I'm trying to use c++ to open a raspberry pi camera using v4l2. I found several examples that follow a standard set of operations: open up the device (in my case /dev/video0) using ioctl calls query capabilities and formats set video format request a buffer query the buffer and finally mmap the buffer Everything works properly, I can open the device, query all of the capabilities and formats, set the format needed, request the buffer and query the buffer. When I try to mmap the buffer I get permission denied. Here is the call I'm using: buffer = (qint8 *)mmap(NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED, camera->handle(), buf.m.offset); This is the same as the examples that I have seen. Also, I have tried it on both the Raspberry Pi camera and on a webcam. I've checked the group and permissions for the /dev/video0 and /dev/shm and I don't see anything wrong. I even tried running my program as root with the same result. I'm obviously missing something, but I don't see what it could be. Any help would be greatly appreciated. Regards, Greg Wilson-Lindberg
