AVFoundation，如何在captureStillImageAsynchronouslyFromConnection时关闭快门声音？

8 回答

• 2

  我使用此代码一次捕获iOS默认快门声音（这里是声音文件名列表https://github.com/TUNER88/iOSSystemSoundsLibrary）：

  NSString *path = @"/System/Library/Audio/UISounds/photoShutter.caf";
  NSString *docs = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
  NSData *data = [NSData dataWithContentsOfFile:path];
  [data writeToFile:[docs stringByAppendingPathComponent:@"photoShutter.caf"] atomically:YES];
  

  然后我使用第三方应用程序从Documents目录（DiskAid for Mac）中提取 photoShutter.caf . 下一步我在Audacity音频编辑器中打开 photoShutter.caf 并应用了反转效果，它在高变焦时看起来像这样：

  

  然后我把这个声音保存为 photoShutter2.caf 并试图在 captureStillImageAsynchronouslyFromConnection 之前播放这个声音：

  static SystemSoundID soundID = 0;
  if (soundID == 0) {
      NSString *path = [[NSBundle mainBundle] pathForResource:@"photoShutter2" ofType:@"caf"];
      NSURL *filePath = [NSURL fileURLWithPath:path isDirectory:NO];
      AudioServicesCreateSystemSoundID((__bridge CFURLRef)filePath, &soundID);
  }
  AudioServicesPlaySystemSound(soundID);
  
  [self.stillImageOutput captureStillImageAsynchronouslyFromConnection:
  ...
  

  这确实有效！每次听到没有快门声时我都会跑几次测试:)

  您可以通过以下链接获取已在iPhone 5S iOS 7.1.1上捕获的已反转声音：https://www.dropbox.com/s/1echsi6ivbb85bv/photoShutter2.caf

  回复于 2024-05-15T11:13:56+08:00
• 2

  Method 1: 不确定这是否有效，但在发送捕获事件之前尝试播放空白音频文件 .

  要播放剪辑，请在拍摄前立即添加 Audio Toolbox 框架， #include <AudioToolbox/AudioToolbox.h> 并播放如下所示的音频文件：

  NSString *path = [[NSBundle mainBundle] pathForResource:@"blank" ofType:@"wav"];
   SystemSoundID soundID;
   NSURL *filePath = [NSURL fileURLWithPath:path isDirectory:NO];
   AudioServicesCreateSystemSoundID((CFURLRef)filePath, &soundID);
   AudioServicesPlaySystemSound(soundID);
  

  如果需要，这是一个空白的音频文件 . http://cl.ly/3cKi

  ________________________________________________________________________________________________________________________________________

  Method 2: 有's also an alternative if this doesn'工作 . 只要你不需要一个好的分辨率，你就可以grab a frame from the video stream，从而完全避免画面声音 .

  ________________________________________________________________________________________________________________________________________

  Method 3: 另一种方法是使用"screenshot"的应用程序 . 这样做：

  UIGraphicsBeginImageContext(self.window.bounds.size);
  [self.window.layer renderInContext:UIGraphicsGetCurrentContext()];
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  NSData * data = UIImagePNGRepresentation(image);
  [data writeToFile:@"foo.png" atomically:YES];
  

  如果您希望通过预览视频流来填充整个屏幕，以便您的屏幕截图看起来很好：

  AVCaptureSession *captureSession = yourcapturesession;
  AVCaptureVideoPreviewLayer *previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];
  UIView *aView = theViewYouWantTheLayerIn;
  previewLayer.frame = aView.bounds; // Assume you want the preview layer to fill the view.
  [aView.layer addSublayer:previewLayer];
  

  回复于 2024-05-15T11:13:56+08:00
• 19

  我可以通过在snapStillImage函数中使用此代码来实现此功能，并且它在iOS 8.3 iPhone 5上完美适用于我 . 我还确认，如果您使用此功能，Apple将不会拒绝您的应用程序（他们不会拒绝矿）

  MPVolumeView* volumeView = [[MPVolumeView alloc] init];
  //find the volumeSlider
  UISlider* volumeViewSlider = nil;
  for (UIView *view in [volumeView subviews]){
      if ([view.class.description isEqualToString:@"MPVolumeSlider"]){
          volumeViewSlider = (UISlider*)view;
          break;
      }
  }
  // mute it here:
  [volumeViewSlider setValue:0.0f animated:YES];
  [volumeViewSlider sendActionsForControlEvents:UIControlEventTouchUpInside];
  

  当你的应用程序返回时，请记住保持良好并取消静音！

  回复于 2024-05-15T11:13:56+08:00
• 6

  我住在日本，因此出于安全原因我拍摄照片时无法将音频静音 . 在视频中，音频会关闭 . 我不明白为什么 .

  我拍摄没有快门声的照片的唯一方法是使用AVCaptureVideoDataOutput或AVCaptureMovieFileOutput . 对于分析静止图像AVCaptureVideoDataOutput是唯一的方法 . 在AVFoundatation示例代码中，

  AVCaptureVideoDataOutput *output = [[[AVCaptureVideoDataOutput alloc] init] autorelease];
  // If you wish to cap the frame rate to a known value, such as 15 fps, set 
  // minFrameDuration.
  output.minFrameDuration = CMTimeMake(1, 15);
  

  在我的3GS中，当我设置CMTimeMake（1,1）时它非常重; //每秒一帧

  在WWDC 2010示例代码FindMyiCone中，我找到了以下代码，

  [output setAlwaysDiscardsLateVideoFrames:YES];
  

  使用此API时，不会授予计时，但会按顺序调用API . 我这是最好的解决方案 .

  回复于 2024-05-15T11:13:56+08:00
• 0

  您还可以从视频流中获取帧以捕获（非全分辨率）图像 .

  使用here以短间隔捕获图像：

  - (IBAction)startStopPictureSequence:(id)sender
  {
      if (!_capturingSequence)
      {
          if (!_captureVideoDataOutput)
          {
              _captureVideoDataOutput = [AVCaptureVideoDataOutput new];
              _captureVideoDataOutput.videoSettings = @{(NSString *)kCVPixelBufferPixelFormatTypeKey: @(kCVPixelFormatType_32BGRA)};
              [_captureVideoDataOutput setSampleBufferDelegate:self
                                                         queue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0)];
              if (_sequenceCaptureInterval == 0)
              {
                  _sequenceCaptureInterval = 0.25;
              }
          }
  
          if ([_captureSession canAddOutput:_captureVideoDataOutput])
          {
              [_captureSession addOutput:_captureVideoDataOutput];
              _lastSequenceCaptureDate = [NSDate date]; // Skip the first image which looks to dark for some reason
              _sequenceCaptureOrientation = (_currentDevice.position == AVCaptureDevicePositionFront ? // Set the output orientation only once per sequence
                                             UIImageOrientationLeftMirrored :
                                             UIImageOrientationRight);
              _capturingSequence = YES;
          }
          else
          {
              NBULogError(@"Can't capture picture sequences here!");
              return;
          }
      }
      else
      {
          [_captureSession removeOutput:_captureVideoDataOutput];
          _capturingSequence = NO;
      }
  }
  
  - (void)captureOutput:(AVCaptureOutput *)captureOutput
  didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
         fromConnection:(AVCaptureConnection *)connection
  {
      // Skip capture?
      if ([[NSDate date] timeIntervalSinceDate:_lastSequenceCaptureDate] < _sequenceCaptureInterval)
          return;
  
      _lastSequenceCaptureDate = [NSDate date];
  
      UIImage * image = [self imageFromSampleBuffer:sampleBuffer];
      NBULogInfo(@"Captured image: %@ of size: %@ orientation: %@",
                 image, NSStringFromCGSize(image.size), @(image.imageOrientation));
  
      // Execute capture block
      dispatch_async(dispatch_get_main_queue(), ^
                     {
                         if (_captureResultBlock) _captureResultBlock(image, nil);
                     });
  }
  
  - (BOOL)isRecording
  {
      return _captureMovieOutput.recording;
  }
  

  回复于 2024-05-15T11:13:56+08:00
• 1486

  有关其他类型的答案，请参阅此文章：从图像缓冲区中捕获图像 . Screen capture during video preview fails

  回复于 2024-05-15T11:13:56+08:00
• 0

  我能想到的唯一可能的解决方法是在按下“拍照”按钮时静音iphone声音，然后在一秒钟之后取消静音 .

  回复于 2024-05-15T11:13:56+08:00
• 4

  在这种情况下，一个常见的技巧是找出框架是否为此事件调用某种方法，然后暂时覆盖该方法，从而消除其影响 .

  我很抱歉，但如果在这种情况下有效，我就不会立即告诉你 . 您可以在框架可执行文件上尝试“nm”命令，看看是否有一个具有适合名称的命名函数，或者使用gdb与Simulator一起跟踪它的去向 .

  一旦你知道要覆盖什么，我相信有一些低级别的ObjC调度函数可以用来重定向函数的查找 . 我想我刚刚做过这件事，但不记得细节了 .

  希望您可以使用我的提示谷歌一些解决方案路径 . 祝好运 .

  回复于 2024-05-15T11:13:56+08:00