2、執行流程：

(1)開啟裝置：cameraOpen()

(2)裝置初始化：cameraInit()

(3)建立記憶體對映：mmapInit()

(4)開始視訊採集並捕獲影象資料：captureStart()

(5)迴圈採集：mainLoop()

(6)讀取資料：frameRead()

(7)資料處理：imageProcess()

3、常見錯誤及解決方法：

(1) No capture device info

VIDIOC_REQBUFS error 19, No such device

這個錯誤糾結了很久很久，在網上搜了很久，在群裡問了很多人，都沒解決，最後求助出售此試驗箱裝置公司的工程師，他也沒給出原因，只是給了我一個可以執行的例程，我就自己對照了下，然後除錯，查出來，原因在與，沒有設定

二、儲存jpg圖片程式：

1、原始碼：jpg.c

1. /*
2. * jpg.c
3. *
4. */
5. #include "classroom.h"
6. //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
7. #define jpgImageName "test.jpg"
8. extern char * chpt_lcd_mmap_addr;
9. extern unsigned int int_lcd_height;
10. extern unsigned int int_lcd_width;
11. extern unsigned int int_lcd_pixel;
12. static unsigned int width;
13. static
    unsigned int height;
14. static unsigned int channel;
15. static unsigned char jpegQuality = 100;
16. //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
17. static void jpegWrite(unsigned char* img)
18. {
19. struct jpeg_compress_struct cinfo;
20. struct jpeg_error_mgr jerr;
21. JSAMPROW row_pointer[1];
22. FILE *outfile = fopen( jpgImageName, "w");
23. // try to open file for saving
24. if (!outfile) {
25. errno_exit("jpeg");
26. }
27. // create jpeg data
28. cinfo.err = jpeg_std_error( &jerr );
29. jpeg_create_compress(&cinfo);
30. jpeg_stdio_dest(&cinfo, outfile);
31. // set image parameters
32. cinfo.image_width = width;
33. cinfo.image_height = height;
34. cinfo.input_components = 3;
35. cinfo.in_color_space = JCS_RGB;
36. // set jpeg compression parameters to default
37. jpeg_set_defaults(&cinfo);
38. // and then adjust quality setting
39. jpeg_set_quality(&cinfo, jpegQuality, TRUE);
40. // start compress
41. jpeg_start_compress(&cinfo, TRUE);
42. // feed data
43. while (cinfo.next_scanline < cinfo.image_height)
44. {
45. row_pointer[0] = &img[(cinfo.image_height - cinfo.next_scanline - 1) * cinfo.image_width*3];
46. jpeg_write_scanlines(&cinfo, row_pointer, 1);
47. }
48. // finish compression
49. jpeg_finish_compress(&cinfo);
50. // destroy jpeg data
51. jpeg_destroy_compress(&cinfo);
52. // close output file
53. fclose(outfile);
54. }
55. void jpgImageProduct(const void* p)
56. {
57. usleep(500000);
58. unsigned char* dst;
59. unsigned char* src = (unsigned char*)p;
60. unsigned int j;
61. unsigned int i;
62. width = int_lcd_width;
63. height = int_lcd_height;
64. dst = (unsigned char*)malloc (width*height*3+66);
65. for (i=0; i< height; i++)
66. {
67. for(j=0;j<width;j++)
68. {
69. memcpy(dst+(i*width+j)*3, src+(i*width+j)*4+2,1);
70. memcpy(dst+(i*width+j)*3+1, src+(i*width+j)*4+1,1);
71. memcpy(dst+(i*width+j)*3+2, src+(i*width+j)*4,1);
72. }
73. }
74. jpegWrite(dst);
75. free(dst);
76. }

/*
 *     jpg.c
 *
 */

#include "classroom.h"

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#define jpgImageName "test.jpg"

extern char * chpt_lcd_mmap_addr;
extern unsigned int int_lcd_height;
extern unsigned int int_lcd_width;
extern unsigned int int_lcd_pixel;

static unsigned int width;
static unsigned int height;
static unsigned int channel;

static unsigned char jpegQuality = 100;

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

static void jpegWrite(unsigned char* img)
{
  struct jpeg_compress_struct cinfo;
  struct jpeg_error_mgr jerr;
	
  JSAMPROW row_pointer[1];
  FILE *outfile = fopen( jpgImageName, "w");

  // try to open file for saving
  if (!outfile) {
    errno_exit("jpeg");
  }

  // create jpeg data
  cinfo.err = jpeg_std_error( &jerr );
  jpeg_create_compress(&cinfo);
  jpeg_stdio_dest(&cinfo, outfile);

  // set image parameters
  cinfo.image_width = width;	
  cinfo.image_height = height;
  cinfo.input_components = 3;
  cinfo.in_color_space = JCS_RGB;

  // set jpeg compression parameters to default
  jpeg_set_defaults(&cinfo);
  // and then adjust quality setting
  jpeg_set_quality(&cinfo, jpegQuality, TRUE);

  // start compress 
  jpeg_start_compress(&cinfo, TRUE);

  // feed data
  while (cinfo.next_scanline < cinfo.image_height) 
  {
	row_pointer[0] = &img[(cinfo.image_height - cinfo.next_scanline - 1) * cinfo.image_width*3];
    jpeg_write_scanlines(&cinfo, row_pointer, 1);
  }

  // finish compression
  jpeg_finish_compress(&cinfo);

  // destroy jpeg data
  jpeg_destroy_compress(&cinfo);

  // close output file
  fclose(outfile);
}


void jpgImageProduct(const void* p)
{
	usleep(500000);

	unsigned char* dst;
	unsigned char* src = (unsigned char*)p;
	unsigned int j;
	unsigned int i;

	width = int_lcd_width;
    height = int_lcd_height;

	dst = (unsigned char*)malloc (width*height*3+66);

	for (i=0; i< height; i++)
	{
		for(j=0;j<width;j++)
		{
			memcpy(dst+(i*width+j)*3, src+(i*width+j)*4+2,1);
			memcpy(dst+(i*width+j)*3+1, src+(i*width+j)*4+1,1);
			memcpy(dst+(i*width+j)*3+2, src+(i*width+j)*4,1);
		}
	}
	jpegWrite(dst);
	free(dst);
}