1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_G_DV_TIMINGS: 5 6********************************************** 7ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS 8********************************************** 9 10Name 11==== 12 13VIDIOC_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 15Synopsis 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 34Arguments 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 43Description 44=========== 45 46To 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, 48applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing 49information is filled in using the structure struct 50:c:type:`v4l2_dv_timings`. These ioctls take a 51pointer to the struct :c:type:`v4l2_dv_timings` 52structure as argument. If the ioctl is not supported or the timing 53values are not correct, the driver returns ``EINVAL`` error code. 54 55Calling ``VIDIOC_SUBDEV_S_DV_TIMINGS`` on a subdev device node that has been 56registered in read-only mode is not allowed. An error is returned and the errno 57variable is set to ``-EPERM``. 58 59The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of 60the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If 61the 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 65Return Value 66============ 67 68On success 0 is returned, on error -1 and the ``errno`` variable is set 69appropriately. The generic error codes are described at the 70:ref:`Generic Error Codes <gen-errors>` chapter. 71 72EINVAL 73 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` 74 parameter was unsuitable. 75 76ENODATA 77 Digital video timings are not supported for this input or output. 78 79EBUSY 80 The device is busy and therefore can not change the timings. 81 82EPERM 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. 318