summaryrefslogtreecommitdiff
path: root/Documentation/media/uapi/v4l/vidioc-g-dv-timings.rst
blob: 7dd943ff14cd8b44c5ab6cc016edacf6cfd5f194 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
.. -*- coding: utf-8; mode: rst -*-

.. _VIDIOC_G_DV_TIMINGS:

**********************************************
ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS
**********************************************

Name
====

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


Synopsis
========

.. c:function:: int ioctl( int fd, VIDIOC_G_DV_TIMINGS, struct v4l2_dv_timings *argp )
    :name: VIDIOC_G_DV_TIMINGS

.. c:function:: int ioctl( int fd, VIDIOC_S_DV_TIMINGS, struct v4l2_dv_timings *argp )
    :name: VIDIOC_S_DV_TIMINGS

.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_DV_TIMINGS, struct v4l2_dv_timings *argp )
    :name: VIDIOC_SUBDEV_G_DV_TIMINGS

.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_DV_TIMINGS, struct v4l2_dv_timings *argp )
    :name: VIDIOC_SUBDEV_S_DV_TIMINGS


Arguments
=========

``fd``
    File descriptor returned by :ref:`open() <func-open>`.

``argp``


Description
===========

To set DV timings for the input or output, applications use the
:ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
information is filled in using the structure struct
:c:type:`v4l2_dv_timings`. These ioctls take a
pointer to the struct :c:type:`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.

The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
the current input or output does not support DV timings (e.g. if
:ref:`VIDIOC_ENUMINPUT` does not set the
``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.


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
:ref:`Generic Error Codes <gen-errors>` chapter.

EINVAL
    This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>`
    parameter was unsuitable.

ENODATA
    Digital video timings are not supported for this input or output.

EBUSY
    The device is busy and therefore can not change the timings.


.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|

.. c:type:: v4l2_bt_timings

.. flat-table:: struct v4l2_bt_timings
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2

    * - __u32
      - ``width``
      - Width of the active video in pixels.
    * - __u32
      - ``height``
      - Height of the active video frame in lines. So for interlaced
	formats the height of the active video in each field is
	``height``/2.
    * - __u32
      - ``interlaced``
      - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``).
    * - __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. For interlaced formats this refers
	to the odd field (aka field 1).
    * - __u32
      - ``vsync``
      - Vertical sync length in lines. For interlaced formats this refers
	to the odd field (aka field 1).
    * - __u32
      - ``vbackporch``
      - Vertical back porch in lines. For interlaced formats this refers
	to the odd field (aka field 1).
    * - __u32
      - ``il_vfrontporch``
      - Vertical front porch in lines for the even field (aka field 2) of
	interlaced field formats. Must be 0 for progressive formats.
    * - __u32
      - ``il_vsync``
      - Vertical sync length in lines for the even field (aka field 2) of
	interlaced field formats. Must be 0 for progressive formats.
    * - __u32
      - ``il_vbackporch``
      - Vertical back porch in lines for the even field (aka field 2) of
	interlaced field formats. Must be 0 for progressive formats.
    * - __u32
      - ``standards``
      - The video standard(s) this format belongs to. This will be filled
	in by the driver. Applications must set this to 0. See
	:ref:`dv-bt-standards` for a list of standards.
    * - __u32
      - ``flags``
      - Several flags giving more information about the format. See
	:ref:`dv-bt-flags` for a description of the flags.
    * - __u32
      - ``reserved[14]``
      - Reserved for future extensions. Drivers and applications must set
	the array to zero.


.. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.5cm}|

.. c:type:: v4l2_dv_timings

.. flat-table:: struct v4l2_dv_timings
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2 1

    * - __u32
      - ``type``
      -
      - Type of DV timings as listed in :ref:`dv-timing-types`.
    * - union
      -
      -
    * -
      - struct :c:type:`v4l2_bt_timings`
      - ``bt``
      - Timings defined by BT.656/1120 specifications
    * -
      - __u32
      - ``reserved``\ [32]
      -

.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|

.. _dv-timing-types:

.. flat-table:: DV Timing types
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2

    * - Timing type
      - value
      - Description
    * -
      -
      -
    * - ``V4L2_DV_BT_656_1120``
      - 0
      - BT.656/1120 timings



.. _dv-bt-standards:

.. flat-table:: DV BT Timing standards
    :header-rows:  0
    :stub-columns: 0

    * - Timing standard
      - Description
    * - ``V4L2_DV_BT_STD_CEA861``
      - The timings follow the CEA-861 Digital TV Profile standard
    * - ``V4L2_DV_BT_STD_DMT``
      - The timings follow the VESA Discrete Monitor Timings standard
    * - ``V4L2_DV_BT_STD_CVT``
      - The timings follow the VESA Coordinated Video Timings standard
    * - ``V4L2_DV_BT_STD_GTF``
      - The timings follow the VESA Generalized Timings Formula standard
    * - ``V4L2_DV_BT_STD_SDI``
      - The timings follow the SDI Timings standard.
	There are no horizontal syncs/porches at all in this format.
	Total blanking timings must be set in hsync or vsync fields only.

.. tabularcolumns:: |p{6.0cm}|p{11.5cm}|

.. _dv-bt-flags:

.. flat-table:: DV BT Timing flags
    :header-rows:  0
    :stub-columns: 0

    * - Flag
      - Description
    * - ``V4L2_DV_FL_REDUCED_BLANKING``
      - CVT/GTF specific: the timings use reduced blanking (CVT) or the
	'Secondary GTF' curve (GTF). In both cases the horizontal and/or
	vertical blanking intervals are reduced, allowing a higher
	resolution over the same bandwidth. This is a read-only flag,
	applications must not set this.
    * - ``V4L2_DV_FL_CAN_REDUCE_FPS``
      - CEA-861 specific: set for CEA-861 formats with a framerate that is
	a multiple of six. These formats can be optionally played at 1 /
	1.001 speed to be compatible with 60 Hz based standards such as
	NTSC and PAL-M that use a framerate of 29.97 frames per second. If
	the transmitter can't generate such frequencies, then the flag
	will also be cleared. This is a read-only flag, applications must
	not set this.
    * - ``V4L2_DV_FL_REDUCED_FPS``
      - CEA-861 specific: only valid for video transmitters, the flag is
	cleared by receivers. It is also only valid for formats with the
	``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other formats the
	flag will be cleared by the driver. If the application sets this
	flag, then the pixelclock used to set up the transmitter is
	divided by 1.001 to make it compatible with NTSC framerates. If
	the transmitter can't generate such frequencies, then the flag
	will also be cleared.
    * - ``V4L2_DV_FL_HALF_LINE``
      - Specific to interlaced formats: if set, then the vertical
	frontporch of field 1 (aka the odd field) is really one half-line
	longer and the vertical backporch of field 2 (aka the even field)
	is really one half-line shorter, so each field has exactly the
	same number of half-lines. Whether half-lines can be detected or
	used depends on the hardware.
    * - ``V4L2_DV_FL_IS_CE_VIDEO``
      - If set, then this is a Consumer Electronics (CE) video format.
	Such formats differ from other formats (commonly called IT
	formats) in that if R'G'B' encoding is used then by default the
	R'G'B' values use limited range (i.e. 16-235) as opposed to full
	range (i.e. 0-255). All formats defined in CEA-861 except for the
	640x480p59.94 format are CE formats.
    * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE``
      - Some formats like SMPTE-125M have an interlaced signal with a odd
	total height. For these formats, if this flag is set, the first
	field has the extra line. Else, it is the second field.