1 .. -*- coding: utf-8; mode: rst -*-
3 .. _VIDIOC_G_DV_TIMINGS:
5 **********************************************
6 ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS
7 **********************************************
12 VIDIOC_G_DV_TIMINGS - VIDIOC_S_DV_TIMINGS - VIDIOC_SUBDEV_G_DV_TIMINGS - VIDIOC_SUBDEV_S_DV_TIMINGS - Get or set DV timings for input or output
18 .. c:function:: int ioctl( int fd, VIDIOC_G_DV_TIMINGS, struct v4l2_dv_timings *argp )
19 :name: VIDIOC_G_DV_TIMINGS
21 .. c:function:: int ioctl( int fd, VIDIOC_S_DV_TIMINGS, struct v4l2_dv_timings *argp )
22 :name: VIDIOC_S_DV_TIMINGS
24 .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_DV_TIMINGS, struct v4l2_dv_timings *argp )
25 :name: VIDIOC_SUBDEV_G_DV_TIMINGS
27 .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_DV_TIMINGS, struct v4l2_dv_timings *argp )
28 :name: VIDIOC_SUBDEV_S_DV_TIMINGS
35 File descriptor returned by :ref:`open() <func-open>`.
43 To set DV timings for the input or output, applications use the
44 :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
45 applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
46 information is filled in using the structure struct
47 :ref:`v4l2_dv_timings <v4l2-dv-timings>`. These ioctls take a
48 pointer to the struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`
49 structure as argument. If the ioctl is not supported or the timing
50 values are not correct, the driver returns ``EINVAL`` error code.
52 The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
53 the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
54 the current input or output does not support DV timings (e.g. if
55 :ref:`VIDIOC_ENUMINPUT` does not set the
56 ``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.
62 On success 0 is returned, on error -1 and the ``errno`` variable is set
63 appropriately. The generic error codes are described at the
64 :ref:`Generic Error Codes <gen-errors>` chapter.
67 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>`
68 parameter was unsuitable.
71 Digital video timings are not supported for this input or output.
74 The device is busy and therefore can not change the timings.
77 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
81 .. flat-table:: struct v4l2_bt_timings
93 - Width of the active video in pixels.
101 - Height of the active video frame in lines. So for interlaced
102 formats the height of the active video in each field is
111 - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``).
119 - This is a bit mask that defines polarities of sync signals. bit 0
120 (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit
121 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If
122 the bit is set (1) it is positive polarity and if is cleared (0),
123 it is negative polarity.
131 - Pixel clock in Hz. Ex. 74.25MHz->74250000
139 - Horizontal front porch in pixels
147 - Horizontal sync length in pixels
155 - Horizontal back porch in pixels
163 - Vertical front porch in lines. For interlaced formats this refers
164 to the odd field (aka field 1).
172 - Vertical sync length in lines. For interlaced formats this refers
173 to the odd field (aka field 1).
181 - Vertical back porch in lines. For interlaced formats this refers
182 to the odd field (aka field 1).
190 - Vertical front porch in lines for the even field (aka field 2) of
191 interlaced field formats. Must be 0 for progressive formats.
199 - Vertical sync length in lines for the even field (aka field 2) of
200 interlaced field formats. Must be 0 for progressive formats.
208 - Vertical back porch in lines for the even field (aka field 2) of
209 interlaced field formats. Must be 0 for progressive formats.
217 - The video standard(s) this format belongs to. This will be filled
218 in by the driver. Applications must set this to 0. See
219 :ref:`dv-bt-standards` for a list of standards.
227 - Several flags giving more information about the format. See
228 :ref:`dv-bt-flags` for a description of the flags.
232 .. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.5cm}|
236 .. flat-table:: struct v4l2_dv_timings
249 - Type of DV timings as listed in :ref:`dv-timing-types`.
261 - struct :ref:`v4l2_bt_timings <v4l2-bt-timings>`
265 - Timings defined by BT.656/1120 specifications
276 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
280 .. flat-table:: DV Timing types
302 - ``V4L2_DV_BT_656_1120``
306 - BT.656/1120 timings
312 .. flat-table:: DV BT Timing standards
325 - ``V4L2_DV_BT_STD_CEA861``
327 - The timings follow the CEA-861 Digital TV Profile standard
331 - ``V4L2_DV_BT_STD_DMT``
333 - The timings follow the VESA Discrete Monitor Timings standard
337 - ``V4L2_DV_BT_STD_CVT``
339 - The timings follow the VESA Coordinated Video Timings standard
343 - ``V4L2_DV_BT_STD_GTF``
345 - The timings follow the VESA Generalized Timings Formula standard
348 .. tabularcolumns:: |p{6.0cm}|p{11.5cm}|
352 .. flat-table:: DV BT Timing flags
365 - ``V4L2_DV_FL_REDUCED_BLANKING``
367 - CVT/GTF specific: the timings use reduced blanking (CVT) or the
368 'Secondary GTF' curve (GTF). In both cases the horizontal and/or
369 vertical blanking intervals are reduced, allowing a higher
370 resolution over the same bandwidth. This is a read-only flag,
371 applications must not set this.
375 - ``V4L2_DV_FL_CAN_REDUCE_FPS``
377 - CEA-861 specific: set for CEA-861 formats with a framerate that is
378 a multiple of six. These formats can be optionally played at 1 /
379 1.001 speed to be compatible with 60 Hz based standards such as
380 NTSC and PAL-M that use a framerate of 29.97 frames per second. If
381 the transmitter can't generate such frequencies, then the flag
382 will also be cleared. This is a read-only flag, applications must
387 - ``V4L2_DV_FL_REDUCED_FPS``
389 - CEA-861 specific: only valid for video transmitters, the flag is
390 cleared by receivers. It is also only valid for formats with the
391 ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other formats the
392 flag will be cleared by the driver. If the application sets this
393 flag, then the pixelclock used to set up the transmitter is
394 divided by 1.001 to make it compatible with NTSC framerates. If
395 the transmitter can't generate such frequencies, then the flag
396 will also be cleared.
400 - ``V4L2_DV_FL_HALF_LINE``
402 - Specific to interlaced formats: if set, then the vertical
403 frontporch of field 1 (aka the odd field) is really one half-line
404 longer and the vertical backporch of field 2 (aka the even field)
405 is really one half-line shorter, so each field has exactly the
406 same number of half-lines. Whether half-lines can be detected or
407 used depends on the hardware.
411 - ``V4L2_DV_FL_IS_CE_VIDEO``
413 - If set, then this is a Consumer Electronics (CE) video format.
414 Such formats differ from other formats (commonly called IT
415 formats) in that if R'G'B' encoding is used then by default the
416 R'G'B' values use limited range (i.e. 16-235) as opposed to full
417 range (i.e. 0-255). All formats defined in CEA-861 except for the
418 640x480p59.94 format are CE formats.