6.2.2.13. VIDEO_GET_EVENT

6.2.2.13.1. Name

VIDEO_GET_EVENT

注意

This ioctl is deprecated.

6.2.2.13.2. Synopsis

int ioctl(fd, VIDEO_GET_EVENT, struct video_event *ev)

6.2.2.13.3. Arguments

int fd	File descriptor returned by a previous call to open().
int request	Equals VIDEO_GET_EVENT for this command.
struct video_event *ev	Points to the location where the event, if any, is to be stored.

6.2.2.13.4. Description

This ioctl is for Digital TV devices only. To get events from a V4L2 decoder use the V4L2 ioctl VIDIOC_DQEVENT ioctl instead.

This ioctl call returns an event of type video_event if available. If an event is not available, the behavior depends on whether the device is in blocking or non-blocking mode. In the latter case, the call fails immediately with errno set to EWOULDBLOCK. In the former case, the call blocks until an event becomes available. The standard Linux poll() and/or select() system calls can be used with the device file descriptor to watch for new events. For select(), the file descriptor should be included in the exceptfds argument, and for poll(), POLLPRI should be specified as the wake-up condition. Read-only permissions are sufficient for this ioctl call.

video_event

struct video_event {
        __s32 type;
#define VIDEO_EVENT_SIZE_CHANGED        1
#define VIDEO_EVENT_FRAME_RATE_CHANGED  2
#define VIDEO_EVENT_DECODER_STOPPED     3
#define VIDEO_EVENT_VSYNC               4
        __kernel_time_t timestamp;
        union {
                video_size_t size;
                unsigned int frame_rate;        /* in frames per 1000sec */
                unsigned char vsync_field;      /* unknown/odd/even/progressive */
        } u;
};

6.2.2.13.5. 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.

EWOULDBLOCK	There is no event pending, and the device is in non-blocking mode.
EOVERFLOW	Overflow in event queue - one or more events were lost.