Hi, after reading the v4l2 specs there are some questions remaining. To capture some frames, I have to code the following from the application side (ioctls in CAPITALS, else system calls ) // after open(), setting the format etc. do this VIDIOC_REQBUFS - to request some buffers for grabbing VIDIOC_QUERYBUF - query evry buffer and do the appropriate (enque for example) mmap - map driver buffers to user space VIDIOC_QBUF -enque every buffer for the driver if necessary VIDIOC_STREAMON - begin to grab in enqued buffers Q: What if no buffers are enqued by the app ? VIDIOC_DQBUF -deque buffer to do some user space operations Q1: Does DQBUF block, when the hardware is just capturing in this buffer, until capturing has finished ? Q2: Is there any way to get the last captured buffer (and skip the other buffers)? Q3: What should the driver do, if the application wants to deque the last buffer ? If streaming is going on, the hardware need at least one buffer, or the streaming has to be stopped. VIDIOC_QBUF - enque again // If enough frames are captured finally do this VIDIOC_STREAMOFF - stop to grab munmap Q: To restart capturing, do I have to start @ VIDIOC_REQBUFS again ? TIA, Franz
