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>`.
38 Pointer to struct :c:type:`v4l2_dv_timings`.
44 To set DV timings for the input or output, applications use the
45 :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
46 applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
47 information is filled in using the structure struct
48 :c:type:`v4l2_dv_timings`. These ioctls take a
49 pointer to the struct :c:type:`v4l2_dv_timings`
50 structure as argument. If the ioctl is not supported or the timing
51 values are not correct, the driver returns ``EINVAL`` error code.
53 The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
54 the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
55 the current input or output does not support DV timings (e.g. if
56 :ref:`VIDIOC_ENUMINPUT` does not set the
57 ``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.
63 On success 0 is returned, on error -1 and the ``errno`` variable is set
64 appropriately. The generic error codes are described at the
65 :ref:`Generic Error Codes <gen-errors>` chapter.
68 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>`
69 parameter was unsuitable.
72 Digital video timings are not supported for this input or output.
75 The device is busy and therefore can not change the timings.
78 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
80 .. c:type:: v4l2_bt_timings
82 .. flat-table:: struct v4l2_bt_timings
89 - Width of the active video in pixels.
92 - Height of the active video frame in lines. So for interlaced
93 formats the height of the active video in each field is
97 - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``).
100 - This is a bit mask that defines polarities of sync signals. bit 0
101 (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit
102 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If
103 the bit is set (1) it is positive polarity and if is cleared (0),
104 it is negative polarity.
107 - Pixel clock in Hz. Ex. 74.25MHz->74250000
110 - Horizontal front porch in pixels
113 - Horizontal sync length in pixels
116 - Horizontal back porch in pixels
119 - Vertical front porch in lines. For interlaced formats this refers
120 to the odd field (aka field 1).
123 - Vertical sync length in lines. For interlaced formats this refers
124 to the odd field (aka field 1).
127 - Vertical back porch in lines. For interlaced formats this refers
128 to the odd field (aka field 1).
131 - Vertical front porch in lines for the even field (aka field 2) of
132 interlaced field formats. Must be 0 for progressive formats.
135 - Vertical sync length in lines for the even field (aka field 2) of
136 interlaced field formats. Must be 0 for progressive formats.
139 - Vertical back porch in lines for the even field (aka field 2) of
140 interlaced field formats. Must be 0 for progressive formats.
143 - The video standard(s) this format belongs to. This will be filled
144 in by the driver. Applications must set this to 0. See
145 :ref:`dv-bt-standards` for a list of standards.
148 - Several flags giving more information about the format. See
149 :ref:`dv-bt-flags` for a description of the flags.
150 * - struct :c:type:`v4l2_fract`
152 - The picture aspect if the pixels are not square. Only valid if the
153 ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` flag is set.
156 - The Video Identification Code according to the CEA-861 standard.
157 Only valid if the ``V4L2_DV_FL_HAS_CEA861_VIC`` flag is set.
160 - The Video Identification Code according to the HDMI standard.
161 Only valid if the ``V4L2_DV_FL_HAS_HDMI_VIC`` flag is set.
164 - Reserved for future extensions. Drivers and applications must set
168 .. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.5cm}|
170 .. c:type:: v4l2_dv_timings
172 .. flat-table:: struct v4l2_dv_timings
180 - Type of DV timings as listed in :ref:`dv-timing-types`.
185 - struct :c:type:`v4l2_bt_timings`
187 - Timings defined by BT.656/1120 specifications
193 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
197 .. flat-table:: DV Timing types
208 * - ``V4L2_DV_BT_656_1120``
210 - BT.656/1120 timings
212 .. tabularcolumns:: |p{4.5cm}|p{12.8cm}|
216 .. flat-table:: DV BT Timing standards
222 * - ``V4L2_DV_BT_STD_CEA861``
223 - The timings follow the CEA-861 Digital TV Profile standard
224 * - ``V4L2_DV_BT_STD_DMT``
225 - The timings follow the VESA Discrete Monitor Timings standard
226 * - ``V4L2_DV_BT_STD_CVT``
227 - The timings follow the VESA Coordinated Video Timings standard
228 * - ``V4L2_DV_BT_STD_GTF``
229 - The timings follow the VESA Generalized Timings Formula standard
230 * - ``V4L2_DV_BT_STD_SDI``
231 - The timings follow the SDI Timings standard.
232 There are no horizontal syncs/porches at all in this format.
233 Total blanking timings must be set in hsync or vsync fields only.
235 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
239 .. flat-table:: DV BT Timing flags
245 * - ``V4L2_DV_FL_REDUCED_BLANKING``
246 - CVT/GTF specific: the timings use reduced blanking (CVT) or the
247 'Secondary GTF' curve (GTF). In both cases the horizontal and/or
248 vertical blanking intervals are reduced, allowing a higher
249 resolution over the same bandwidth. This is a read-only flag,
250 applications must not set this.
251 * - ``V4L2_DV_FL_CAN_REDUCE_FPS``
252 - CEA-861 specific: set for CEA-861 formats with a framerate that is
253 a multiple of six. These formats can be optionally played at 1 /
254 1.001 speed to be compatible with 60 Hz based standards such as
255 NTSC and PAL-M that use a framerate of 29.97 frames per second. If
256 the transmitter can't generate such frequencies, then the flag
257 will also be cleared. This is a read-only flag, applications must
259 * - ``V4L2_DV_FL_REDUCED_FPS``
260 - CEA-861 specific: only valid for video transmitters or video
261 receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
262 set. This flag is cleared otherwise. It is also only valid for
263 formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other
264 formats the flag will be cleared by the driver.
266 If the application sets this flag for a transmitter, then the
267 pixelclock used to set up the transmitter is divided by 1.001 to
268 make it compatible with NTSC framerates. If the transmitter can't
269 generate such frequencies, then the flag will be cleared.
271 If a video receiver detects that the format uses a reduced framerate,
272 then it will set this flag to signal this to the application.
273 * - ``V4L2_DV_FL_HALF_LINE``
274 - Specific to interlaced formats: if set, then the vertical
275 backporch of field 1 (aka the odd field) is really one half-line
276 longer and the vertical backporch of field 2 (aka the even field)
277 is really one half-line shorter, so each field has exactly the
278 same number of half-lines. Whether half-lines can be detected or
279 used depends on the hardware.
280 * - ``V4L2_DV_FL_IS_CE_VIDEO``
281 - If set, then this is a Consumer Electronics (CE) video format.
282 Such formats differ from other formats (commonly called IT
283 formats) in that if R'G'B' encoding is used then by default the
284 R'G'B' values use limited range (i.e. 16-235) as opposed to full
285 range (i.e. 0-255). All formats defined in CEA-861 except for the
286 640x480p59.94 format are CE formats.
287 * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE``
288 - Some formats like SMPTE-125M have an interlaced signal with a odd
289 total height. For these formats, if this flag is set, the first
290 field has the extra line. Else, it is the second field.
291 * - ``V4L2_DV_FL_HAS_PICTURE_ASPECT``
292 - If set, then the picture_aspect field is valid. Otherwise assume that
293 the pixels are square, so the picture aspect ratio is the same as the
294 width to height ratio.
295 * - ``V4L2_DV_FL_HAS_CEA861_VIC``
296 - If set, then the cea861_vic field is valid and contains the Video
297 Identification Code as per the CEA-861 standard.
298 * - ``V4L2_DV_FL_HAS_HDMI_VIC``
299 - If set, then the hdmi_vic field is valid and contains the Video
300 Identification Code as per the HDMI standard (HDMI Vendor Specific
302 * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
303 - CEA-861 specific: only valid for video receivers, the flag is
304 cleared by transmitters.
305 If set, then the hardware can detect the difference between
306 regular framerates and framerates reduced by 1000/1001. E.g.:
307 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz.