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 .. cpp:function:: int ioctl( int fd, int request, struct v4l2_dv_timings *argp )
25 File descriptor returned by :ref:`open() <func-open>`.
28 VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS,
29 VIDIOC_SUBDEV_G_DV_TIMINGS, VIDIOC_SUBDEV_S_DV_TIMINGS
37 To set DV timings for the input or output, applications use the
38 :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
39 applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
40 information is filled in using the structure struct
41 :ref:`v4l2_dv_timings <v4l2-dv-timings>`. These ioctls take a
42 pointer to the struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`
43 structure as argument. If the ioctl is not supported or the timing
44 values are not correct, the driver returns ``EINVAL`` error code.
46 The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
47 the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
48 the current input or output does not support DV timings (e.g. if
49 :ref:`VIDIOC_ENUMINPUT` does not set the
50 ``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.
56 On success 0 is returned, on error -1 and the ``errno`` variable is set
57 appropriately. The generic error codes are described at the
58 :ref:`Generic Error Codes <gen-errors>` chapter.
61 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>`
62 parameter was unsuitable.
65 Digital video timings are not supported for this input or output.
68 The device is busy and therefore can not change the timings.
73 .. flat-table:: struct v4l2_bt_timings
85 - Width of the active video in pixels.
93 - Height of the active video frame in lines. So for interlaced
94 formats the height of the active video in each field is
103 - Progressive (0) or interlaced (1)
111 - This is a bit mask that defines polarities of sync signals. bit 0
112 (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit
113 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If
114 the bit is set (1) it is positive polarity and if is cleared (0),
115 it is negative polarity.
123 - Pixel clock in Hz. Ex. 74.25MHz->74250000
131 - Horizontal front porch in pixels
139 - Horizontal sync length in pixels
147 - Horizontal back porch in pixels
155 - Vertical front porch in lines. For interlaced formats this refers
156 to the odd field (aka field 1).
164 - Vertical sync length in lines. For interlaced formats this refers
165 to the odd field (aka field 1).
173 - Vertical back porch in lines. For interlaced formats this refers
174 to the odd field (aka field 1).
182 - Vertical front porch in lines for the even field (aka field 2) of
183 interlaced field formats. Must be 0 for progressive formats.
191 - Vertical sync length in lines for the even field (aka field 2) of
192 interlaced field formats. Must be 0 for progressive formats.
200 - Vertical back porch in lines for the even field (aka field 2) of
201 interlaced field formats. Must be 0 for progressive formats.
209 - The video standard(s) this format belongs to. This will be filled
210 in by the driver. Applications must set this to 0. See
211 :ref:`dv-bt-standards` for a list of standards.
219 - Several flags giving more information about the format. See
220 :ref:`dv-bt-flags` for a description of the flags.
226 .. flat-table:: struct v4l2_dv_timings
239 - Type of DV timings as listed in :ref:`dv-timing-types`.
251 - struct :ref:`v4l2_bt_timings <v4l2-bt-timings>`
255 - Timings defined by BT.656/1120 specifications
270 .. flat-table:: DV Timing types
292 - ``V4L2_DV_BT_656_1120``
296 - BT.656/1120 timings
302 .. flat-table:: DV BT Timing standards
320 - ``V4L2_DV_BT_STD_CEA861``
322 - The timings follow the CEA-861 Digital TV Profile standard
326 - ``V4L2_DV_BT_STD_DMT``
328 - The timings follow the VESA Discrete Monitor Timings standard
332 - ``V4L2_DV_BT_STD_CVT``
334 - The timings follow the VESA Coordinated Video Timings standard
338 - ``V4L2_DV_BT_STD_GTF``
340 - The timings follow the VESA Generalized Timings Formula standard
346 .. flat-table:: DV BT Timing flags
364 - ``V4L2_DV_FL_REDUCED_BLANKING``
366 - CVT/GTF specific: the timings use reduced blanking (CVT) or the
367 'Secondary GTF' curve (GTF). In both cases the horizontal and/or
368 vertical blanking intervals are reduced, allowing a higher
369 resolution over the same bandwidth. This is a read-only flag,
370 applications must not set this.
374 - ``V4L2_DV_FL_CAN_REDUCE_FPS``
376 - CEA-861 specific: set for CEA-861 formats with a framerate that is
377 a multiple of six. These formats can be optionally played at 1 /
378 1.001 speed to be compatible with 60 Hz based standards such as
379 NTSC and PAL-M that use a framerate of 29.97 frames per second. If
380 the transmitter can't generate such frequencies, then the flag
381 will also be cleared. This is a read-only flag, applications must
386 - ``V4L2_DV_FL_REDUCED_FPS``
388 - CEA-861 specific: only valid for video transmitters, the flag is
389 cleared by receivers. It is also only valid for formats with the
390 ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other formats the
391 flag will be cleared by the driver. If the application sets this
392 flag, then the pixelclock used to set up the transmitter is
393 divided by 1.001 to make it compatible with NTSC framerates. If
394 the transmitter can't generate such frequencies, then the flag
395 will also be cleared.
399 - ``V4L2_DV_FL_HALF_LINE``
401 - Specific to interlaced formats: if set, then the vertical
402 frontporch of field 1 (aka the odd field) is really one half-line
403 longer and the vertical backporch of field 2 (aka the even field)
404 is really one half-line shorter, so each field has exactly the
405 same number of half-lines. Whether half-lines can be detected or
406 used depends on the hardware.
410 - ``V4L2_DV_FL_IS_CE_VIDEO``
412 - If set, then this is a Consumer Electronics (CE) video format.
413 Such formats differ from other formats (commonly called IT
414 formats) in that if R'G'B' encoding is used then by default the
415 R'G'B' values use limited range (i.e. 16-235) as opposed to full
416 range (i.e. 0-255). All formats defined in CEA-861 except for the
417 640x480p59.94 format are CE formats.