DQBUF 的 ioctl 的 V4L2 参数无效

Question

I came across a V4L2 problem.Below is the code.

v4l2_buffer queue_buf;
CLEAR(queue_buf);

queue_buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
queue_buf.memory = V4L2_MEMORY_MMAP;

if(-1 == ioctl(fd, VIDIOC_DQBUF, &queue_buf))
{
    perror("dqbuf:");
}

When run on ARM 2440 with linux 2.6.24 , arm-linux-gcc 3.4.1 , the error is "dqbuf: invalid argument".But on my PC, it works well. I don't know why it happened. thx.

Answer 1

v4l problems are very specific and I had trouble finding help myself, some time ago.

So here are some links where you should be searching for help:

• Hans de Goede and his blog . He is the programmer of the libv4l2 user space library
• v4l wiki: developer section
• v4l wiki: contact infos . I suggest you mail to the linux-media mailinglist.

I hope this helps.

regards.