发布:04_V4L2应用程序开发_获取数据,05_V4L2应用程序开发_调试,06_V4L2应用程序开发_控制亮度

IMX6ULL/doc_pic/13_V4L2/01_V4L2应用程序开发.md

@@ -441,11 +441,31 @@ int main(int argc, char **argv)
 
 ### 3.2 获取数据
 
+根据《1.2 完整的使用流程》来编写程序，步骤如下：
+
+* 打开设备
+* ioctl VIDIOC_QUERYCAP：Query Capbility，查询能力
+* 枚举格式、设置格式
+* ioctl VIDIOC_REQBUFS：申请buffer
+* ioctl VIDIOC_QUERYBUF和mmap：查询buffer信息、映射
+* ioctl VIDIOC_QBUF：把buffer放入"空闲链表"
+* ioctl VIDIOC_STREAMON：启动摄像头
+* 这里是一个循环：使用poll/select监测buffer，然后从"完成链表"中取出buffer，处理后再放入"空闲链表"
+  * poll/select
+  * ioctl VIDIOC_DQBUF：从"完成链表"中取出buffer
+  * 处理：前面使用mmap映射了每个buffer的地址，把这个buffer的数据存为文件
+  * ioclt VIDIOC_QBUF：把buffer放入"空闲链表"
+* ioctl VIDIOC_STREAMOFF：停止摄像头
+
+![image-20230726162003001](pic/19_get_data.png)
+
+
+
 
 
 ### 3.3 控制亮度
 
-
+![image-20230726170548040](pic/20_brightness.png)
 
 
 

IMX6ULL/doc_pic/13_V4L2/笔记.md

@@ -46,7 +46,7 @@ sensor---串行器---GSML---->解串器---->soc（mipi接口）这一条路也
 
 ## 3. 学习笔记
 
-
+好文：https://zhuanlan.zhihu.com/p/613018868
 
 Linux V4L2子系统分析（一）: https://blog.csdn.net/u011037593/article/details/115415136
 

IMX6ULL/source/13_V4L2/04_video_get_data/video_test.c

@@ -0,0 +1,237 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/types.h>          /* for videodev2.h */
+#include <linux/videodev2.h>
+#include <poll.h>
+#include <sys/mman.h>
+
+/* ./video_test </dev/video0> */
+
+int main(int argc, char **argv)
+{
+    int fd;
+    struct v4l2_fmtdesc fmtdesc;
+    struct v4l2_frmsizeenum fsenum;
+    int fmt_index = 0;
+    int frame_index = 0;
+    int i;
+    void *bufs[32];
+    int buf_cnt;
+    int type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    struct pollfd fds[1];
+    char filename[32];
+    int file_cnt = 0;
+
+    if (argc != 2)
+    {
+        printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
+        return -1;
+    }
+
+    /* open */
+    fd = open(argv[1], O_RDWR);
+    if (fd < 0)
+    {
+        printf("can not open %s\n", argv[1]);
+        return -1;
+    }
+
+    /* 查询能力 */
+    struct v4l2_capability cap;
+    memset(&cap, 0, sizeof(struct v4l2_capability));
+    
+    if (0 == ioctl(fd, VIDIOC_QUERYCAP, &cap))
+    {        
+        if((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
+            fprintf(stderr, "Error opening device %s: video capture not supported.\n",
+                    argv[1]);
+            return -1;
+        }
+        
+        if(!(cap.capabilities & V4L2_CAP_STREAMING)) {
+            fprintf(stderr, "%s does not support streaming i/o\n", argv[1]);
+            return -1;
+        }
+    }
+    else
+    {
+        printf("can not get capability\n");
+        return -1;
+    }
+
+    while (1)
+    {
+        /* 枚举格式 */
+        fmtdesc.index = fmt_index;  // 比如从0开始
+        fmtdesc.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;  // 指定type为"捕获"
+        if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
+            break;
+
+        frame_index = 0;
+        while (1)
+        {
+            /* 枚举这种格式所支持的帧大小 */
+            memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
+            fsenum.pixel_format = fmtdesc.pixelformat;
+            fsenum.index = frame_index;
+
+            if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
+            {
+                printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
+            }
+            else
+            {
+                break;
+            }
+
+            frame_index++;
+        }
+
+        fmt_index++;
+    }
+
+
+    /* 设置格式 */
+    struct v4l2_format fmt;
+    memset(&fmt, 0, sizeof(struct v4l2_format));
+    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    fmt.fmt.pix.width = 1024;
+    fmt.fmt.pix.height = 768;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
+    fmt.fmt.pix.field = V4L2_FIELD_ANY;
+    if (0 == ioctl(fd, VIDIOC_S_FMT, &fmt))
+    {
+        printf("set format ok: %d x %d\n", fmt.fmt.pix.width, fmt.fmt.pix.height);
+    }
+    else
+    {
+        printf("can not set format\n");
+        return -1;
+    }
+
+    /*
+     * 申请buffer
+     */
+    struct v4l2_requestbuffers rb;
+    memset(&rb, 0, sizeof(struct v4l2_requestbuffers));
+    rb.count = 32;
+    rb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    rb.memory = V4L2_MEMORY_MMAP;
+
+    if (0 == ioctl(fd, VIDIOC_REQBUFS, &rb))
+    {
+        /* 申请成功后, mmap这些buffer */
+        buf_cnt = rb.count;
+        for(i = 0; i < rb.count; i++) {
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.index = i;
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            if (0 == ioctl(fd, VIDIOC_QUERYBUF, &buf))
+            {
+                /* mmap */
+                bufs[i] = mmap(0 /* start anywhere */ ,
+                                  buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+                                  buf.m.offset);
+                if(bufs[i] == MAP_FAILED) {
+                    perror("Unable to map buffer");
+                    return -1;
+                }
+            }
+            else
+            {
+                printf("can not query buffer\n");
+                return -1;
+            }            
+        }
+
+        printf("map %d buffers ok\n", buf_cnt);
+        
+    }
+    else
+    {
+        printf("can not request buffers\n");
+        return -1;
+    }
+
+    /* 把所有buffer放入"空闲链表" */
+    for(i = 0; i < buf_cnt; ++i) {
+        struct v4l2_buffer buf;
+        memset(&buf, 0, sizeof(struct v4l2_buffer));
+        buf.index = i;
+        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+        buf.memory = V4L2_MEMORY_MMAP;
+        if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+        {
+            perror("Unable to queue buffer");
+            return -1;
+        }
+    }
+    printf("queue buffers ok\n");
+
+    /* 启动摄像头 */
+    if (0 != ioctl(fd, VIDIOC_STREAMON, &type))
+    {
+        perror("Unable to start capture");
+        return -1;
+    }
+    printf("start capture ok\n");
+
+    while (1)
+    {
+        /* poll */
+        memset(fds, 0, sizeof(fds));
+        fds[0].fd = fd;
+        fds[0].events = POLLIN;
+        if (1 == poll(fds, 1, -1))
+        {
+            /* 把buffer取出队列 */
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            
+            if (0 != ioctl(fd, VIDIOC_DQBUF, &buf))
+            {
+                perror("Unable to dequeue buffer");
+                return -1;
+            }
+            
+            /* 把buffer的数据存为文件 */
+            sprintf(filename, "video_raw_data_%04d.jpg", file_cnt++);
+            int fd_file = open(filename, O_RDWR | O_CREAT, 0666);
+            if (fd_file < 0)
+            {
+                printf("can not create file : %s\n", filename);
+            }
+            printf("capture to %s\n", filename);
+            write(fd_file, bufs[buf.index], buf.bytesused);
+            close(fd_file);
+
+            /* 把buffer放入队列 */
+            if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+            {
+                perror("Unable to queue buffer");
+                return -1;
+            }
+        }
+    }
+
+    if (0 != ioctl(fd, VIDIOC_STREAMOFF, &type))
+    {
+        perror("Unable to stop capture");
+        return -1;
+    }
+    printf("stop capture ok\n");
+    close(fd);
+
+    return 0;
+}
+

IMX6ULL/source/13_V4L2/05_video_brightness/video_test.c

@@ -0,0 +1,289 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/types.h>          /* for videodev2.h */
+#include <linux/videodev2.h>
+#include <poll.h>
+#include <sys/mman.h>
+#include <pthread.h>
+
+/* ./video_test </dev/video0> */
+
+static void *thread_brightness_control (void *args)
+{
+    int fd = (int)args;
+
+    unsigned char c;
+    int brightness;
+    int delta;
+    
+    struct v4l2_queryctrl   qctrl;
+    memset(&qctrl, 0, sizeof(qctrl));
+    qctrl.id = V4L2_CID_BRIGHTNESS; // V4L2_CID_BASE+0;
+    if (0 != ioctl(fd, VIDIOC_QUERYCTRL, &qctrl))
+    {
+        printf("can not query brightness\n");
+        return NULL;
+    }
+
+    printf("brightness min = %d, max = %d\n", qctrl.minimum, qctrl.maximum);
+    delta = (qctrl.maximum - qctrl.minimum) / 10;
+        
+    struct v4l2_control ctl;
+    ctl.id = V4L2_CID_BRIGHTNESS; // V4L2_CID_BASE+0;
+    ioctl(fd, VIDIOC_G_CTRL, &ctl);
+
+    while (1)
+    {
+        c = getchar();
+        if (c == 'u' || c == 'U')
+        {
+            ctl.value += delta;
+        }
+        else if (c == 'd' || c == 'D')
+        {
+            ctl.value -= delta;
+        }
+        if (ctl.value > qctrl.maximum)
+            ctl.value = qctrl.maximum;
+        if (ctl.value < qctrl.minimum)
+            ctl.value = qctrl.minimum;
+
+        ioctl(fd, VIDIOC_S_CTRL, &ctl);
+    }
+    return NULL;
+}
+
+int main(int argc, char **argv)
+{
+    int fd;
+    struct v4l2_fmtdesc fmtdesc;
+    struct v4l2_frmsizeenum fsenum;
+    int fmt_index = 0;
+    int frame_index = 0;
+    int i;
+    void *bufs[32];
+    int buf_cnt;
+    int type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    struct pollfd fds[1];
+    char filename[32];
+    int file_cnt = 0;
+
+    if (argc != 2)
+    {
+        printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
+        return -1;
+    }
+
+    /* open */
+    fd = open(argv[1], O_RDWR);
+    if (fd < 0)
+    {
+        printf("can not open %s\n", argv[1]);
+        return -1;
+    }
+
+    /* 查询能力 */
+    struct v4l2_capability cap;
+    memset(&cap, 0, sizeof(struct v4l2_capability));
+    
+    if (0 == ioctl(fd, VIDIOC_QUERYCAP, &cap))
+    {        
+        if((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
+            fprintf(stderr, "Error opening device %s: video capture not supported.\n",
+                    argv[1]);
+            return -1;
+        }
+        
+        if(!(cap.capabilities & V4L2_CAP_STREAMING)) {
+            fprintf(stderr, "%s does not support streaming i/o\n", argv[1]);
+            return -1;
+        }
+    }
+    else
+    {
+        printf("can not get capability\n");
+        return -1;
+    }
+
+    while (1)
+    {
+        /* 枚举格式 */
+        fmtdesc.index = fmt_index;  // 比如从0开始
+        fmtdesc.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;  // 指定type为"捕获"
+        if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
+            break;
+
+        frame_index = 0;
+        while (1)
+        {
+            /* 枚举这种格式所支持的帧大小 */
+            memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
+            fsenum.pixel_format = fmtdesc.pixelformat;
+            fsenum.index = frame_index;
+
+            if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
+            {
+                printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
+            }
+            else
+            {
+                break;
+            }
+
+            frame_index++;
+        }
+
+        fmt_index++;
+    }
+
+
+    /* 设置格式 */
+    struct v4l2_format fmt;
+    memset(&fmt, 0, sizeof(struct v4l2_format));
+    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    fmt.fmt.pix.width = 1024;
+    fmt.fmt.pix.height = 768;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
+    fmt.fmt.pix.field = V4L2_FIELD_ANY;
+    if (0 == ioctl(fd, VIDIOC_S_FMT, &fmt))
+    {
+        printf("set format ok: %d x %d\n", fmt.fmt.pix.width, fmt.fmt.pix.height);
+    }
+    else
+    {
+        printf("can not set format\n");
+        return -1;
+    }
+
+    /*
+     * 申请buffer
+     */
+    struct v4l2_requestbuffers rb;
+    memset(&rb, 0, sizeof(struct v4l2_requestbuffers));
+    rb.count = 32;
+    rb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    rb.memory = V4L2_MEMORY_MMAP;
+
+    if (0 == ioctl(fd, VIDIOC_REQBUFS, &rb))
+    {
+        /* 申请成功后, mmap这些buffer */
+        buf_cnt = rb.count;
+        for(i = 0; i < rb.count; i++) {
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.index = i;
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            if (0 == ioctl(fd, VIDIOC_QUERYBUF, &buf))
+            {
+                /* mmap */
+                bufs[i] = mmap(0 /* start anywhere */ ,
+                                  buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+                                  buf.m.offset);
+                if(bufs[i] == MAP_FAILED) {
+                    perror("Unable to map buffer");
+                    return -1;
+                }
+            }
+            else
+            {
+                printf("can not query buffer\n");
+                return -1;
+            }            
+        }
+
+        printf("map %d buffers ok\n", buf_cnt);
+        
+    }
+    else
+    {
+        printf("can not request buffers\n");
+        return -1;
+    }
+
+    /* 把所有buffer放入"空闲链表" */
+    for(i = 0; i < buf_cnt; ++i) {
+        struct v4l2_buffer buf;
+        memset(&buf, 0, sizeof(struct v4l2_buffer));
+        buf.index = i;
+        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+        buf.memory = V4L2_MEMORY_MMAP;
+        if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+        {
+            perror("Unable to queue buffer");
+            return -1;
+        }
+    }
+    printf("queue buffers ok\n");
+
+    /* 启动摄像头 */
+    if (0 != ioctl(fd, VIDIOC_STREAMON, &type))
+    {
+        perror("Unable to start capture");
+        return -1;
+    }
+    printf("start capture ok\n");
+
+
+    /* 创建线程用来控制亮度 */
+    pthread_t thread;
+    pthread_create(&thread, NULL, thread_brightness_control, (void *)fd);
+   
+
+    while (1)
+    {
+        /* poll */
+        memset(fds, 0, sizeof(fds));
+        fds[0].fd = fd;
+        fds[0].events = POLLIN;
+        if (1 == poll(fds, 1, -1))
+        {
+            /* 把buffer取出队列 */
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            
+            if (0 != ioctl(fd, VIDIOC_DQBUF, &buf))
+            {
+                perror("Unable to dequeue buffer");
+                return -1;
+            }
+            
+            /* 把buffer的数据存为文件 */
+            sprintf(filename, "video_raw_data_%04d.jpg", file_cnt++);
+            int fd_file = open(filename, O_RDWR | O_CREAT, 0666);
+            if (fd_file < 0)
+            {
+                printf("can not create file : %s\n", filename);
+            }
+            printf("capture to %s\n", filename);
+            write(fd_file, bufs[buf.index], buf.bytesused);
+            close(fd_file);
+
+            /* 把buffer放入队列 */
+            if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+            {
+                perror("Unable to queue buffer");
+                return -1;
+            }
+        }
+    }
+
+    if (0 != ioctl(fd, VIDIOC_STREAMOFF, &type))
+    {
+        perror("Unable to stop capture");
+        return -1;
+    }
+    printf("stop capture ok\n");
+    close(fd);
+
+    return 0;
+}
+

README.md

@@ -784,8 +784,11 @@ git clone https://e.coding.net/weidongshan/linux/doc_and_source_for_drivers.git
 
   ```shell
   03_V4L2应用程序开发_列出帧细节
+  04_V4L2应用程序开发_获取数据
+05_V4L2应用程序开发_调试
+  06_V4L2应用程序开发_控制亮度
   ```
-
+  
   
 
 

STM32MP157/doc_pic/13_V4L2/01_V4L2应用程序开发.md

@@ -441,11 +441,31 @@ int main(int argc, char **argv)
 
 ### 3.2 获取数据
 
+根据《1.2 完整的使用流程》来编写程序，步骤如下：
+
+* 打开设备
+* ioctl VIDIOC_QUERYCAP：Query Capbility，查询能力
+* 枚举格式、设置格式
+* ioctl VIDIOC_REQBUFS：申请buffer
+* ioctl VIDIOC_QUERYBUF和mmap：查询buffer信息、映射
+* ioctl VIDIOC_QBUF：把buffer放入"空闲链表"
+* ioctl VIDIOC_STREAMON：启动摄像头
+* 这里是一个循环：使用poll/select监测buffer，然后从"完成链表"中取出buffer，处理后再放入"空闲链表"
+  * poll/select
+  * ioctl VIDIOC_DQBUF：从"完成链表"中取出buffer
+  * 处理：前面使用mmap映射了每个buffer的地址，把这个buffer的数据存为文件
+  * ioclt VIDIOC_QBUF：把buffer放入"空闲链表"
+* ioctl VIDIOC_STREAMOFF：停止摄像头
+
+![image-20230726162003001](pic/19_get_data.png)
+
+
+
 
 
 ### 3.3 控制亮度
 
-
+![image-20230726170548040](pic/20_brightness.png)
 
 
 

STM32MP157/doc_pic/13_V4L2/笔记.md

@@ -46,7 +46,7 @@ sensor---串行器---GSML---->解串器---->soc（mipi接口）这一条路也
 
 ## 3. 学习笔记
 
-
+好文：https://zhuanlan.zhihu.com/p/613018868
 
 Linux V4L2子系统分析（一）: https://blog.csdn.net/u011037593/article/details/115415136
 

STM32MP157/source/A7/13_V4L2/04_video_get_data/video_test.c

@@ -0,0 +1,237 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/types.h>          /* for videodev2.h */
+#include <linux/videodev2.h>
+#include <poll.h>
+#include <sys/mman.h>
+
+/* ./video_test </dev/video0> */
+
+int main(int argc, char **argv)
+{
+    int fd;
+    struct v4l2_fmtdesc fmtdesc;
+    struct v4l2_frmsizeenum fsenum;
+    int fmt_index = 0;
+    int frame_index = 0;
+    int i;
+    void *bufs[32];
+    int buf_cnt;
+    int type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    struct pollfd fds[1];
+    char filename[32];
+    int file_cnt = 0;
+
+    if (argc != 2)
+    {
+        printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
+        return -1;
+    }
+
+    /* open */
+    fd = open(argv[1], O_RDWR);
+    if (fd < 0)
+    {
+        printf("can not open %s\n", argv[1]);
+        return -1;
+    }
+
+    /* 查询能力 */
+    struct v4l2_capability cap;
+    memset(&cap, 0, sizeof(struct v4l2_capability));
+    
+    if (0 == ioctl(fd, VIDIOC_QUERYCAP, &cap))
+    {        
+        if((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
+            fprintf(stderr, "Error opening device %s: video capture not supported.\n",
+                    argv[1]);
+            return -1;
+        }
+        
+        if(!(cap.capabilities & V4L2_CAP_STREAMING)) {
+            fprintf(stderr, "%s does not support streaming i/o\n", argv[1]);
+            return -1;
+        }
+    }
+    else
+    {
+        printf("can not get capability\n");
+        return -1;
+    }
+
+    while (1)
+    {
+        /* 枚举格式 */
+        fmtdesc.index = fmt_index;  // 比如从0开始
+        fmtdesc.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;  // 指定type为"捕获"
+        if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
+            break;
+
+        frame_index = 0;
+        while (1)
+        {
+            /* 枚举这种格式所支持的帧大小 */
+            memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
+            fsenum.pixel_format = fmtdesc.pixelformat;
+            fsenum.index = frame_index;
+
+            if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
+            {
+                printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
+            }
+            else
+            {
+                break;
+            }
+
+            frame_index++;
+        }
+
+        fmt_index++;
+    }
+
+
+    /* 设置格式 */
+    struct v4l2_format fmt;
+    memset(&fmt, 0, sizeof(struct v4l2_format));
+    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    fmt.fmt.pix.width = 1024;
+    fmt.fmt.pix.height = 768;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
+    fmt.fmt.pix.field = V4L2_FIELD_ANY;
+    if (0 == ioctl(fd, VIDIOC_S_FMT, &fmt))
+    {
+        printf("set format ok: %d x %d\n", fmt.fmt.pix.width, fmt.fmt.pix.height);
+    }
+    else
+    {
+        printf("can not set format\n");
+        return -1;
+    }
+
+    /*
+     * 申请buffer
+     */
+    struct v4l2_requestbuffers rb;
+    memset(&rb, 0, sizeof(struct v4l2_requestbuffers));
+    rb.count = 32;
+    rb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    rb.memory = V4L2_MEMORY_MMAP;
+
+    if (0 == ioctl(fd, VIDIOC_REQBUFS, &rb))
+    {
+        /* 申请成功后, mmap这些buffer */
+        buf_cnt = rb.count;
+        for(i = 0; i < rb.count; i++) {
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.index = i;
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            if (0 == ioctl(fd, VIDIOC_QUERYBUF, &buf))
+            {
+                /* mmap */
+                bufs[i] = mmap(0 /* start anywhere */ ,
+                                  buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+                                  buf.m.offset);
+                if(bufs[i] == MAP_FAILED) {
+                    perror("Unable to map buffer");
+                    return -1;
+                }
+            }
+            else
+            {
+                printf("can not query buffer\n");
+                return -1;
+            }            
+        }
+
+        printf("map %d buffers ok\n", buf_cnt);
+        
+    }
+    else
+    {
+        printf("can not request buffers\n");
+        return -1;
+    }
+
+    /* 把所有buffer放入"空闲链表" */
+    for(i = 0; i < buf_cnt; ++i) {
+        struct v4l2_buffer buf;
+        memset(&buf, 0, sizeof(struct v4l2_buffer));
+        buf.index = i;
+        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+        buf.memory = V4L2_MEMORY_MMAP;
+        if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+        {
+            perror("Unable to queue buffer");
+            return -1;
+        }
+    }
+    printf("queue buffers ok\n");
+
+    /* 启动摄像头 */
+    if (0 != ioctl(fd, VIDIOC_STREAMON, &type))
+    {
+        perror("Unable to start capture");
+        return -1;
+    }
+    printf("start capture ok\n");
+
+    while (1)
+    {
+        /* poll */
+        memset(fds, 0, sizeof(fds));
+        fds[0].fd = fd;
+        fds[0].events = POLLIN;
+        if (1 == poll(fds, 1, -1))
+        {
+            /* 把buffer取出队列 */
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            
+            if (0 != ioctl(fd, VIDIOC_DQBUF, &buf))
+            {
+                perror("Unable to dequeue buffer");
+                return -1;
+            }
+            
+            /* 把buffer的数据存为文件 */
+            sprintf(filename, "video_raw_data_%04d.jpg", file_cnt++);
+            int fd_file = open(filename, O_RDWR | O_CREAT, 0666);
+            if (fd_file < 0)
+            {
+                printf("can not create file : %s\n", filename);
+            }
+            printf("capture to %s\n", filename);
+            write(fd_file, bufs[buf.index], buf.bytesused);
+            close(fd_file);
+
+            /* 把buffer放入队列 */
+            if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+            {
+                perror("Unable to queue buffer");
+                return -1;
+            }
+        }
+    }
+
+    if (0 != ioctl(fd, VIDIOC_STREAMOFF, &type))
+    {
+        perror("Unable to stop capture");
+        return -1;
+    }
+    printf("stop capture ok\n");
+    close(fd);
+
+    return 0;
+}
+

STM32MP157/source/A7/13_V4L2/05_video_brightness/video_test.c

@@ -0,0 +1,289 @@
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/types.h>          /* for videodev2.h */
+#include <linux/videodev2.h>
+#include <poll.h>
+#include <sys/mman.h>
+#include <pthread.h>
+
+/* ./video_test </dev/video0> */
+
+static void *thread_brightness_control (void *args)
+{
+    int fd = (int)args;
+
+    unsigned char c;
+    int brightness;
+    int delta;
+    
+    struct v4l2_queryctrl   qctrl;
+    memset(&qctrl, 0, sizeof(qctrl));
+    qctrl.id = V4L2_CID_BRIGHTNESS; // V4L2_CID_BASE+0;
+    if (0 != ioctl(fd, VIDIOC_QUERYCTRL, &qctrl))
+    {
+        printf("can not query brightness\n");
+        return NULL;
+    }
+
+    printf("brightness min = %d, max = %d\n", qctrl.minimum, qctrl.maximum);
+    delta = (qctrl.maximum - qctrl.minimum) / 10;
+        
+    struct v4l2_control ctl;
+    ctl.id = V4L2_CID_BRIGHTNESS; // V4L2_CID_BASE+0;
+    ioctl(fd, VIDIOC_G_CTRL, &ctl);
+
+    while (1)
+    {
+        c = getchar();
+        if (c == 'u' || c == 'U')
+        {
+            ctl.value += delta;
+        }
+        else if (c == 'd' || c == 'D')
+        {
+            ctl.value -= delta;
+        }
+        if (ctl.value > qctrl.maximum)
+            ctl.value = qctrl.maximum;
+        if (ctl.value < qctrl.minimum)
+            ctl.value = qctrl.minimum;
+
+        ioctl(fd, VIDIOC_S_CTRL, &ctl);
+    }
+    return NULL;
+}
+
+int main(int argc, char **argv)
+{
+    int fd;
+    struct v4l2_fmtdesc fmtdesc;
+    struct v4l2_frmsizeenum fsenum;
+    int fmt_index = 0;
+    int frame_index = 0;
+    int i;
+    void *bufs[32];
+    int buf_cnt;
+    int type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    struct pollfd fds[1];
+    char filename[32];
+    int file_cnt = 0;
+
+    if (argc != 2)
+    {
+        printf("Usage: %s </dev/videoX>, print format detail for video device\n", argv[0]);
+        return -1;
+    }
+
+    /* open */
+    fd = open(argv[1], O_RDWR);
+    if (fd < 0)
+    {
+        printf("can not open %s\n", argv[1]);
+        return -1;
+    }
+
+    /* 查询能力 */
+    struct v4l2_capability cap;
+    memset(&cap, 0, sizeof(struct v4l2_capability));
+    
+    if (0 == ioctl(fd, VIDIOC_QUERYCAP, &cap))
+    {        
+        if((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
+            fprintf(stderr, "Error opening device %s: video capture not supported.\n",
+                    argv[1]);
+            return -1;
+        }
+        
+        if(!(cap.capabilities & V4L2_CAP_STREAMING)) {
+            fprintf(stderr, "%s does not support streaming i/o\n", argv[1]);
+            return -1;
+        }
+    }
+    else
+    {
+        printf("can not get capability\n");
+        return -1;
+    }
+
+    while (1)
+    {
+        /* 枚举格式 */
+        fmtdesc.index = fmt_index;  // 比如从0开始
+        fmtdesc.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;  // 指定type为"捕获"
+        if (0 != ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc))
+            break;
+
+        frame_index = 0;
+        while (1)
+        {
+            /* 枚举这种格式所支持的帧大小 */
+            memset(&fsenum, 0, sizeof(struct v4l2_frmsizeenum));
+            fsenum.pixel_format = fmtdesc.pixelformat;
+            fsenum.index = frame_index;
+
+            if (ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsenum) == 0)
+            {
+                printf("format %s,%d, framesize %d: %d x %d\n", fmtdesc.description, fmtdesc.pixelformat, frame_index, fsenum.discrete.width, fsenum.discrete.height);
+            }
+            else
+            {
+                break;
+            }
+
+            frame_index++;
+        }
+
+        fmt_index++;
+    }
+
+
+    /* 设置格式 */
+    struct v4l2_format fmt;
+    memset(&fmt, 0, sizeof(struct v4l2_format));
+    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    fmt.fmt.pix.width = 1024;
+    fmt.fmt.pix.height = 768;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
+    fmt.fmt.pix.field = V4L2_FIELD_ANY;
+    if (0 == ioctl(fd, VIDIOC_S_FMT, &fmt))
+    {
+        printf("set format ok: %d x %d\n", fmt.fmt.pix.width, fmt.fmt.pix.height);
+    }
+    else
+    {
+        printf("can not set format\n");
+        return -1;
+    }
+
+    /*
+     * 申请buffer
+     */
+    struct v4l2_requestbuffers rb;
+    memset(&rb, 0, sizeof(struct v4l2_requestbuffers));
+    rb.count = 32;
+    rb.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    rb.memory = V4L2_MEMORY_MMAP;
+
+    if (0 == ioctl(fd, VIDIOC_REQBUFS, &rb))
+    {
+        /* 申请成功后, mmap这些buffer */
+        buf_cnt = rb.count;
+        for(i = 0; i < rb.count; i++) {
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.index = i;
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            if (0 == ioctl(fd, VIDIOC_QUERYBUF, &buf))
+            {
+                /* mmap */
+                bufs[i] = mmap(0 /* start anywhere */ ,
+                                  buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+                                  buf.m.offset);
+                if(bufs[i] == MAP_FAILED) {
+                    perror("Unable to map buffer");
+                    return -1;
+                }
+            }
+            else
+            {
+                printf("can not query buffer\n");
+                return -1;
+            }            
+        }
+
+        printf("map %d buffers ok\n", buf_cnt);
+        
+    }
+    else
+    {
+        printf("can not request buffers\n");
+        return -1;
+    }
+
+    /* 把所有buffer放入"空闲链表" */
+    for(i = 0; i < buf_cnt; ++i) {
+        struct v4l2_buffer buf;
+        memset(&buf, 0, sizeof(struct v4l2_buffer));
+        buf.index = i;
+        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+        buf.memory = V4L2_MEMORY_MMAP;
+        if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+        {
+            perror("Unable to queue buffer");
+            return -1;
+        }
+    }
+    printf("queue buffers ok\n");
+
+    /* 启动摄像头 */
+    if (0 != ioctl(fd, VIDIOC_STREAMON, &type))
+    {
+        perror("Unable to start capture");
+        return -1;
+    }
+    printf("start capture ok\n");
+
+
+    /* 创建线程用来控制亮度 */
+    pthread_t thread;
+    pthread_create(&thread, NULL, thread_brightness_control, (void *)fd);
+   
+
+    while (1)
+    {
+        /* poll */
+        memset(fds, 0, sizeof(fds));
+        fds[0].fd = fd;
+        fds[0].events = POLLIN;
+        if (1 == poll(fds, 1, -1))
+        {
+            /* 把buffer取出队列 */
+            struct v4l2_buffer buf;
+            memset(&buf, 0, sizeof(struct v4l2_buffer));
+            buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+            buf.memory = V4L2_MEMORY_MMAP;
+            
+            if (0 != ioctl(fd, VIDIOC_DQBUF, &buf))
+            {
+                perror("Unable to dequeue buffer");
+                return -1;
+            }
+            
+            /* 把buffer的数据存为文件 */
+            sprintf(filename, "video_raw_data_%04d.jpg", file_cnt++);
+            int fd_file = open(filename, O_RDWR | O_CREAT, 0666);
+            if (fd_file < 0)
+            {
+                printf("can not create file : %s\n", filename);
+            }
+            printf("capture to %s\n", filename);
+            write(fd_file, bufs[buf.index], buf.bytesused);
+            close(fd_file);
+
+            /* 把buffer放入队列 */
+            if (0 != ioctl(fd, VIDIOC_QBUF, &buf))
+            {
+                perror("Unable to queue buffer");
+                return -1;
+            }
+        }
+    }
+
+    if (0 != ioctl(fd, VIDIOC_STREAMOFF, &type))
+    {
+        perror("Unable to stop capture");
+        return -1;
+    }
+    printf("stop capture ok\n");
+    close(fd);
+
+    return 0;
+}
+