4. 概念和基本程序

      dc1394_setup_format7_capture(
  /* handle and camera_nodes[0] uniquely identifies the camera */
            handle,
            camera_nodes[0],
            channel, /* channel */
            mode , /*mode */
            bytes_per_packet , 
            left ,/*area of interest start column */
            right, /*area of interest start row */
            width,/* area of interest width */
            height /* area of interest height */
           &camera /* dc1394_cameracapture type pointer *./
            )!=DC1394_SUCCESS) 

#include <stdio.h>
#include <libraw1394/raw1394.h>
#include <libdc1394/dc1394_control.h>
#include <stdlib.h>  
#include <iostream>
#define IMAGE_FILE_NAME "Image.pgm"
using namespace std;

int main(int arc, char *argv[]){
        FILE * imagefile;
        dc1394_cameracapture camera;
        int numNodes;
        int numCameras;
        raw1394handle_t handle;
        nodeid_t * camera_nodes;
        unsigned int channel, speed, format, framerate, mode;
        
        /*Step 1: Open ohci and assign a handle to it.*/
	/*=======================================================*/
	handle = dc1394_create_handle(0);
        if(handle==NULL){
                fprintf(stderr, "Unable to acquire a handle. \n\n");
        }
        else{
		 cout <<"dma1394: Handle aquired successfully-" <<handle<<"\n";
        }
        
/*Step 2: Get the camera nodes and describe them as we find them.*/
	/*=========================================================================*/
	numNodes = raw1394_get_nodecount(handle);
        camera_nodes = dc1394_get_camera_nodes(handle, &numCameras, 1);
        fflush(stdout);
        if (numCameras<1){
                fprintf(stderr, "No cameras found :( \n");
                dc1394_destroy_handle(handle);
                return -1;
        }
        else{
                cout<<"dma1394:"<< numCameras<<" cameras found. \n";
        }
        printf("dma1394: Working with the first camera on the bus.\n");
        if(camera_nodes[0] == numNodes-1){
                fprintf(stderr, "\n" "dma1394: Sorry, your camera is the highest numbered node.\n");
                dc1394_destroy_handle(handle);
                dc1394_free_camera_nodes(camera_nodes);
                return -1;
        }
        
/*Step 3: Setup Capture*/
	/*=====================================================================*/
	/*Using camera functions to get the params by querying them*/
	cout<<"INFO FOR DEBUG: \n"
                        "num_dma_buffers: "<< camera.num_dma_buffers<<"\n";
        dc1394_get_iso_channel_and_speed(handle, camera_nodes[0], &channel, &speed); /*get channel and speed*/
	dc1394_get_video_format(handle, camera_nodes[0], &format); /*get format*/
	dc1394_get_video_framerate(handle, camera_nodes[0], &framerate); /*get framerate*/
	dc1394_get_video_mode(handle, camera_nodes[0], &mode); /*get mode*/
	cout<<"dc1394: Got parameters from the camera.\n"
                "=======================================\n"
                "Channel: "<< channel<< " \n"
                "Speed: " <<speed <<" \n"
                "Format: "<< format <<" \n"
                "Framerate: " <<framerate<< "\n"
                "Mode: "<< mode <<"\n";
        camera.num_dma_buffers = 8; /* set the dma buffers */
        camera.drop_frames = 1; /* set the number of drop frames */
        camera.dma_device_file = NULL;
        if(dc1394_dma_setup_capture(handle, camera_nodes[0], channel, format, mode, speed, framerate, camera.num_dma_buffers, camera.drop_frames, camera.dma_device_file, &camera) !=DC1394_SUCCESS){
                fprintf(stderr, "dma1394: Unable to setup camera.\n" 
                                        "Check line %d of %s to ensure that the options set are supported by your camera.\n", __LINE__, __FILE__);
                dc1394_destroy_handle(handle);
                dc1394_free_camera_nodes(camera_nodes);
                return -1;
        }
        else{
                printf("dma1394: Capture has been setup.\n");
        }
        dc1394_free_camera_nodes(camera_nodes);

        //Set Trigger Mode -- Generally not required thus I will comment it out.
	/*if(dc1394_set_trigger_mode(handle, camera.node, TRIGGER_MODE_0) != DC1394_SUCCESS){
                fprintf(stderr, "dma1394: Unable to set the camera trigger mode. Refer to line %d in %s.\n", __LINE__, __FILE__);
                dc1394_release_camera(handle, &camera);
                dc1394_destroy_handle(handle);
        }
        else{
                printf("dma1394: Successfully set trigger mode.\n");
        }*/
        
        /*Step 4: Start sending data */
	/*=======================================================*/
	if(dc1394_start_iso_transmission(handle, camera.node) != DC1394_SUCCESS){
                fprintf(stderr, "dma1394: Unable to start the data transmission.\n");
                dc1394_dma_done_with_buffer(&camera);
				dc1394_dma_release_camera(handle, &camera);
                dc1394_destroy_handle(handle);
                return -1;
        }
        else{
                printf("dma1394: Success.  Data Transmission started.\n");
        }
        
        /*Step 5: Capture Something...Anything...PLEASE*/
	/*===============================================================*/
	if(dc1394_dma_single_capture(&camera) != DC1394_SUCCESS){
                fprintf(stderr, "dma1394; DAIM, can't capture a single frame.\n");
				dc1394_dma_done_with_buffer(&camera); /*important step */
                dc1394_dma_release_camera(handle, &camera);
                dc1394_destroy_handle(handle);
                return -1;
        }
        else{
                printf("dma1394: GREAT SUCCESS! Captured a single frame.\n");
        }
        
        /*Step 6: Stop sending data*/
	/*==================================================*/
	if(dc1394_dma_unlisten(handle, &camera) != DC1394_SUCCESS){
        		fprintf(stderr, "Can't unlisten iso channel! \n");
        }
        else{
                printf("dma1394: DMA unlistened. \n");
        }
        
	if(dc1394_stop_iso_transmission(handle, camera.node) != DC1394_SUCCESS){
                fprintf(stderr, " Can't stop the camera!! \n");
        }
        else{
                printf("dma1394: Data transmission terminated. \n");
        }
        
        /*Step 7: Save our image*/
	/*===============================================================*/
	imagefile=fopen(IMAGE_FILE_NAME, "w");
        if(imagefile==NULL){
                perror("dma1394: Can't create' "IMAGE_FILE_NAME" ' ");
                dc1394_dma_done_with_buffer(&camera);
				dc1394_dma_release_camera(handle, &camera);
                dc1394_destroy_handle(handle);
                return -1;
        }
        else{
                cout<<"dma1394: Saved image in "<<IMAGE_FILE_NAME<<".\n";
        }
         /*Add pgm file header*/
	fprintf(imagefile, "P5\n%u %u 255\n", camera.frame_width, camera.frame_height);
       
		/*write to file*/
	fwrite((const char *)camera.capture_buffer, 1, camera.frame_height*camera.frame_width, imagefile);
        fclose(imagefile);
        printf("dma1394: wrote: " IMAGE_FILE_NAME "\n");
        
        /*Step 8: Close camera*/
	/*=============================================================*/
	dc1394_dma_done_with_buffer(&camera);
	dc1394_dma_release_camera(handle, &camera);
        dc1394_destroy_handle(handle);
        printf("dma1394: Camera released.  Exiting. \n");
        
        //Step END
	return 0;

}