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AVCaptureSessionは、キャプチャされた画像の解像度と品質を指定しますobj-ciphoneアプリ

こんにちは私はAVキャプチャセッションをセットアップして、iphoneカメラを使用して特定の解像度で（可能であれば特定の品質で）画像をキャプチャしたいと思います。 AVセッションコードの設定は次のとおりです

// Create and configure a capture session and start it running
- (void)setupCaptureSession 
{
    NSError *error = nil;

    // Create the session
    self.captureSession = [[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.
    captureSession.sessionPreset = AVCaptureSessionPresetMedium;

    // Find a suitable AVCaptureDevice
    NSArray *cameras=[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    AVCaptureDevice *device;
    if ([UserDefaults camera]==UIImagePickerControllerCameraDeviceFront)
    {
        device =[cameras objectAtIndex:1];
    }
    else
    {
        device = [cameras objectAtIndex:0];
    };

    // Create a device input with the device and add it to the session.
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input)
    {
        NSLog(@"PANIC: no media input");
    }
    [captureSession addInput:input];

    // Create a VideoDataOutput and add it to the session
    AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
    [captureSession addOutput:output];
    NSLog(@"connections: %@", output.connections);

    // 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];


    // If you wish to cap the frame rate to a known value, such as 15 fps, set 
    // minFrameDuration.


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

およびsetSession：

-(void)setSession:(AVCaptureSession *)session
{
    NSLog(@"setting session...");
    self.captureSession=session;
    NSLog(@"setting camera view");
    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
    //UIView *aView = self.view;
    CGRect videoRect = CGRectMake(20.0, 20.0, 280.0, 255.0);
    previewLayer.frame = videoRect; // Assume you want the preview layer to fill the view.
    [previewLayer setBackgroundColor:[[UIColor grayColor] CGColor]];
    [self.view.layer addSublayer:previewLayer];
    //[aView.layer addSublayer:previewLayer];
}

および出力方法：

// Delegate routine that is called when a sample buffer was written
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
   fromConnection:(AVCaptureConnection *)connection
{ 
    //NSLog(@"captureOutput: didOutputSampleBufferFromConnection");

    // Create a UIImage from the sample buffer data
    self.currentImage = [self imageFromSampleBuffer:sampleBuffer];

    //< Add your code here that uses the image >
}

// Create a UIImage from sample buffer data
- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer 
{
    //NSLog(@"imageFromSampleBuffer: called");
    // Get a CMSampleBuffer's Core Video image buffer for the media data
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
    // Lock the base address of the pixel buffer
    CVPixelBufferLockBaseAddress(imageBuffer, 0); 

    // Get the number of bytes per row for the pixel buffer
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); 

    // Get the number of bytes per row for the pixel buffer
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
    // Get the pixel buffer width and height
    size_t width = CVPixelBufferGetWidth(imageBuffer); 
    size_t height = CVPixelBufferGetHeight(imageBuffer); 

    // Create a device-dependent RGB color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 

    // Create a bitmap graphics context with the sample buffer data
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 
    // Create a Quartz image from the pixel data in the bitmap graphics context
    CGImageRef quartzImage = CGBitmapContextCreateImage(context); 
    // Unlock the pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);


    // Free up the context and color space
    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace);

    // Create an image object from the Quartz image
    UIImage *image = [UIImage imageWithCGImage:quartzImage];

    // Release the Quartz image
    CGImageRelease(quartzImage);

    return (image);
}

すべてが非常に標準的です。ただし、キャプチャした画像の解像度と品質を指定するには、どこで何を変更すればよいですか。お願い助けて

iphoneobjective-cavcapturesessionavcapture
13
Oleg

いずれかのプリセットを設定した場合に得られるサイズについては、 Appleのガイド 静止画像のキャプチャのセクションを参照してください。

変更する必要のあるパラメーターはcaptureSession.sessionPreset

13
Eugene

Cxとcyがカスタム解像度である次のようなものを試してください：

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                              AVVideoScalingModeResizeAspectFill,AVVideoScalingModeKey,
                           AVVideoCodecH264, AVVideoCodecKey,
                           [NSNumber numberWithInt:cx], AVVideoWidthKey,
                           [NSNumber numberWithInt:cx], AVVideoHeightKey,
                           nil];
_videoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
0
Catalin