获取录制视频原始帧

Question

我是 Objective-C 和 iOS 技术的新手。我想通过代码录制视频，并且在运行时，我必须将每一帧作为原始数据进行一些处理。我该如何实现这个？请任何人帮助我。提前致谢。到目前为止，这是我的代码：

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self setupCaptureSession];

}

viewDidAppear 函数

-(void)viewDidAppear:(BOOL)animated
{
    if (!_bpickeropen)
    {
       _bpickeropen = true;
        _picker = [[UIImagePickerController alloc] init];
        _picker.delegate = self;
        NSArray *sourceTypes = [UIImagePickerController availableMediaTypesForSourceType:picker.sourceType];
        if (![sourceTypes containsObject:(NSString *)kUTTypeMovie ])
        {
            NSLog(@"device not supported");
            return;
        }

        _picker.sourceType = UIImagePickerControllerSourceTypeCamera;
        _picker.mediaTypes = [NSArray arrayWithObjects:(NSString *)kUTTypeMovie,nil];//,(NSString *) kUTTypeImage
        _picker.videoQuality = UIImagePickerControllerQualityTypeHigh;
        [self presentModalViewController:_picker animated:YES];
    }



}

// 写入样本缓冲区时调用的委托例程

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
       fromConnection:(AVCaptureConnection *)connection
{

    CVImageBufferRef cameraFrame = CMSampleBufferGetImageBuffer(sampleBuffer);


    CVPixelBufferLockBaseAddress(cameraFrame, 0);

    GLubyte *rawImageBytes = CVPixelBufferGetBaseAddress(cameraFrame);

    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(cameraFrame);

    **NSData *dataForRawBytes = [NSData dataWithBytes:rawImageBytes length:bytesPerRow * CVPixelBufferGetHeight(cameraFrame)];

**

问题 1.（这里我只得到一次原始字节） 2.（之后我想将此原始字节作为二进制文件存储在应用程序路径中）。

// Do whatever with your bytes

NSLog(@"bytes per row %zd",bytesPerRow);

[dataForRawBytes writeToFile:[self datafilepath]atomically:YES];

NSLog(@"Sample Buffer Data is %@\n",dataForRawBytes);


CVPixelBufferUnlockBaseAddress(cameraFrame, 0);

}

我在这里设置输出委托//创建和配置捕获会话并开始运行 - (void)setupCaptureSession { NSError *error = nil;

// Create the session
AVCaptureSession *session = [[AVCaptureSession alloc] init];


// Configure the session to produce lower resolution video frames, if your
// processing algorithm can cope. We'll specify medium quality for the
// chosen device.
session.sessionPreset = AVCaptureSessionPresetMedium;

// Find a suitable AVCaptureDevice
AVCaptureDevice *device = [AVCaptureDevice
                           defaultDeviceWithMediaType:AVMediaTypeVideo];

// Create a device input with the device and add it to the session.
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device
                                                                    error:&error];
if (!input)
{
    // Handling the error appropriately.
}
[session addInput:input];

// Create a VideoDataOutput and add it to the session
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
[session addOutput:output];


// Configure your output.
dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];
dispatch_release(queue);

// Specify the pixel format
output.videoSettings =
[NSDictionary dictionaryWithObject:
 [NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
                            forKey:(id)kCVPixelBufferPixelFormatTypeKey]; //kCVPixelBufferPixelFormatTypeKey


// If you wish to cap the frame rate to a known value, such as 15 fps, set
// minFrameDuration.
// output.minFrameDuration = CMTimeMake(1, 15);

// Start the session running to start the flow of data
[session startRunning];

// Assign session to an ivar.
//[self setSession:session];

}

感谢您的帮助。提前致谢。

Answer 1

您可以查看AVFoundation 框架。它允许您访问从相机生成的原始数据。

这个link 是一个很好的 AVFoundation 摄像机使用入门级项目。

为了从视频输出中获取单个帧，您可以使用 AVFoundation 框架中的 AVCaptureVideoDataOutput 类。

希望这会有所帮助。

编辑：您可以查看AVCaptureVideoDataOutputSampleBufferDelegate 的委托函数，特别是captureOutput:didOutputSampleBuffer:fromConnection: 方法。每次捕获新帧时都会调用它。

如果您不知道委托是如何工作的，这个link 就是一个很好的委托示例。