7.36. ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT¶
VIDIOC_G_OUTPUT - VIDIOC_S_OUTPUT - Query or select the current video output
int ioctl(int fd, VIDIOC_G_OUTPUT, int *argp)
int ioctl(int fd, VIDIOC_S_OUTPUT, int *argp)
File descriptor returned by
Pointer to an integer with output index.
To query the current video output applications call the
VIDIOC_G_OUTPUT ioctl with a pointer to an integer where the driver
stores the number of the output, as in the struct
index field. This ioctl will
fail only when there are no video outputs, returning the
To select a video output applications store the number of the desired output in an integer and call the VIDIOC_S_OUTPUT ioctl with a pointer to this integer. Side effects are possible. For example outputs may support different video standards, so the driver may implicitly switch the current standard. Because of these possible side effects applications must select an output before querying or negotiating any other parameters.
Information about video outputs is available using the ioctl VIDIOC_ENUMOUTPUT ioctl.
7.36.5. Return Value¶
On success 0 is returned, on error -1 and the
errno variable is set
appropriately. The generic error codes are described at the
Generic Error Codes chapter.
The number of the video output is out of bounds, or there are no video outputs at all.