VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS — Get or set custom DV timings for input or output
int ioctl( | int fd, |
| int request, | |
struct v4l2_dv_timings *argp); |
To set custom DV timings for the input or output, applications use the
VIDIOC_S_DV_TIMINGS ioctl and to get the current custom timings,
applications use the VIDIOC_G_DV_TIMINGS ioctl. The detailed timing
information is filled in using the structure struct v4l2_dv_timings. These ioctls take
a pointer to the struct v4l2_dv_timings structure as argument. If the ioctl is not supported
or the timing values are not correct, the driver returns EINVAL error code.
On success 0 is returned, on error -1 and the errno variable is set appropriately:
This ioctl is not supported, or the
VIDIOC_S_DV_TIMINGS parameter was unsuitable.
The device is busy and therefore can not change the timings.
Table A.43. struct v4l2_bt_timings
| __u32 | width | Width of the active video in pixels |
| __u32 | height | Height of the active video in lines |
| __u32 | interlaced | Progressive (0) or interlaced (1) |
| __u32 | polarities | This is a bit mask that defines polarities of sync signals. bit 0 (V4L2_DV_VSYNC_POS_POL) is for vertical sync polarity and bit 1 (V4L2_DV_HSYNC_POS_POL) is for horizontal sync polarity. If the bit is set (1) it is positive polarity and if is cleared (0), it is negative polarity. |
| __u64 | pixelclock | Pixel clock in Hz. Ex. 74.25MHz->74250000 |
| __u32 | hfrontporch | Horizontal front porch in pixels |
| __u32 | hsync | Horizontal sync length in pixels |
| __u32 | hbackporch | Horizontal back porch in pixels |
| __u32 | vfrontporch | Vertical front porch in lines |
| __u32 | vsync | Vertical sync length in lines |
| __u32 | vbackporch | Vertical back porch in lines |
| __u32 | il_vfrontporch | Vertical front porch in lines for bottom field of interlaced field formats |
| __u32 | il_vsync | Vertical sync length in lines for bottom field of interlaced field formats |
| __u32 | il_vbackporch | Vertical back porch in lines for bottom field of interlaced field formats |
Table A.44. struct v4l2_dv_timings
| __u32 | type | Type of DV timings as listed in Table A.45, “DV Timing types”. | |
| union | | ||
| struct v4l2_bt_timings | bt | Timings defined by BT.656/1120 specifications | |
| __u32 | reserved[32] |