show_video_v4l_capture.c

一个可以进行视频采集和显示的源代码,在LINUX操作系统下使用,可通过修改移植到ARM.

/*==========================================================================
  $Id$
  show_video_v4l_capture.c: Functions for capturing video using V4L.
  Written by Naoyuki Ichimura, AIST, 2001.
==========================================================================*/

#include "show_video_v4l.h"
#include "extract_skin_color.h"

#define PREFIX_IMAGE_FILE 	"video_image"	

/*=== Local global variables ===*/
static unsigned char disp_image[IMAGE_WIDTH_DS*IMAGE_HEIGHT_DS*RGB];/* pointer to image buffer */

static int fd;			/* file descriptor for frame buffer */
static int exit_flag;		/* flag to exit program */
static int frame_no=1;		/* frame number */

static struct video_mbuf vm; 	/* structure for frame buffer */
static struct video_mmap vmap;	/* structure for memory space for frame buffer */

/*=== global variable ===*/
extern int extract_skin_color;	/* global variable for enabling image processing */

void ShowVideoCaptureImage()
{

    static char image_prefix[1024]=PREFIX_IMAGE_FILE;			/* Prefix of output image file */
    static unsigned char image[IMAGE_WIDTH_DS*IMAGE_HEIGHT_DS*RGB];	/* Captured image */
    static unsigned char skin_map[IMAGE_WIDTH_DS*IMAGE_HEIGHT_DS];	/* Skin color map */

/*======= Wait capture for current frame ====================*/
    CaptureV4LDoubleBufferingCaptureWait( fd , &vmap );

/*======= Set data to image array ===========================*/
    CaptureV4LSetImageDownSamplingForOpenGL( vmap , vm , DOWN_SAMPLING_RATE , image , disp_image );

/*======= Begin capture for next frame ======================*/
    if( CaptureV4LDoubleBufferingCaptureNextFrame( fd , &vmap ) == -1 ) {
	fprintf( stderr , "COuld not capture next frame.\n" );
	exit(-1);
    }

/*======= Display image =====================================*/
    ShowVideoDisplayImage();

/*======= Extract skin color by simple thresholding =========*/
    if( extract_skin_color ) {
	ExtractSkinColorSimpleThresholding( image , IMAGE_HEIGHT_DS , IMAGE_WIDTH_DS , skin_map );
	ShowSkinRegion( skin_map , IMAGE_HEIGHT_DS , IMAGE_WIDTH_DS );
    }

#if 0
/*======= Save image ========================================*/
    ShowVideoSavePPMImage( image , IMAGE_HEIGHT_DS , IMAGE_WIDTH_DS , frame_no , image_prefix );
#endif

/*======= Swap Buffer: show graphics ========================*/
    glutSwapBuffers();

/*======= Increment frame number ============================*/
    frame_no++;

/*======= Check exit flag ===================================*/
    if( exit_flag ) {
	exit(0);
    }

}

int ShowVideoInitCaptureDevice( char *device_name , int channel_no )
{

    struct video_capability vcap;		/* structure for video capability */
    struct video_channel vch[MAX_NO_CHANNEL]; 	/* structure for video channel */ 
    struct video_picture vp;

/*======= Open video device ================================*/
    if( ( fd = CaptureV4LOpen( device_name ) ) == -1 ) {
	fprintf( stderr, "Could not open device %s.\n" , device_name );
	exit(-1);
    }

/*======= Get information of device =========================*/
    /*=== Get device capabilities ===*/
    if( CaptureV4LGetDeviceCapability( fd , &vcap ) == -1 ) {
	fprintf( stderr , "Could not get capabilities of video device.\n" );
	exit(-1);
    }

    /*=== Get channel information ===*/
    if( CaptureV4LGetChannelInfo( fd , vch , vcap.channels ) == -1 ) {
	fprintf( stderr , "Could not get channel information of video device.\n" );
	exit(-1);
    }

    /*=== Get memory map information ===*/
    if( CaptureV4LGetMemoryMapInfo( fd , &vm ) == -1 ) {
	fprintf( stderr , "Could not get memory map information.\n" );
	exit(-1);
    }

/*======= Show picture information =========================*/
    CaptureV4LGetPictureInfo( fd , &vp );
    CaptureV4LDisplayPictureInfo( vp );

/*======= Select channel ===================================*/
    if( CaptureV4LSelectChannel( fd , vch , channel_no ) == -1 ) {
	fprintf( stderr , "Could not select channel.\n" );
	exit(-1);
    }

/*======= Mapping frame buffer ==============================*/
    if( CaptureV4LMemoryMapping( fd , vm ) == -1 ) {
	fprintf( stdout , "Could not map frame buffer.\n" );
	exit(-1);
    }

/*======= Set image size and formate ========================*/
    vmap.width = CAPTURE_IMAGE_WIDTH;
    vmap.height = CAPTURE_IMAGE_HEIGHT;
    vmap.format = VIDEO_PALETTE_RGB24;
    
/*======= Begin Capture =====================================*/
    CaptureV4LDoubleBufferingInitCapture( fd , &vmap );

    return 0;

}

void ShowVideoDisplayImage()
{

    glRasterPos2i( 0 , 0 );
    glDrawPixels( IMAGE_WIDTH_DS , IMAGE_HEIGHT_DS , GL_BGR , GL_UNSIGNED_BYTE , disp_image );
    glFlush();

}

void ShowVideoMouseCheck( int button , int status , int x , int y )
{

    if( button == GLUT_LEFT_BUTTON && status == GLUT_DOWN ) {
	exit_flag = 1;
    }

}

void ShowVideoSavePPMImage( unsigned char *image , int iheight , int iwidth , int frame_no , char *image_prefix )
{

    char file_name[1024];

    FILE *fp;

    sprintf( file_name , "%s_%d.ppm" , image_prefix , frame_no );
    if( ( fp = fopen( file_name , "w" ) ) == NULL ) {
	fprintf( stderr , "Could not open image file: %s\n" , file_name );
	exit(1);
    }
    fprintf( fp , "P6 %d %d 255\n" , iwidth , iheight );
    fwrite( image , iheight*iwidth*RGB , 1 , fp );
    fclose(fp);

}