Question

I´m trying to make a library for iPhone, so I´m trying to init the camera just with a call.
The problem comes when I call “self” in this declaration:

"[captureOutput setSampleBufferDelegate:self queue:queue];"

because the compiler says:” self was not declared in this scope”, what Do I need to do to set the same class as a “AVCaptureVideoDataOutputSampleBufferDelegate”?. At least point me in the right direction :P.

Thank you !!!

here is the complete function:

bool VideoCamera_Init(){


    //Init Capute from the camera and show the camera


    /*We setup the input*/
    AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput 
                                          deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] 
                                          error:nil];
    /*We setupt the output*/
    AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init];
    /*While a frame is processes in -captureOutput:didOutputSampleBuffer:fromConnection: delegate methods no other frames are added in the queue.
     If you don't want this behaviour set the property to NO */
    captureOutput.alwaysDiscardsLateVideoFrames = YES; 
    /*We specify a minimum duration for each frame (play with this settings to avoid having too many frames waiting
     in the queue because it can cause memory issues). It is similar to the inverse of the maximum framerate.
     In this example we set a min frame duration of 1/10 seconds so a maximum framerate of 10fps. We say that
     we are not able to process more than 10 frames per second.*/
    captureOutput.minFrameDuration = CMTimeMake(1, 20);

    /*We create a serial queue to handle the processing of our frames*/
    dispatch_queue_t queue;
    queue = dispatch_queue_create("cameraQueue", NULL);
    variableconnombrealeatorio= [[VideoCameraThread alloc] init];
    [captureOutput setSampleBufferDelegate:self queue:queue];


    dispatch_release(queue);
    // Set the video output to store frame in BGRA (It is supposed to be faster)
    NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey; 
    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]; 
    NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key]; 
    [captureOutput setVideoSettings:videoSettings]; 
    /*And we create a capture session*/
    AVCaptureSession * captureSession = [[AVCaptureSession alloc] init];
    captureSession.sessionPreset= AVCaptureSessionPresetMedium;
    /*We add input and output*/
    [captureSession addInput:captureInput];
    [captureSession addOutput:captureOutput];
    /*We start the capture*/
    [captureSession startRunning];


    return TRUE;
}

I also did the next class, but the buffer is empty:

“

#import “VideoCameraThread.h”

CMSampleBufferRef bufferCamara;

@implementation VideoCameraThread

• (void)captureOutput:(AVCaptureOutput *)captureOutput
  didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
  fromConnection:(AVCaptureConnection *)connection
  {
  bufferCamera=sampleBuffer;

  }
  “

Answer 1

You are writing a C function, which has no concept of Objective C classes, objects or the self identifier. You will need to modify your function to take a parameter to accept the sampleBufferDelegate that you want to use:

bool VideoCamera_Init(id<AVCaptureAudioDataOutputSampleBufferDelegate> sampleBufferDelegate) {
    ...
    [captureOutput setSampleBufferDelegate:sampleBufferDelegate queue:queue];
    ...
}

Or you could write your library with an Objective C object-oriented interface rather than a C-style interface.

You also have problems with memory management in this function. For instance, you are allocating an AVCaptureSession and assigning it to a local variable. After this function returns you will have no way of retrieving that AVCaptureSession so that you can release it.