Skip to content

0072_RPI4_USB_Camera.md

Latest commit

 

History

History
75 lines (61 loc) · 2.49 KB

0072_RPI4_USB_Camera.md

File metadata and controls

75 lines (61 loc) · 2.49 KB

RPI4 USB Camera

测试USB Camera

还以为摄像头坏了，结果是这个版本的内核不支持YUYV获取图像，要用MJPEG的方式获取，这样的获取的图像数据就不需要进行转换了，直接保存数据就可以看图像；

参考文档

v4l2-compliance

  • khadas 
    khadas@Khadas:sample$ v4l2-compliance | grep FAIL
                test VIDIOC_QUERY_EXT_CTRL/QUERYMENU: FAIL
                test VIDIOC_G/S_PARM: FAIL
                test VIDIOC_G_FMT: FAIL
  • rpi4 
    root@raspberrypi:/home/pi# v4l2-compliance | grep FAIL
        test VIDIOC_QUERY_EXT_CTRL/QUERYMENU: FAIL
        test VIDIOC_G/S_CTRL: FAIL
        test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL
        test VIDIOC_G/S_PARM: FAIL
        test VIDIOC_REQBUFS/CREATE_BUFS/QUERYBUF: FAIL

fswebcam

root@raspberrypi:/home/pi# fswebcam -r 640x480 –no-banner test_4k.jpg
--- Opening /dev/video0...
Trying source module v4l2...
/dev/video0 opened.
No input was specified, using the first.
--- Capturing frame...
Captured frame in 0.00 seconds.
--- Processing captured image...
Writing JPEG image to '–no-banner'.
Writing JPEG image to 'test_4k.jpg'.

sample code patch

  • sample 
    index 1895a6c..dbcc739 100644
--- a/docs/0002_v4l2_capture/sample/getyuyv.c
+++ b/docs/0002_v4l2_capture/sample/getyuyv.c
@@ -12,8 +12,8 @@

 #define WIDTH 640                      // 图片的宽度
 #define HEIGHT 480                     // 图片的高度
-#define FMT V4L2_PIX_FMT_YUYV          // 图片格式
-#define COUNT 5                        // 缓冲区个数
+#define FMT V4L2_PIX_FMT_MJPEG         // 图片格式
+#define COUNT 2                        // 缓冲区个数

 // int main(int argc, char **argv) {
 int main() {
@@ -112,7 +112,7 @@ int main() {
        }

        /* 第八步：从退出队列的缓冲区中获取数据并保存到文件中 */
-       FILE *fl; fl = fopen("./my.yuyv", "w");
+       FILE *fl; fl = fopen("./my.jpg", "w");
        if (NULL == fl) {
                fprintf(stderr, "open write file failed.");
        }