ffmpeg 的管道问题

使用管道为ffmpeg输入视频内容.

首先 建立管道 FIFO. 把 JPG 内容不断的送往 FIFO中.
然后 命令行 ffmpeg  -f bmp_pipe -i t.v -r 1 -y a.flv  即可产生视频流

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1. #include <unistd.h>
   
2. #include <stdlib.h>
   
3. #include <string.h>
   
4. #include <stdio.h>
   
5. #include <sys/types.h>
   
6. #include <sys/stat.h>
   
7. #include <fcntl.h>
   
8. 
   
9. 
   
10. //摄像头通用接口
    
11. #include <opencv2/opencv.hpp>
    
12. #include <opencv2/highgui/highgui.hpp>
    
13. #include <opencv2/imgproc/imgproc.hpp>
    
14. #include <opencv2/core/core.hpp>
    
15. #include <opencv2/objdetect/objdetect.hpp>
    
16. #include <signal.h>
    
17. #include <sys/socket.h>
    
18. #include <arpa/inet.h>
    
19. #include <netinet/in.h>
    
20. using namespace cv;
    
21. /* Video 通用接口 */
    
22. typedef struct {
    
23.     int             idx;
    
24.     VideoCapture     *stream;
    
25.     Mat                frame;
    
26. }WebcamContext;
    
27. static WebcamContext gCtx[3] = {0}; //目前最大支持 3 个摄像头.
    
28. 
    
29. //打开摄像头
    
30. static int InitCameraViaID(int idx, int camera_idx, int w, int h)
    
31. {
    
32.     //参数检查
    
33.     gCtx[idx].stream = new VideoCapture(camera_idx);
    
34.     if (!gCtx[idx].stream) {
    
35.         printf("Cannot open Camera %d\n", camera_idx);
    
36.         exit(-1);
    
37.         return -1;
    
38.     }
    
39.     gCtx[idx].stream->set(CV_CAP_PROP_FRAME_WIDTH, w);
    
40.     gCtx[idx].stream->set(CV_CAP_PROP_FRAME_HEIGHT, h);
    
41.     return 0;
    
42. }
    
43. 
    
44. static void FinalCamera(void)
    
45. {
    
46.     for (int i=0; i<sizeof(gCtx)/sizeof(gCtx[0]); i++) {
    
47.         if (gCtx[i].stream) {
    
48.             gCtx[i].stream->release();
    
49.             gCtx[i].stream = NULL;
    
50.             if (!gCtx[i].frame.empty())
    
51.                 gCtx[i].frame.release();
    
52.         }
    
53.     }
    
54. }
    
55. 
    
56. //获取摄像头的数据
    
57. static Mat Get_Picture(int idx)
    
58. {
    
59.     gCtx[idx].stream->read(gCtx[idx].frame);
    
60.     return gCtx[idx].frame;
    
61. }
    
62. 
    
63. static int fd_fifo = -1;
    
64. 
    
65. static void save_bmp_to_file(int idx, uint8_t* bmp, int bmp_size)
    
66. {    
    
67.     if (fd_fifo = -1) {
    
68.         char filename[128];
    
69.         //sprintf(filename, "/tmp/jpg/%d.bmp", idx);
    
70.         sprintf(filename, "/tmp/jpg/t.v");
    
71.         int fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
    
72.         if (fd > 0) {
    
73.             fd_fifo = fd;
    
74.         }    
    
75.     }
    
76.     
    
77.     if (fd_fifo > 0) {
    
78.         write(fd_fifo, bmp, bmp_size);
    
79.     }
    
80.     
    
81.     if ((fd_fifo > 0) && ((bmp_size==0) || (bmp == NULL))) {
    
82.         close(fd_fifo);
    
83.     }    
    
84. }
    
85. 
    
86. #define dbg()        printf("%d.\n", __LINE__)
    
87. static uint8_t* convert_Mat_to_BMP(Mat *img, int *bmp_size);
    
88. 
    
89. int main(int argc, char **argv)
    
90. {
    
91.     int idx = 0;
    
92.     
    
93.     InitCameraViaID(0, 1, 800, 600);
    
94.     
    
95.     int bmp_size, fd;
    
96.     uint8_t* bmp = NULL;
    
97.     
    
98.     //while (idx++ < 100) 
99.     while (1)
    
100.     {
     
101.         Mat frame = Get_Picture(0);                
     
102.         bmp = convert_Mat_to_BMP(&frame, &bmp_size);
     
103.         save_bmp_to_file(idx, bmp, bmp_size);
     
104.         
     
105.         usleep(100000);    
     
106.     }
     
107.     save_bmp_to_file(0, NULL, 0);
     
108.     
     
109.     FinalCamera();
     
110.     return 0;
     
111. }
     
112. 
     
113. //convert Mat-object to bmp-struct.
     
114. 
     
115. //https://www.cnblogs.com/lzlsky/archive/2012/08/16/2641698.html
     
116. typedef uint32_t            DWORD;
     
117. typedef uint16_t            WORD;
     
118. typedef int32_t                LONG;
     
119. typedef uint8_t                BYTE;
     
120. 
     
121. typedef struct tagBITMAPFILEHEADER {
     
122.     WORD    bfType;                 //2
     
123.     DWORD    bfSize;                 //6
     
124.     WORD    bfReserved1;             //8
     
125.     WORD    bfReserved2;             //10
     
126.     DWORD    bfOffBits;                 //14
     
127. } __attribute__((packed)) BITMAPFILEHEADER;
     
128. 
     
129. typedef struct tagBITMAPINFOHEADER{
     
130.     DWORD        biSize;             //4
     
131.     LONG        biWidth;             //8
     
132.     LONG        biHeight;             //12
     
133.     WORD        biPlanes;             //14
     
134.     WORD        biBitCount;         //16
     
135.     DWORD        biCompression;         //20
     
136.     DWORD        biSizeImage;         //24
     
137.     LONG        biXPelsPerMeter;     //28
     
138.     LONG        biYPelsPerMeter;     //32
     
139.     DWORD        biClrUsed;             //36
     
140.     DWORD        biClrImportant;     //40
     
141. } __attribute__((packed)) BITMAPINFOHEADER;
     
142. 
     
143. 
     
144. typedef struct tagRGBQUAD {
     
145.     BYTE rgbBlue;
     
146.     BYTE rgbGreen;
     
147.     BYTE rgbRed;
     
148.     BYTE rgbReserved;
     
149. } __attribute__((packed)) RGBQUAD;
     
150. 
     
151. //return the pointer of BMP-in-memeory.
     
152. /*
     
153. input: Mat -> img
     
154. output: bmp_size
     
155. return: bmp_buffer pointer. (need to free by USER)
     
156. */
     
157. static uint8_t *convert_Mat_to_BMP(Mat *img, int *bmp_size)
     
158. {
     
159.     uint8_t *pBmpArray = NULL;
     
160.     //======建立位图信息 ===========
     
161.     int width, height, depth, channel;
     
162.     width = img->cols;
     
163.     height = img->rows;
     
164.     depth = img->depth();
     
165.     channel = img->channels();
     
166.     
     
167.     printf("w=%d h=%d d=%d c=%d\n", width, height, depth, channel);
     
168.     
     
169.     int bits, colors;
     
170.     uint8_t idx;
     
171.     bits = (8 << (depth/2)) * channel;
     
172.     
     
173. #if 0    
     
174.     if (bits > 8)
     
175.         colors = 0;
     
176.     else
     
177.         colors = 1<<bits; //now, bits must be 8; so color = 256
     
178. #endif
     
179.         
     
180.     if (bits == 24)
     
181.         bits = 32;
     
182.         
     
183.     //待存储图像数据每行字节数为4的倍数
     
184.     int lineByte=(width * bits/8+3)/4*4;
     
185.     
     
186.     int colorTablesize = 0;
     
187.     if (bits == 8) { // 256 色位图, // 设置灰阶调色板
     
188.         colorTablesize = 256 * sizeof(RGBQUAD);
     
189.     }    
     
190. ///////////////////////////////////////////////////////////////////////////////////////////////////////////    
     
191.     DWORD    bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + colorTablesize + lineByte*height;
     
192.     //bitmap 文件 buffer
     
193.     pBmpArray = (uint8_t *)malloc(bfSize);
     
194.     memset(pBmpArray, 0, bfSize);
     
195.     *bmp_size = bfSize;
     
196. ///////////////////////////////////////////////////////////////////////////////////////////////////////////    
     
197.     BITMAPFILEHEADER *fileHead = (BITMAPFILEHEADER *)pBmpArray; // sizeof(BITMAPFILEHEADER) = 14;
     
198.     fileHead->bfType = 0x4D42;    //bmp类型
     
199.     //bfSize是图像文件4个组成部分之和
     
200.     fileHead->bfSize = bfSize;
     
201.     //bfOffBits是图像文件前3个部分所需空间之和
     
202.     fileHead->bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + colorTablesize;
     
203. ///////////////////////////////////////////////////////////////////////////////////////////////////////////    
     
204.     //位图的头
     
205.     BITMAPINFOHEADER *head = (BITMAPINFOHEADER *)(&pBmpArray[sizeof(BITMAPFILEHEADER)]); // sizeof(BITMAPINFOHEADER) = 40;
     
206.     head->biSize            = 40;
     
207.     head->biWidth            = width;
     
208.     head->biHeight            = height;
     
209.     head->biPlanes            = 1;
     
210.     head->biBitCount        = bits; //表示颜色用到的位数
     
211.     head->biCompression        = 0; //0:不压缩(用BI_RGB表示)
     
212.     head->biSizeImage        = lineByte*height; //图像数据站的字节数
     
213.     head->biXPelsPerMeter    = 0;
     
214.     head->biYPelsPerMeter    = 0;
     
215.     head->biClrUsed            = 0;
     
216.     head->biClrImportant    = 0;
     
217. ///////////////////////////////////////////////////////////////////////////////////////////////////////////    
     
218.     RGBQUAD *VgaColorTab = (RGBQUAD *)(&pBmpArray[sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER)]);
     
219.     if (bits == 8) { // 256 色位图, // 设置灰阶调色板
     
220.         for (idx=0;idx<256;idx++) {
     
221.             VgaColorTab[idx].rgbRed=VgaColorTab[idx].rgbGreen=VgaColorTab[idx].rgbBlue= idx;
     
222.         }
     
223.     }
     
224. ///////////////////////////////////////////////////////////////////////////////////////////////////////////
     
225.     //======颠倒数据
     
226.     //======Mat 中从上往下存,而 bitmap 中从下往上存。 都是从左往右,并 且 bitmap 每一个点多占一个保留字节,默认 255
     
227.     unsigned char *m_pDibBits = pBmpArray + fileHead->bfOffBits ;//存储图像中的数据,从下向上,从左向右 //x行 * Y列
     
228.     int x, y;
     
229.     unsigned char * bmpdata;
     
230.     unsigned char * imgData = img->data;
     
231.     
     
232.     if (bits == 8)
     
233.     {
     
234.         //把 imgData 中的第一行复制到 m_pDibBits 的最后一行 , 依次颠倒
     
235.         for (x=0; x<height; x++ )
     
236.         {
     
237.             bmpdata = m_pDibBits + (height-1-x)*width;
     
238.             memcpy(bmpdata,imgData,width);
     
239.             imgData = imgData + width;
     
240.         }
     
241.     }
     
242.     else if (bits == 32)
     
243.     {
     
244.         //把 imgData 中的第一行复制到 m_pDibBits 的最后一行 , 依次颠倒
     
245.         for (x=0; x<height; x++ )
     
246.         {
     
247.             bmpdata = m_pDibBits + (height-1-x)*width*4;
     
248.             for (y = 0; y<width; y++)
     
249.             {
     
250.                 memcpy(bmpdata,imgData,3);
     
251.                 bmpdata[3] = 255;
     
252.                 bmpdata = bmpdata+4;
     
253.                 imgData = imgData+3;
     
254.             }
     
255.         }
     
256.     }
     
257.     
     
258. ///////////////////////////////////////////////////////////////////////////////////////////////////////////
     
259.     return pBmpArray;
     
260. }

衍生一下, 使用opencv 处理图像, 图像通过FIFO给 ffmpeg用,即可.