非常有用和简单。开始录制后，调用延迟为10秒的停止函数，停止录制时会自动调用委托方法audioRecorderDidFinishRecording:successfully。

@implementation ViewController{

   AVAudioRecorder *recorder;
   AVAudioPlayer *player;
}   

- (IBAction)recordPauseTapped:(id)sender {
// Stop the audio player before recording
   if (player.playing) {
     [player stop];
   }

   if (!recorder.recording) {
      AVAudioSession *session = [AVAudioSession sharedInstance];
      [session setActive:YES error:nil];

      // Start recording
      [recorder record];

     [recordPauseButton setBackgroundImage:recordingImage forState:UIControlStateNormal];
     [self performSelector:@selector(stopRecording)
               withObject:self afterDelay:10.0f];

     } else {
       [recorder stop];

       AVAudioSession *audioSession = [AVAudioSession sharedInstance];
       [audioSession setActive:NO error:nil];
     }
} 

- (void)stopRecording {
  [recorder stop];

  AVAudioSession *audioSession = [AVAudioSession sharedInstance];
  [audioSession setActive:NO error:nil];
}

 - (void) audioRecorderDidFinishRecording:(AVAudioRecorder *)avrecorder    successfully:(BOOL)flag{
    NSLog(@"after 10 sec");
}