Question

我有这个应用程序的记录视频，我需要每次抓取一个帧时触发一个方法。在我的头撞到墙上之后，我决定尝试以下操作：创建一个调度队列，因为我会从输出中获取一个视频，只是为了在摄像机记录帧时调用一个方法。

我正在尝试了解Apple创建的一段代码，用于录制视频以了解我应该如何添加调度队列。这是苹果代码，星号之间标记的部分是我添加的部分，以便创建队列。它编译时没有错误，但 captureOutput：didOutputSampleBuffer：fromConnection：永远不会被调用。

- (BOOL) setupSessionWithPreset:(NSString *)sessionPreset error:(NSError **)error
{
    BOOL success = NO;

    // Init the device inputs
    AVCaptureDeviceInput *videoInput = [[[AVCaptureDeviceInput alloc] initWithDevice:[self backFacingCamera] error:error] autorelease];
    [self setVideoInput:videoInput]; // stash this for later use if we need to switch cameras

    AVCaptureDeviceInput *audioInput = [[[AVCaptureDeviceInput alloc] initWithDevice:[self audioDevice] error:error] autorelease];
    [self setAudioInput:audioInput];

    AVCaptureMovieFileOutput *movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
    [self setMovieFileOutput:movieFileOutput];
    [movieFileOutput release];


    // Setup and start the capture session
    AVCaptureSession *session = [[AVCaptureSession alloc] init];

    if ([session canAddInput:videoInput]) {
        [session addInput:videoInput];
    }
    if ([session canAddInput:audioInput]) {
        [session addInput:audioInput];
    }
    if ([session canAddOutput:movieFileOutput]) {
        [session addOutput:movieFileOutput];
    }

    [session setSessionPreset:sessionPreset];


    //  I added this *****************
    dispatch_queue_t queue = dispatch_queue_create("myqueue", NULL);
    [[self videoDataOutput] setSampleBufferDelegate:self queue:queue];
    dispatch_release(queue);
    // ******************** end of my code      

    [session startRunning];
    [self setSession:session];
    [session release];
    success = YES;
    return success;
}

我需要的只是一种可以处理正在记录的每一帧的方法。

感谢

Answer 1

将自己设为代表后，您将收到以下电话：

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

每次捕获新帧时。你可以在那里放置你想要的任何代码 - 只是要小心，因为你不会在主线程上。在[target performSelectorOnMainThread:@selector(methodYouActuallyWant)]中进行快速-captureOutput:didOutputSampleBuffer:fromConnection:可能是最安全的。

另外：我在我的代码中使用以下设置，并成功导致调用委托方法。我无法看到它与您正在使用的内容之间存在任何实质性差异。

- (id)initWithSessionPreset:(NSString *)sessionPreset delegate:(id <AAVideoSourceDelegate>)aDelegate
{

#ifndef TARGET_OS_EMBEDDED
    return nil;
#else

    if(self = [super init])
    {
        delegate = aDelegate;

        NSError *error = nil;

        // create a low-quality capture session
        session = [[AVCaptureSession alloc] init];
        session.sessionPreset = sessionPreset;

        // grab a suitable device...
        device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

        // ...and a device input
        AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

        if(!input || error)
        {
            [self release];
            return nil;
        }
        [session addInput:input];

        // create a VideDataOutput to route output to us
        AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
        [session addOutput:[output autorelease]];

        // create a suitable dispatch queue, GCD style, and hook self up as the delegate
        dispatch_queue_t queue = dispatch_queue_create("aQueue", NULL);
        [output setSampleBufferDelegate:self queue:queue];
        dispatch_release(queue);

        // set 32bpp BGRA pixel format, since I'll want to make sense of the frame
        output.videoSettings =
            [NSDictionary 
                dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
                forKey:(id)kCVPixelBufferPixelFormatTypeKey];

    }

    return self;
#endif
}

- (void)start
{
    [session startRunning];
}

- (void)stop
{
    [session stopRunning];
}

Answer 2

// create a suitable dispatch queue, GCD style, and hook self up as the delegate
        dispatch_queue_t queue = dispatch_queue_create("aQueue", NULL);
        [output setSampleBufferDelegate:self queue:queue];
        dispatch_release(queue);

也非常重要

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

一定要放一个

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];在开始时，最后一个[池排水]会在太多的过程后崩溃。

苹果手机。处理相机正在录制的帧

2 个答案:

苹果手机 。处理相机正在录制的帧

2 个答案:

苹果手机。处理相机正在录制的帧