同时 AVCaptureVideoDataOutput 和 AVCaptureMovieFileOutput

Question

我需要能够同时让AVCaptureVideoDataOutput 和AVCaptureMovieFileOutput 工作。以下代码有效，但是，视频录制无效。在调用startRecordingToOutputFileURL 之后直接调用didFinishRecordingToOutputFileAtURL 委托。现在，如果我从 AVCaptureSession 只需注释掉该行：

[captureSession addOutput:captureDataOutput];

视频录制有效，但未调用 SampleBufferDelegate（我需要）。

我怎样才能让AVCaptureVideoDataOutput 和AVCaptureMovieFileOutput 同时工作。

- (void)initCapture {
 AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] error:NULL]; 

 captureDataOutput = [[AVCaptureVideoDataOutput alloc] init]; 
 [captureDataOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()]; 

 m_captureFileOutput = [[AVCaptureMovieFileOutput alloc] init];

 NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey; 
 NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]; 
 NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key]; 

 [captureDataOutput setVideoSettings:videoSettings]; 

 captureSession = [[AVCaptureSession alloc] init]; 

 [captureSession addInput:captureInput];
 [captureSession addOutput:m_captureFileOutput]; 
 [captureSession addOutput:captureDataOutput]; 

 [captureSession beginConfiguration]; 
 [captureSession setSessionPreset:AVCaptureSessionPresetLow]; 
 [captureSession commitConfiguration]; 

 [self performSelector:@selector(startRecording) withObject:nil afterDelay:10.0];
 [self performSelector:@selector(stopRecording) withObject:nil afterDelay:15.0];

 [captureSession startRunning];
}


- (void) startRecording
{
    [m_captureFileOutput startRecordingToOutputFileURL:[self tempFileURL] recordingDelegate:self];

}

- (void) stopRecording
{
    if([m_captureFileOutput isRecording])
 [m_captureFileOutput stopRecording];

}


- (NSURL *) tempFileURL
{
 NSString *outputPath = [[NSString alloc] initWithFormat:@"%@%@", NSTemporaryDirectory(), @"camera.mov"];
 NSURL *outputURL = [[NSURL alloc] initFileURLWithPath:outputPath];
 NSFileManager *fileManager = [NSFileManager defaultManager];
 if ([fileManager fileExistsAtPath:outputPath]) {
  [[NSFileManager defaultManager] removeItemAtPath:outputPath error:nil];
 [outputPath release];
 return [outputURL autorelease];
}



- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections
{
 NSLog(@"start record video");
}

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
{
 NSLog(@"end record");
}


- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection 
{ 
      // do stuff with sampleBuffer
}

我应该补充一下，我收到了错误：

Error Domain=NSOSStatusErrorDomain Code=-12780 "The operation couldn’t be completed. (OSStatus error -12780.)" UserInfo=0x23fcd0 {AVErrorRecordingSuccessfullyFinishedKey=false}

来自

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error

干杯

Answer 1

9 年后，Apple 显然不希望这两者一起工作。

但您可以轻松地使用 AVAssetWriter。

您不能同时使用 AVCaptureVideoDataOutput 和 AVCaptureMovieFileOutput。但是您可以使用 AVCaptureVideoDataOutput 对数据进行分析或修改，然后使用 AVAsseWriter 将帧写入文件。

来源：https://developer.apple.com/forums/thread/98113

如何使用 AVAssetWriter 保存带有输出的视频：

Save AVCaptureVideoDataOutput to movie file using AVAssetWriter in Swift

Answer 2

我联系了 Apple 支持的工程师，他告诉我不支持同时使用 AVCaptureVideoDataOutput + AVCaptureMovieFileOutput。不知道他们以后会不会支持，但是他用了“暂时不支持”这个词。

我鼓励您像我一样 (bugreport.apple.com) 填写一份错误报告/功能请求，因为它们会衡量人们想要某样东西的难易程度，我们也许可以在不久的将来看到这一点。

Answer 3

虽然您不能使用AVCaptureVideoDataOutput，但您可以同时使用AVCaptureVideoPreviewLayer 和AVCaptureMovieFileOutput。请参阅 Apple 网站上的“AVCam”示例。

在 Xamarin.iOS 中，代码如下所示：

var session = new AVCaptureSession();

var camera = AVCaptureDevice.DefaultDeviceWithMediaType(AVMediaType.Video);
var  mic = AVCaptureDevice.DefaultDeviceWithMediaType(AVMediaType.Audio);
if(camera == null || mic == null){
    throw new Exception("Can't find devices");
}

if(session.CanAddInput(camera)){
    session.AddInput(camera);
}
if(session.CanAddInput(mic)){
   session.AddInput(mic);
}

var layer = new AVCaptureVideoPreviewLayer(session);
layer.LayerVideoGravity = AVLayerVideoGravity.ResizeAspectFill;
layer.VideoGravity = AVCaptureVideoPreviewLayer.GravityResizeAspectFill;

cameraView = new UIView();
cameraView.Layer.AddSublayer(layer);

var filePath = System.IO.Path.Combine( Path.GetTempPath(), "temporary.mov");
var fileUrl = NSUrl.FromFilename( filePath );

var movieFileOutput = new AVCaptureMovieFileOutput();
var recordingDelegate = new MyRecordingDelegate();
session.AddOutput(movieFileOutput);

movieFileOutput.StartRecordingToOutputFile( fileUrl, recordingDelegate);