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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 86 87.. c:type:: v4l2_bt_timings 88 89.. flat-table:: struct v4l2_bt_timings 90 :header-rows: 0 91 :stub-columns: 0 92 :widths: 1 1 2 93 94 * - __u32 95 - ``width`` 96 - Width of the active video in pixels. 97 * - __u32 98 - ``height`` 99 - Height of the active video frame in lines. So for interlaced 100 formats the height of the active video in each field is 101 ``height``/2. 102 * - __u32 103 - ``interlaced`` 104 - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``). 105 * - __u32 106 - ``polarities`` 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. 112 * - __u64 113 - ``pixelclock`` 114 - Pixel clock in Hz. Ex. 74.25MHz->74250000 115 * - __u32 116 - ``hfrontporch`` 117 - Horizontal front porch in pixels 118 * - __u32 119 - ``hsync`` 120 - Horizontal sync length in pixels 121 * - __u32 122 - ``hbackporch`` 123 - Horizontal back porch in pixels 124 * - __u32 125 - ``vfrontporch`` 126 - Vertical front porch in lines. For interlaced formats this refers 127 to the odd field (aka field 1). 128 * - __u32 129 - ``vsync`` 130 - Vertical sync length in lines. For interlaced formats this refers 131 to the odd field (aka field 1). 132 * - __u32 133 - ``vbackporch`` 134 - Vertical back porch in lines. For interlaced formats this refers 135 to the odd field (aka field 1). 136 * - __u32 137 - ``il_vfrontporch`` 138 - Vertical front porch in lines for the even field (aka field 2) of 139 interlaced field formats. Must be 0 for progressive formats. 140 * - __u32 141 - ``il_vsync`` 142 - Vertical sync length in lines for the even field (aka field 2) of 143 interlaced field formats. Must be 0 for progressive formats. 144 * - __u32 145 - ``il_vbackporch`` 146 - Vertical back porch in lines for the even field (aka field 2) of 147 interlaced field formats. Must be 0 for progressive formats. 148 * - __u32 149 - ``standards`` 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. 153 * - __u32 154 - ``flags`` 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` 158 - ``picture_aspect`` 159 - The picture aspect if the pixels are not square. Only valid if the 160 ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` flag is set. 161 * - __u8 162 - ``cea861_vic`` 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. 165 * - __u8 166 - ``hdmi_vic`` 167 - The Video Identification Code according to the HDMI standard. 168 Only valid if the ``V4L2_DV_FL_HAS_HDMI_VIC`` flag is set. 169 * - __u8 170 - ``reserved[46]`` 171 - Reserved for future extensions. Drivers and applications must set 172 the array to zero. 173 174.. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.5cm}| 175 176.. c:type:: v4l2_dv_timings 177 178.. flat-table:: struct v4l2_dv_timings 179 :header-rows: 0 180 :stub-columns: 0 181 :widths: 1 1 2 182 183 * - __u32 184 - ``type`` 185 - Type of DV timings as listed in :ref:`dv-timing-types`. 186 * - union { 187 - (anonymous) 188 * - struct :c:type:`v4l2_bt_timings` 189 - ``bt`` 190 - Timings defined by BT.656/1120 specifications 191 * - __u32 192 - ``reserved``\ [32] 193 - 194 * - } 195 - 196 197.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 198 199.. _dv-timing-types: 200 201.. flat-table:: DV Timing types 202 :header-rows: 0 203 :stub-columns: 0 204 :widths: 1 1 2 205 206 * - Timing type 207 - value 208 - Description 209 * - 210 - 211 - 212 * - ``V4L2_DV_BT_656_1120`` 213 - 0 214 - BT.656/1120 timings 215 216.. tabularcolumns:: |p{4.5cm}|p{12.8cm}| 217 218.. _dv-bt-standards: 219 220.. flat-table:: DV BT Timing standards 221 :header-rows: 0 222 :stub-columns: 0 223 224 * - Timing standard 225 - Description 226 * - ``V4L2_DV_BT_STD_CEA861`` 227 - The timings follow the CEA-861 Digital TV Profile standard 228 * - ``V4L2_DV_BT_STD_DMT`` 229 - The timings follow the VESA Discrete Monitor Timings standard 230 * - ``V4L2_DV_BT_STD_CVT`` 231 - The timings follow the VESA Coordinated Video Timings standard 232 * - ``V4L2_DV_BT_STD_GTF`` 233 - The timings follow the VESA Generalized Timings Formula standard 234 * - ``V4L2_DV_BT_STD_SDI`` 235 - The timings follow the SDI Timings standard. 236 There are no horizontal syncs/porches at all in this format. 237 Total blanking timings must be set in hsync or vsync fields only. 238 239.. tabularcolumns:: |p{7.0cm}|p{10.5cm}| 240 241.. _dv-bt-flags: 242 243.. flat-table:: DV BT Timing flags 244 :header-rows: 0 245 :stub-columns: 0 246 247 * - Flag 248 - Description 249 * - ``V4L2_DV_FL_REDUCED_BLANKING`` 250 - CVT/GTF specific: the timings use reduced blanking (CVT) or the 251 'Secondary GTF' curve (GTF). In both cases the horizontal and/or 252 vertical blanking intervals are reduced, allowing a higher 253 resolution over the same bandwidth. This is a read-only flag, 254 applications must not set this. 255 * - ``V4L2_DV_FL_CAN_REDUCE_FPS`` 256 - CEA-861 specific: set for CEA-861 formats with a framerate that is 257 a multiple of six. These formats can be optionally played at 1 / 258 1.001 speed to be compatible with 60 Hz based standards such as 259 NTSC and PAL-M that use a framerate of 29.97 frames per second. If 260 the transmitter can't generate such frequencies, then the flag 261 will also be cleared. This is a read-only flag, applications must 262 not set this. 263 * - ``V4L2_DV_FL_REDUCED_FPS`` 264 - CEA-861 specific: only valid for video transmitters or video 265 receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS`` 266 set. This flag is cleared otherwise. It is also only valid for 267 formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other 268 formats the flag will be cleared by the driver. 269 270 If the application sets this flag for a transmitter, then the 271 pixelclock used to set up the transmitter is divided by 1.001 to 272 make it compatible with NTSC framerates. If the transmitter can't 273 generate such frequencies, then the flag will be cleared. 274 275 If a video receiver detects that the format uses a reduced framerate, 276 then it will set this flag to signal this to the application. 277 * - ``V4L2_DV_FL_HALF_LINE`` 278 - Specific to interlaced formats: if set, then the vertical 279 frontporch of field 1 (aka the odd field) is really one half-line 280 longer and the vertical backporch of field 2 (aka the even field) 281 is really one half-line shorter, so each field has exactly the 282 same number of half-lines. Whether half-lines can be detected or 283 used depends on the hardware. 284 * - ``V4L2_DV_FL_IS_CE_VIDEO`` 285 - If set, then this is a Consumer Electronics (CE) video format. 286 Such formats differ from other formats (commonly called IT 287 formats) in that if R'G'B' encoding is used then by default the 288 R'G'B' values use limited range (i.e. 16-235) as opposed to full 289 range (i.e. 0-255). All formats defined in CEA-861 except for the 290 640x480p59.94 format are CE formats. 291 * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE`` 292 - Some formats like SMPTE-125M have an interlaced signal with a odd 293 total height. For these formats, if this flag is set, the first 294 field has the extra line. Else, it is the second field. 295 * - ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` 296 - If set, then the picture_aspect field is valid. Otherwise assume that 297 the pixels are square, so the picture aspect ratio is the same as the 298 width to height ratio. 299 * - ``V4L2_DV_FL_HAS_CEA861_VIC`` 300 - If set, then the cea861_vic field is valid and contains the Video 301 Identification Code as per the CEA-861 standard. 302 * - ``V4L2_DV_FL_HAS_HDMI_VIC`` 303 - If set, then the hdmi_vic field is valid and contains the Video 304 Identification Code as per the HDMI standard (HDMI Vendor Specific 305 InfoFrame). 306 * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS`` 307 - CEA-861 specific: only valid for video receivers, the flag is 308 cleared by transmitters. 309 If set, then the hardware can detect the difference between 310 regular framerates and framerates reduced by 1000/1001. E.g.: 311 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz. 312