1 .. Permission is granted to copy, distribute and/or modify this
2 .. document under the terms of the GNU Free Documentation License,
3 .. Version 1.1 or any later version published by the Free Software
4 .. Foundation, with no Invariant Sections, no Front-Cover Texts
5 .. and no Back-Cover Texts. A copy of the license is included at
6 .. Documentation/media/uapi/fdl-appendix.rst.
8 .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
10 .. _VIDIOC_G_DV_TIMINGS:
12 **********************************************
13 ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS
14 **********************************************
19 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
25 .. c:function:: int ioctl( int fd, VIDIOC_G_DV_TIMINGS, struct v4l2_dv_timings *argp )
26 :name: VIDIOC_G_DV_TIMINGS
28 .. c:function:: int ioctl( int fd, VIDIOC_S_DV_TIMINGS, struct v4l2_dv_timings *argp )
29 :name: VIDIOC_S_DV_TIMINGS
31 .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_DV_TIMINGS, struct v4l2_dv_timings *argp )
32 :name: VIDIOC_SUBDEV_G_DV_TIMINGS
34 .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_DV_TIMINGS, struct v4l2_dv_timings *argp )
35 :name: VIDIOC_SUBDEV_S_DV_TIMINGS
42 File descriptor returned by :ref:`open() <func-open>`.
45 Pointer to struct :c:type:`v4l2_dv_timings`.
51 To set DV timings for the input or output, applications use the
52 :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings,
53 applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing
54 information is filled in using the structure struct
55 :c:type:`v4l2_dv_timings`. These ioctls take a
56 pointer to the struct :c:type:`v4l2_dv_timings`
57 structure as argument. If the ioctl is not supported or the timing
58 values are not correct, the driver returns ``EINVAL`` error code.
60 The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of
61 the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If
62 the current input or output does not support DV timings (e.g. if
63 :ref:`VIDIOC_ENUMINPUT` does not set the
64 ``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned.
70 On success 0 is returned, on error -1 and the ``errno`` variable is set
71 appropriately. The generic error codes are described at the
72 :ref:`Generic Error Codes <gen-errors>` chapter.
75 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>`
76 parameter was unsuitable.
79 Digital video timings are not supported for this input or output.
82 The device is busy and therefore can not change the timings.
85 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
87 .. c:type:: v4l2_bt_timings
89 .. flat-table:: struct v4l2_bt_timings
96 - Width of the active video in pixels.
99 - Height of the active video frame in lines. So for interlaced
100 formats the height of the active video in each field is
104 - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``).
107 - This is a bit mask that defines polarities of sync signals. bit 0
108 (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit
109 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If
110 the bit is set (1) it is positive polarity and if is cleared (0),
111 it is negative polarity.
114 - Pixel clock in Hz. Ex. 74.25MHz->74250000
117 - Horizontal front porch in pixels
120 - Horizontal sync length in pixels
123 - Horizontal back porch in pixels
126 - Vertical front porch in lines. For interlaced formats this refers
127 to the odd field (aka field 1).
130 - Vertical sync length in lines. For interlaced formats this refers
131 to the odd field (aka field 1).
134 - Vertical back porch in lines. For interlaced formats this refers
135 to the odd field (aka field 1).
138 - Vertical front porch in lines for the even field (aka field 2) of
139 interlaced field formats. Must be 0 for progressive formats.
142 - Vertical sync length in lines for the even field (aka field 2) of
143 interlaced field formats. Must be 0 for progressive formats.
146 - Vertical back porch in lines for the even field (aka field 2) of
147 interlaced field formats. Must be 0 for progressive formats.
150 - The video standard(s) this format belongs to. This will be filled
151 in by the driver. Applications must set this to 0. See
152 :ref:`dv-bt-standards` for a list of standards.
155 - Several flags giving more information about the format. See
156 :ref:`dv-bt-flags` for a description of the flags.
157 * - struct :c:type:`v4l2_fract`
159 - The picture aspect if the pixels are not square. Only valid if the
160 ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` flag is set.
163 - The Video Identification Code according to the CEA-861 standard.
164 Only valid if the ``V4L2_DV_FL_HAS_CEA861_VIC`` flag is set.
167 - The Video Identification Code according to the HDMI standard.
168 Only valid if the ``V4L2_DV_FL_HAS_HDMI_VIC`` flag is set.
171 - Reserved for future extensions. Drivers and applications must set
175 .. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.5cm}|
177 .. c:type:: v4l2_dv_timings
179 .. flat-table:: struct v4l2_dv_timings
186 - Type of DV timings as listed in :ref:`dv-timing-types`.
189 * - struct :c:type:`v4l2_bt_timings`
191 - Timings defined by BT.656/1120 specifications
198 .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
202 .. flat-table:: DV Timing types
213 * - ``V4L2_DV_BT_656_1120``
215 - BT.656/1120 timings
217 .. tabularcolumns:: |p{4.5cm}|p{12.8cm}|
221 .. flat-table:: DV BT Timing standards
227 * - ``V4L2_DV_BT_STD_CEA861``
228 - The timings follow the CEA-861 Digital TV Profile standard
229 * - ``V4L2_DV_BT_STD_DMT``
230 - The timings follow the VESA Discrete Monitor Timings standard
231 * - ``V4L2_DV_BT_STD_CVT``
232 - The timings follow the VESA Coordinated Video Timings standard
233 * - ``V4L2_DV_BT_STD_GTF``
234 - The timings follow the VESA Generalized Timings Formula standard
235 * - ``V4L2_DV_BT_STD_SDI``
236 - The timings follow the SDI Timings standard.
237 There are no horizontal syncs/porches at all in this format.
238 Total blanking timings must be set in hsync or vsync fields only.
240 .. tabularcolumns:: |p{7.0cm}|p{10.5cm}|
244 .. flat-table:: DV BT Timing flags
250 * - ``V4L2_DV_FL_REDUCED_BLANKING``
251 - CVT/GTF specific: the timings use reduced blanking (CVT) or the
252 'Secondary GTF' curve (GTF). In both cases the horizontal and/or
253 vertical blanking intervals are reduced, allowing a higher
254 resolution over the same bandwidth. This is a read-only flag,
255 applications must not set this.
256 * - ``V4L2_DV_FL_CAN_REDUCE_FPS``
257 - CEA-861 specific: set for CEA-861 formats with a framerate that is
258 a multiple of six. These formats can be optionally played at 1 /
259 1.001 speed to be compatible with 60 Hz based standards such as
260 NTSC and PAL-M that use a framerate of 29.97 frames per second. If
261 the transmitter can't generate such frequencies, then the flag
262 will also be cleared. This is a read-only flag, applications must
264 * - ``V4L2_DV_FL_REDUCED_FPS``
265 - CEA-861 specific: only valid for video transmitters or video
266 receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
267 set. This flag is cleared otherwise. It is also only valid for
268 formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other
269 formats the flag will be cleared by the driver.
271 If the application sets this flag for a transmitter, then the
272 pixelclock used to set up the transmitter is divided by 1.001 to
273 make it compatible with NTSC framerates. If the transmitter can't
274 generate such frequencies, then the flag will be cleared.
276 If a video receiver detects that the format uses a reduced framerate,
277 then it will set this flag to signal this to the application.
278 * - ``V4L2_DV_FL_HALF_LINE``
279 - Specific to interlaced formats: if set, then the vertical
280 frontporch of field 1 (aka the odd field) is really one half-line
281 longer and the vertical backporch of field 2 (aka the even field)
282 is really one half-line shorter, so each field has exactly the
283 same number of half-lines. Whether half-lines can be detected or
284 used depends on the hardware.
285 * - ``V4L2_DV_FL_IS_CE_VIDEO``
286 - If set, then this is a Consumer Electronics (CE) video format.
287 Such formats differ from other formats (commonly called IT
288 formats) in that if R'G'B' encoding is used then by default the
289 R'G'B' values use limited range (i.e. 16-235) as opposed to full
290 range (i.e. 0-255). All formats defined in CEA-861 except for the
291 640x480p59.94 format are CE formats.
292 * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE``
293 - Some formats like SMPTE-125M have an interlaced signal with a odd
294 total height. For these formats, if this flag is set, the first
295 field has the extra line. Else, it is the second field.
296 * - ``V4L2_DV_FL_HAS_PICTURE_ASPECT``
297 - If set, then the picture_aspect field is valid. Otherwise assume that
298 the pixels are square, so the picture aspect ratio is the same as the
299 width to height ratio.
300 * - ``V4L2_DV_FL_HAS_CEA861_VIC``
301 - If set, then the cea861_vic field is valid and contains the Video
302 Identification Code as per the CEA-861 standard.
303 * - ``V4L2_DV_FL_HAS_HDMI_VIC``
304 - If set, then the hdmi_vic field is valid and contains the Video
305 Identification Code as per the HDMI standard (HDMI Vendor Specific
307 * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS``
308 - CEA-861 specific: only valid for video receivers, the flag is
309 cleared by transmitters.
310 If set, then the hardware can detect the difference between
311 regular framerates and framerates reduced by 1000/1001. E.g.:
312 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz.