Automatically detect camera capable v4l2 device.

[apps/camera-gstreamer.git] / app / utils.cpp

diff --git a/app/utils.cpp b/app/utils.cpp
index f1c3eae..1cf71f2 100644 (file)
--- a/app/utils.cpp
+++ b/app/utils.cpp
@@ -1,10 +1,16 @@
 #include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <dirent.h>
 #include <assert.h>
 #include <cstdlib>
 #include <cstring>
 #include <cerrno>
+#include <cstdio>
+#include <cctype>
+#include <linux/videodev2.h>
 
 #include "utils.h"
 
@@ -148,3 +154,44 @@ os_create_anonymous_file(off_t size)
 
        return fd;
 }
+
+const char*
+get_camera_device(void)
+{
+       DIR *dir = opendir("/dev");
+       if (!dir) {
+               perror("Couldn't open the '/dev' directory");
+               return NULL;
+       }
+
+       static char device[PATH_MAX];
+       bool found = false;
+       while (struct dirent *dirent = readdir(dir)) {
+               if (strncmp(dirent->d_name, "video", strlen("video")))
+                       continue;
+               if (!isdigit(dirent->d_name[strlen("video")]))
+                       continue;
+
+               strcpy(device, "/dev/");
+               strncat(device, dirent->d_name, sizeof(device) - 1);
+
+               int fd = open(device, O_RDWR);
+               if (fd == -1)
+                       continue;
+               struct v4l2_capability vid_cap;
+               if (ioctl(fd, VIDIOC_QUERYCAP, &vid_cap) < 0) {
+                       close(fd);
+                       continue;
+               }
+               close(fd);
+
+               if ((vid_cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) ||
+                       (vid_cap.capabilities & V4L2_CAP_VIDEO_CAPTURE_MPLANE)) {
+                       found = true;
+                       break;
+               }
+       }
+
+       closedir(dir);
+       return found ? device : NULL;
+}