1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L
3
4 .. _VIDIOC_G_DV_TIMINGS:
5
6 **********************************************
7 ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS
8 **********************************************
9
10 Name
11 ====
12
13 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
14
15 Synopsis
16 ========
17
18 .. c:macro:: VIDIOC_G_DV_TIMINGS
19
20 ``int ioctl(int fd, VIDIOC_G_DV_TIMINGS, struct v4l2_dv_timings *argp)``
21
22 .. c:macro:: VIDIOC_S_DV_TIMINGS
23
24 ``int ioctl(int fd, VIDIOC_S_DV_TIMINGS, struct v4l2_dv_timings *argp)``
25
26 .. c:macro:: VIDIOC_SUBDEV_G_DV_TIMINGS
27
28 ``int ioctl(int fd, VIDIOC_SUBDEV_G_DV_TIMINGS, struct v4l2_dv_timings *argp)``
29
30 .. c:macro:: VIDIOC_SUBDEV_S_DV_TIMINGS
31
32 ``int ioctl(int fd, VIDIOC_SUBDEV_S_DV_TIMINGS, struct v4l2_dv_timings *argp)``
33
34 Arguments
35 =========
36
37 ``fd``
38 File descriptor returned by :c:func:`open()`.
39
40 ``argp``
41 Pointer to struct :c:type:`v4l2_dv_timings`.
42
43 Description
44 ===========
45
46 To set DV timings for the input or output, applications use the
47 :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
48 applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
49 information is filled in using the structure struct
50 :c:type:`v4l2_dv_timings`. These ioctls take a
51 pointer to the struct :c:type:`v4l2_dv_timings`
52 structure as argument. If the ioctl is not supported or the timing
53 values are not correct, the driver returns ``EINVAL`` error code.
54
55 Calling ``VIDIOC_SUBDEV_S_DV_TIMINGS`` on a subdev device node that has been
56 registered in read-only mode is not allowed. An error is returned and the errno
57 variable is set to ``-EPERM``.
58
59 The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
60 the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
61 the current input or output does not support DV timings (e.g. if
62 :ref:`VIDIOC_ENUMINPUT` does not set the
63 ``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.
64
65 Return Value
66 ============
67
68 On success 0 is returned, on error -1 and the ``errno`` variable is set
69 appropriately. The generic error codes are described at the
70 :ref:`Generic Error Codes <gen-errors>` chapter.
71
72 EINVAL
73 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>`
74 parameter was unsuitable.
75
76 ENODATA
77 Digital video timings are not supported for this input or output.
78
79 EBUSY
80 The device is busy and therefore can not change the timings.
81
82 EPERM
83 ``VIDIOC_SUBDEV_S_DV_TIMINGS`` has been called on a read-only subdevice.
84
85 .. c:type:: v4l2_bt_timings
86
87 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
88
89 .. cssclass:: longtable
90
91 .. flat-table:: struct v4l2_bt_timings
92 :header-rows: 0
93 :stub-columns: 0
94 :widths: 1 1 2
95
96 * - __u32
97 - ``width``
98 - Width of the active video in pixels.
99 * - __u32
100 - ``height``
101 - Height of the active video frame in lines. So for interlaced
102 formats the height of the active video in each field is
103 ``height``/2.
104 * - __u32
105 - ``interlaced``
106 - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``).
107 * - __u32
108 - ``polarities``
109 - This is a bit mask that defines polarities of sync signals. bit 0
110 (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit
111 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If
112 the bit is set (1) it is positive polarity and if is cleared (0),
113 it is negative polarity.
114 * - __u64
115 - ``pixelclock``
116 - Pixel clock in Hz. Ex. 74.25MHz->74250000
117 * - __u32
118 - ``hfrontporch``
119 - Horizontal front porch in pixels
120 * - __u32
121 - ``hsync``
122 - Horizontal sync length in pixels
123 * - __u32
124 - ``hbackporch``
125 - Horizontal back porch in pixels
126 * - __u32
127 - ``vfrontporch``
128 - Vertical front porch in lines. For interlaced formats this refers
129 to the odd field (aka field 1).
130 * - __u32
131 - ``vsync``
132 - Vertical sync length in lines. For interlaced formats this refers
133 to the odd field (aka field 1).
134 * - __u32
135 - ``vbackporch``
136 - Vertical back porch in lines. For interlaced formats this refers
137 to the odd field (aka field 1).
138 * - __u32
139 - ``il_vfrontporch``
140 - Vertical front porch in lines for the even field (aka field 2) of
141 interlaced field formats. Must be 0 for progressive formats.
142 * - __u32
143 - ``il_vsync``
144 - Vertical sync length in lines for the even field (aka field 2) of
145 interlaced field formats. Must be 0 for progressive formats.
146 * - __u32
147 - ``il_vbackporch``
148 - Vertical back porch in lines for the even field (aka field 2) of
149 interlaced field formats. Must be 0 for progressive formats.
150 * - __u32
151 - ``standards``
152 - The video standard(s) this format belongs to. This will be filled
153 in by the driver. Applications must set this to 0. See
154 :ref:`dv-bt-standards` for a list of standards.
155 * - __u32
156 - ``flags``
157 - Several flags giving more information about the format. See
158 :ref:`dv-bt-flags` for a description of the flags.
159 * - struct :c:type:`v4l2_fract`
160 - ``picture_aspect``
161 - The picture aspect if the pixels are not square. Only valid if the
162 ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` flag is set.
163 * - __u8
164 - ``cea861_vic``
165 - The Video Identification Code according to the CEA-861 standard.
166 Only valid if the ``V4L2_DV_FL_HAS_CEA861_VIC`` flag is set.
167 * - __u8
168 - ``hdmi_vic``
169 - The Video Identification Code according to the HDMI standard.
170 Only valid if the ``V4L2_DV_FL_HAS_HDMI_VIC`` flag is set.
171 * - __u8
172 - ``reserved[46]``
173 - Reserved for future extensions. Drivers and applications must set
174 the array to zero.
175
176 .. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.1cm}|
177
178 .. c:type:: v4l2_dv_timings
179
180 .. flat-table:: struct v4l2_dv_timings
181 :header-rows: 0
182 :stub-columns: 0
183 :widths: 1 1 2
184
185 * - __u32
186 - ``type``
187 - Type of DV timings as listed in :ref:`dv-timing-types`.
188 * - union {
189 - (anonymous)
190 * - struct :c:type:`v4l2_bt_timings`
191 - ``bt``
192 - Timings defined by BT.656/1120 specifications
193 * - __u32
194 - ``reserved``\ [32]
195 -
196 * - }
197 -
198
199 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
200
201 .. _dv-timing-types:
202
203 .. flat-table:: DV Timing types
204 :header-rows: 0
205 :stub-columns: 0
206 :widths: 1 1 2
207
208 * - Timing type
209 - value
210 - Description
211 * -
212 -
213 -
214 * - ``V4L2_DV_BT_656_1120``
215 - 0
216 - BT.656/1120 timings
217
218 .. tabularcolumns:: |p{6.5cm}|p{11.0cm}|
219
220 .. cssclass:: longtable
221
222 .. _dv-bt-standards:
223
224 .. flat-table:: DV BT Timing standards
225 :header-rows: 0
226 :stub-columns: 0
227
228 * - Timing standard
229 - Description
230 * - ``V4L2_DV_BT_STD_CEA861``
231 - The timings follow the CEA-861 Digital TV Profile standard
232 * - ``V4L2_DV_BT_STD_DMT``
233 - The timings follow the VESA Discrete Monitor Timings standard
234 * - ``V4L2_DV_BT_STD_CVT``
235 - The timings follow the VESA Coordinated Video Timings standard
236 * - ``V4L2_DV_BT_STD_GTF``
237 - The timings follow the VESA Generalized Timings Formula standard
238 * - ``V4L2_DV_BT_STD_SDI``
239 - The timings follow the SDI Timings standard.
240 There are no horizontal syncs/porches at all in this format.
241 Total blanking timings must be set in hsync or vsync fields only.
242
243 .. tabularcolumns:: |p{7.7cm}|p{9.8cm}|
244
245 .. cssclass:: longtable
246
247 .. _dv-bt-flags:
248
249 .. flat-table:: DV BT Timing flags
250 :header-rows: 0
251 :stub-columns: 0
252
253 * - Flag
254 - Description
255 * - ``V4L2_DV_FL_REDUCED_BLANKING``
256 - CVT/GTF specific: the timings use reduced blanking (CVT) or the
257 'Secondary GTF' curve (GTF). In both cases the horizontal and/or
258 vertical blanking intervals are reduced, allowing a higher
259 resolution over the same bandwidth. This is a read-only flag,
260 applications must not set this.
261 * - ``V4L2_DV_FL_CAN_REDUCE_FPS``
262 - CEA-861 specific: set for CEA-861 formats with a framerate that is
263 a multiple of six. These formats can be optionally played at 1 /
264 1.001 speed to be compatible with 60 Hz based standards such as
265 NTSC and PAL-M that use a framerate of 29.97 frames per second. If
266 the transmitter can't generate such frequencies, then the flag
267 will also be cleared. This is a read-only flag, applications must
268 not set this.
269 * - ``V4L2_DV_FL_REDUCED_FPS``
270 - CEA-861 specific: only valid for video transmitters or video
271 receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
272 set. This flag is cleared otherwise. It is also only valid for
273 formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other
274 formats the flag will be cleared by the driver.
275
276 If the application sets this flag for a transmitter, then the
277 pixelclock used to set up the transmitter is divided by 1.001 to
278 make it compatible with NTSC framerates. If the transmitter can't
279 generate such frequencies, then the flag will be cleared.
280
281 If a video receiver detects that the format uses a reduced framerate,
282 then it will set this flag to signal this to the application.
283 * - ``V4L2_DV_FL_HALF_LINE``
284 - Specific to interlaced formats: if set, then the vertical
285 frontporch of field 1 (aka the odd field) is really one half-line
286 longer and the vertical backporch of field 2 (aka the even field)
287 is really one half-line shorter, so each field has exactly the
288 same number of half-lines. Whether half-lines can be detected or
289 used depends on the hardware.
290 * - ``V4L2_DV_FL_IS_CE_VIDEO``
291 - If set, then this is a Consumer Electronics (CE) video format.
292 Such formats differ from other formats (commonly called IT
293 formats) in that if R'G'B' encoding is used then by default the
294 R'G'B' values use limited range (i.e. 16-235) as opposed to full
295 range (i.e. 0-255). All formats defined in CEA-861 except for the
296 640x480p59.94 format are CE formats.
297 * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE``
298 - Some formats like SMPTE-125M have an interlaced signal with a odd
299 total height. For these formats, if this flag is set, the first
300 field has the extra line. Else, it is the second field.
301 * - ``V4L2_DV_FL_HAS_PICTURE_ASPECT``
302 - If set, then the picture_aspect field is valid. Otherwise assume that
303 the pixels are square, so the picture aspect ratio is the same as the
304 width to height ratio.
305 * - ``V4L2_DV_FL_HAS_CEA861_VIC``
306 - If set, then the cea861_vic field is valid and contains the Video
307 Identification Code as per the CEA-861 standard.
308 * - ``V4L2_DV_FL_HAS_HDMI_VIC``
309 - If set, then the hdmi_vic field is valid and contains the Video
310 Identification Code as per the HDMI standard (HDMI Vendor Specific
311 InfoFrame).
312 * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
313 - CEA-861 specific: only valid for video receivers, the flag is
314 cleared by transmitters.
315 If set, then the hardware can detect the difference between
316 regular framerates and framerates reduced by 1000/1001. E.g.:
317 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz.
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