cvvideo.cpp

guide and some example with visualC++

    pthread_mutex_init(&(camera->pausemutex), NULL);
    pthread_mutex_init(&(camera->capturestatemutex), NULL);
    pthread_cond_init(&(camera->capturestatecond), NULL);
    camera->capturestate          = FINISHED;
    camera->memorymap             = NULL;
    camera->renderstate           = 0;
    pthread_mutex_init(&(camera->updatedmutex), NULL);
    pthread_cond_init(&(camera->updatedcond), NULL);
    camera->updated               = 0;
    camera->videopp.picture.palette = VIDEO_PALETTE_RGB24;
    camera->imagepalette = VIDEO_PALETTE_RGB24;
    
    camera->description.maxwidth    = VidCap.maxwidth;
    
    camera->description.maxheight   = VidCap.maxheight;
    
    camera->description.minwidth    = VidCap.minwidth;

    if(camera->description.minwidth<160)
        camera->description.minwidth = 160;
    
    camera->description.minheight   = VidCap.minheight;
    
    if(camera->description.minheight<120)
        camera->description.minheight = 120;
    
    if(ioctl(device,VIDIOCGPICT,
        &(camera->videopp.picture) )==-1)
        return 0;   
    
    camera->videopp.picture.palette   = VIDEO_PALETTE_RGB24;
    camera->imagepalette = VIDEO_PALETTE_RGB24;
    camera->videopp.width             = camera->description.maxwidth;
    
    camera->videopp.height            = camera->description.maxheight;
    camera->videopp.picture.depth      = 24;
    camera->videopp.picture.brightness = 30000;
    camera->videopp.picture.hue        = 30000;
    camera->videopp.picture.colour     = 30000;
    camera->videopp.picture.contrast   = 30000;
    camera->videopp.picture.whiteness  = 30000;
    camera->callback                   = NULL;

    camera->renderwidth                = 0;
    camera->renderheight               = 0;
    
    if(ioctl(device,VIDIOCSPICT,
        &(camera->videopp.picture) )==-1)
    {
#ifdef DEBUG_CVCAM
        fprintf(stdout, "icvSetDefaultValues: ioctl VIDIOCSPICT failed, trying YUV420P format\n");
#endif
        camera->videopp.picture.palette   = VIDEO_PALETTE_YUV420P;
        if(ioctl(device,VIDIOCSPICT,
                 &(camera->videopp.picture) )==-1)
        {
            fprintf(stdout, "icvSetDefaultValues: ioctl VIDIOCSPICT failed even in YUV420P format\n");
#ifdef DEBUG_CVCAM
            fprintf(stdout,"camera=%d,brightness=%d,hue=%d,colour=%d,contrast=%d,whiteness=%d,depth=%d,palette=%d\n",
                    camera,
                    camera->videopp.picture.brightness,
                    camera->videopp.picture.hue,
                    camera->videopp.picture.colour,
                    camera->videopp.picture.contrast,
                    camera->videopp.picture.whiteness,
                    camera->videopp.picture.depth,
                    camera->videopp.picture.palette);
#endif
            return 0;
        }
    }
#ifdef DEBUG_CVCAM
    fprintf(stdout,"OK! camera=%d,brightness=%d,hue=%d,colour=%d,contrast=%d,whiteness=%d,depth=%d,palette=%d\n",
            camera,
                    camera->videopp.picture.brightness,
                    camera->videopp.picture.hue,
                    camera->videopp.picture.colour,
                    camera->videopp.picture.contrast,camera->videopp.picture.whiteness,camera->videopp.picture.depth,camera->videopp.picture.palette);
#endif
    return 1;
}

/**********************************************************************
 *
 * Color correction functions
 *
 **********************************************************************/

/*
 * Turn a YUV4:2:0 block into an RGB block
 *
 * Video4Linux seems to use the blue, green, red channel
 * order convention-- rgb[0] is blue, rgb[1] is green, rgb[2] is red.
 *
 * Color space conversion coefficients taken from the excellent
 * http://www.inforamp.net/~poynton/ColorFAQ.html
 * In his terminology, this is a CCIR 601.1 YCbCr -> RGB.
 * Y values are given for all 4 pixels, but the U (Pb)
 * and V (Pr) are assumed constant over the 2x2 block.
 *
 * To avoid floating point arithmetic, the color conversion
 * coefficients are scaled into 16.16 fixed-point integers.
 * They were determined as follows:
 *
 *	double brightness = 1.0;  (0->black; 1->full scale) 
 *	double saturation = 1.0;  (0->greyscale; 1->full color)
 *	double fixScale = brightness * 256 * 256;
 *	int rvScale = (int)(1.402 * saturation * fixScale);
 *	int guScale = (int)(-0.344136 * saturation * fixScale);
 *	int gvScale = (int)(-0.714136 * saturation * fixScale);
 *	int buScale = (int)(1.772 * saturation * fixScale);
 *	int yScale = (int)(fixScale);	
 */

/* LIMIT: convert a 16.16 fixed-point value to a byte, with clipping. */
#define LIMIT(x) ((x)>0xffffff?0xff: ((x)<=0xffff?0:((x)>>16)))

static inline void
move_420_block(int yTL, int yTR, int yBL, int yBR, int u, int v, 
	       int rowPixels, unsigned char * rgb, int bits)
{
	const int rvScale = 91881;
	const int guScale = -22553;
	const int gvScale = -46801;
	const int buScale = 116129;
	const int yScale  = 65536;
	int r, g, b;

	g = guScale * u + gvScale * v;
//	if (force_rgb) {
//		r = buScale * u;
//		b = rvScale * v;
//	} else {
		r = rvScale * v;
		b = buScale * u;
//	}

	yTL *= yScale; yTR *= yScale;
	yBL *= yScale; yBR *= yScale;

	if (bits == 24) {
		/* Write out top two pixels */
		rgb[0] = LIMIT(b+yTL); rgb[1] = LIMIT(g+yTL);
		rgb[2] = LIMIT(r+yTL);

		rgb[3] = LIMIT(b+yTR); rgb[4] = LIMIT(g+yTR);
		rgb[5] = LIMIT(r+yTR);

		/* Skip down to next line to write out bottom two pixels */
		rgb += 3 * rowPixels;
		rgb[0] = LIMIT(b+yBL); rgb[1] = LIMIT(g+yBL);
		rgb[2] = LIMIT(r+yBL);

		rgb[3] = LIMIT(b+yBR); rgb[4] = LIMIT(g+yBR);
		rgb[5] = LIMIT(r+yBR);
	} else if (bits == 16) {
		/* Write out top two pixels */
		rgb[0] = ((LIMIT(b+yTL) >> 3) & 0x1F) 
			| ((LIMIT(g+yTL) << 3) & 0xE0);
		rgb[1] = ((LIMIT(g+yTL) >> 5) & 0x07)
			| (LIMIT(r+yTL) & 0xF8);

		rgb[2] = ((LIMIT(b+yTR) >> 3) & 0x1F) 
			| ((LIMIT(g+yTR) << 3) & 0xE0);
		rgb[3] = ((LIMIT(g+yTR) >> 5) & 0x07) 
			| (LIMIT(r+yTR) & 0xF8);

		/* Skip down to next line to write out bottom two pixels */
		rgb += 2 * rowPixels;

		rgb[0] = ((LIMIT(b+yBL) >> 3) & 0x1F)
			| ((LIMIT(g+yBL) << 3) & 0xE0);
		rgb[1] = ((LIMIT(g+yBL) >> 5) & 0x07)
			| (LIMIT(r+yBL) & 0xF8);

		rgb[2] = ((LIMIT(b+yBR) >> 3) & 0x1F)
			| ((LIMIT(g+yBR) << 3) & 0xE0);
		rgb[3] = ((LIMIT(g+yBR) >> 5) & 0x07)
			| (LIMIT(r+yBR) & 0xF8);
	}
}

/* Converts from planar YUV420 to RGB24. */
static void 
yuv420p_to_rgb(int width, int height,
	       unsigned char *pIn0, unsigned char *pOut0, int bits)
{
	const int numpix = width * height;
	const int bytes = bits >> 3;
	int i, j, y00, y01, y10, y11, u, v;
	unsigned char *pY = pIn0;
	unsigned char *pU = pY + numpix;
	unsigned char *pV = pU + numpix / 4;
	unsigned char *pOut = pOut0;

	for (j = 0; j <= height - 2; j += 2) {
		for (i = 0; i <= width - 2; i += 2) {
			y00 = *pY;
			y01 = *(pY + 1);
			y10 = *(pY + width);
			y11 = *(pY + width + 1);
			u = (*pU++) - 128;
			v = (*pV++) - 128;

			move_420_block(y00, y01, y10, y11, u, v,
				       width, pOut, bits);
	
			pY += 2;
			pOut += 2 * bytes;

		}
		pY += width;
		pOut += width * bytes;
	}
}


// allocates a nes iplimage containing the last grabbed image.
// Can be called from the main thread or the render thread, via
//   GetProperty("raw_image"), or from the capturing thread, via
//   the callback
static IplImage *
icvVideoGetImage(int cameraid)
{
    CvSize size;
    CvVideoCamera *const camera = &(cameras[cameraid]);
    IplImage *image;
    void *data;
    int lastframe;
    int depth = icvVideoFormat2Depth(camera->imagepalette);

    pthread_mutex_lock(&(camera->capturestatemutex));
    if(!(camera->capturestate==CAPTURING))
    {
        pthread_mutex_unlock(&(camera->capturestatemutex));
        return NULL;
    }
    pthread_mutex_unlock(&(camera->capturestatemutex));
    size.width = camera->videopp.width;
    size.height = camera->videopp.height;
    
    assert(camera->videopp.picture.palette);
    assert(icvVideoFormat2Depth(camera->imagepalette));

    image = cvCreateImageHeader(size,IPL_DEPTH_8U,depth/8);
    pthread_mutex_lock(&(camera->lastframemutex));
    lastframe = camera->lastframe;
    pthread_mutex_unlock(&(camera->lastframemutex));
    pthread_rwlock_rdlock(&(camera->framelock[lastframe]));
    if (camera->imagepalette == camera->videopp.picture.palette)
    {
        IplImage *buffer = cvCreateImageHeader(size,IPL_DEPTH_8U,depth/8);
        cvSetImageData(buffer,
                       (void*)(camera->memorymap+
                       camera->mbuf.offsets[camera->lastframe]),
                       size.width*(depth/8));
        cvCreateImageData(image);
        cvCopyImage(buffer, image);
        pthread_rwlock_unlock(&(camera->framelock[lastframe]));
        cvReleaseImageHeader(&buffer);
        return image;
    }
    // only one conversion is implemented, for now
    assert(camera->videopp.picture.palette == VIDEO_PALETTE_YUV420P);
    assert((camera->imagepalette == VIDEO_PALETTE_RGB24) ||
           (camera->imagepalette == VIDEO_PALETTE_RGB565));
    
    data = (void*)cvAlloc(size.width*size.height*(depth/8));
    cvSetImageData(image, data, size.width*(depth/8));
    yuv420p_to_rgb(camera->videopp.width,
                   camera->videopp.height,
                   (unsigned char*)(camera->memorymap+
                   camera->mbuf.offsets[camera->lastframe]),
                   (unsigned char*)(data),
                   depth);
    pthread_rwlock_unlock(&(camera->framelock[lastframe]));
    return image;
}

//Stubs for avi files

/*Plays a specified avi file into a specified window
if file is NULL, file browser is opened. if window is 0,
it is created. width and height mean output size's 0 means
those of avi file are used. __cdecl (*callback)(IplImage*) would be
called on every frame. NULL means no callback*/
CVCAM_API int cvcamPlayAVI(const char* file,
                           void* window,
                           int width,
                           int height,
                           void* callback)
{

return -1;
}


/*Advanced API for dealing with AVI files*/




/*Opens a given file or pops up a dialog if file is NULL
returns a handle to the file opened for success or -1 for failure*/
CVCAM_API cvcamAVIFILE cvcamAVIOpenFile(char* file)
{
    return (cvcamAVIFILE)-1;
}

/*The next functions just do what they say and return 0
for success, anything other for failure*/

CVCAM_API int cvcamAVICloseFile(cvcamAVIFILE file)
{
    return -1;
}

CVCAM_API int cvcamAVISetWindow(cvcamAVIFILE file, void* window)
{
    return -1;
}

CVCAM_API int cvcamAVISetCallback(cvcamAVIFILE file, void* callback)
{
    return -1;
}

CVCAM_API int cvcamAVISetSize(cvcamAVIFILE file, int width, int height)
{
    return -1;
}

CVCAM_API int cvcamAVIRun(cvcamAVIFILE file)
{
    return -1;
}

CVCAM_API int cvcamAVIStop(cvcamAVIFILE file)
{
    return -1;
}

CVCAM_API int cvcamAVIPause(cvcamAVIFILE file)
{
    return -1;
}

CVCAM_API int cvcamAVIResume(cvcamAVIFILE file)
{
    return -1;
}

CVCAM_API int cvcamAVIWaitCompletion(cvcamAVIFILE file)
{
    return -1;
}

CVCAM_API int cvcamAVIIsRunning(cvcamAVIFILE file)
{
    return -1;
}