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/userspace-api/media/fdl-appendix.rst. 7.. 8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections 9 10.. _VIDIOC_G_DV_TIMINGS: 11 12********************************************** 13ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS 14********************************************** 15 16Name 17==== 18 19VIDIOC_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 20 21 22Synopsis 23======== 24 25.. c:function:: int ioctl( int fd, VIDIOC_G_DV_TIMINGS, struct v4l2_dv_timings *argp ) 26 :name: VIDIOC_G_DV_TIMINGS 27 28.. c:function:: int ioctl( int fd, VIDIOC_S_DV_TIMINGS, struct v4l2_dv_timings *argp ) 29 :name: VIDIOC_S_DV_TIMINGS 30 31.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_DV_TIMINGS, struct v4l2_dv_timings *argp ) 32 :name: VIDIOC_SUBDEV_G_DV_TIMINGS 33 34.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_DV_TIMINGS, struct v4l2_dv_timings *argp ) 35 :name: VIDIOC_SUBDEV_S_DV_TIMINGS 36 37 38Arguments 39========= 40 41``fd`` 42 File descriptor returned by :ref:`open() <func-open>`. 43 44``argp`` 45 Pointer to struct :c:type:`v4l2_dv_timings`. 46 47 48Description 49=========== 50 51To 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, 53applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing 54information is filled in using the structure struct 55:c:type:`v4l2_dv_timings`. These ioctls take a 56pointer to the struct :c:type:`v4l2_dv_timings` 57structure as argument. If the ioctl is not supported or the timing 58values are not correct, the driver returns ``EINVAL`` error code. 59 60Calling ``VIDIOC_SUBDEV_S_DV_TIMINGS`` on a subdev device node that has been 61registered in read-only mode is not allowed. An error is returned and the errno 62variable is set to ``-EPERM``. 63 64The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of 65the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If 66the current input or output does not support DV timings (e.g. if 67:ref:`VIDIOC_ENUMINPUT` does not set the 68``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned. 69 70 71Return Value 72============ 73 74On success 0 is returned, on error -1 and the ``errno`` variable is set 75appropriately. The generic error codes are described at the 76:ref:`Generic Error Codes <gen-errors>` chapter. 77 78EINVAL 79 This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` 80 parameter was unsuitable. 81 82ENODATA 83 Digital video timings are not supported for this input or output. 84 85EBUSY 86 The device is busy and therefore can not change the timings. 87 88EPERM 89 ``VIDIOC_SUBDEV_S_DV_TIMINGS`` has been called on a read-only subdevice. 90 91.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 92 93.. c:type:: v4l2_bt_timings 94 95.. flat-table:: struct v4l2_bt_timings 96 :header-rows: 0 97 :stub-columns: 0 98 :widths: 1 1 2 99 100 * - __u32 101 - ``width`` 102 - Width of the active video in pixels. 103 * - __u32 104 - ``height`` 105 - Height of the active video frame in lines. So for interlaced 106 formats the height of the active video in each field is 107 ``height``/2. 108 * - __u32 109 - ``interlaced`` 110 - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``). 111 * - __u32 112 - ``polarities`` 113 - This is a bit mask that defines polarities of sync signals. bit 0 114 (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit 115 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If 116 the bit is set (1) it is positive polarity and if is cleared (0), 117 it is negative polarity. 118 * - __u64 119 - ``pixelclock`` 120 - Pixel clock in Hz. Ex. 74.25MHz->74250000 121 * - __u32 122 - ``hfrontporch`` 123 - Horizontal front porch in pixels 124 * - __u32 125 - ``hsync`` 126 - Horizontal sync length in pixels 127 * - __u32 128 - ``hbackporch`` 129 - Horizontal back porch in pixels 130 * - __u32 131 - ``vfrontporch`` 132 - Vertical front porch in lines. For interlaced formats this refers 133 to the odd field (aka field 1). 134 * - __u32 135 - ``vsync`` 136 - Vertical sync length in lines. For interlaced formats this refers 137 to the odd field (aka field 1). 138 * - __u32 139 - ``vbackporch`` 140 - Vertical back porch in lines. For interlaced formats this refers 141 to the odd field (aka field 1). 142 * - __u32 143 - ``il_vfrontporch`` 144 - Vertical front porch in lines for the even field (aka field 2) of 145 interlaced field formats. Must be 0 for progressive formats. 146 * - __u32 147 - ``il_vsync`` 148 - Vertical sync length in lines for the even field (aka field 2) of 149 interlaced field formats. Must be 0 for progressive formats. 150 * - __u32 151 - ``il_vbackporch`` 152 - Vertical back porch in lines for the even field (aka field 2) of 153 interlaced field formats. Must be 0 for progressive formats. 154 * - __u32 155 - ``standards`` 156 - The video standard(s) this format belongs to. This will be filled 157 in by the driver. Applications must set this to 0. See 158 :ref:`dv-bt-standards` for a list of standards. 159 * - __u32 160 - ``flags`` 161 - Several flags giving more information about the format. See 162 :ref:`dv-bt-flags` for a description of the flags. 163 * - struct :c:type:`v4l2_fract` 164 - ``picture_aspect`` 165 - The picture aspect if the pixels are not square. Only valid if the 166 ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` flag is set. 167 * - __u8 168 - ``cea861_vic`` 169 - The Video Identification Code according to the CEA-861 standard. 170 Only valid if the ``V4L2_DV_FL_HAS_CEA861_VIC`` flag is set. 171 * - __u8 172 - ``hdmi_vic`` 173 - The Video Identification Code according to the HDMI standard. 174 Only valid if the ``V4L2_DV_FL_HAS_HDMI_VIC`` flag is set. 175 * - __u8 176 - ``reserved[46]`` 177 - Reserved for future extensions. Drivers and applications must set 178 the array to zero. 179 180 181.. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.5cm}| 182 183.. c:type:: v4l2_dv_timings 184 185.. flat-table:: struct v4l2_dv_timings 186 :header-rows: 0 187 :stub-columns: 0 188 :widths: 1 1 2 189 190 * - __u32 191 - ``type`` 192 - Type of DV timings as listed in :ref:`dv-timing-types`. 193 * - union { 194 - (anonymous) 195 * - struct :c:type:`v4l2_bt_timings` 196 - ``bt`` 197 - Timings defined by BT.656/1120 specifications 198 * - __u32 199 - ``reserved``\ [32] 200 - 201 * - } 202 - 203 204.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| 205 206.. _dv-timing-types: 207 208.. flat-table:: DV Timing types 209 :header-rows: 0 210 :stub-columns: 0 211 :widths: 1 1 2 212 213 * - Timing type 214 - value 215 - Description 216 * - 217 - 218 - 219 * - ``V4L2_DV_BT_656_1120`` 220 - 0 221 - BT.656/1120 timings 222 223.. tabularcolumns:: |p{4.5cm}|p{12.8cm}| 224 225.. _dv-bt-standards: 226 227.. flat-table:: DV BT Timing standards 228 :header-rows: 0 229 :stub-columns: 0 230 231 * - Timing standard 232 - Description 233 * - ``V4L2_DV_BT_STD_CEA861`` 234 - The timings follow the CEA-861 Digital TV Profile standard 235 * - ``V4L2_DV_BT_STD_DMT`` 236 - The timings follow the VESA Discrete Monitor Timings standard 237 * - ``V4L2_DV_BT_STD_CVT`` 238 - The timings follow the VESA Coordinated Video Timings standard 239 * - ``V4L2_DV_BT_STD_GTF`` 240 - The timings follow the VESA Generalized Timings Formula standard 241 * - ``V4L2_DV_BT_STD_SDI`` 242 - The timings follow the SDI Timings standard. 243 There are no horizontal syncs/porches at all in this format. 244 Total blanking timings must be set in hsync or vsync fields only. 245 246.. tabularcolumns:: |p{7.0cm}|p{10.5cm}| 247 248.. _dv-bt-flags: 249 250.. flat-table:: DV BT Timing flags 251 :header-rows: 0 252 :stub-columns: 0 253 254 * - Flag 255 - Description 256 * - ``V4L2_DV_FL_REDUCED_BLANKING`` 257 - CVT/GTF specific: the timings use reduced blanking (CVT) or the 258 'Secondary GTF' curve (GTF). In both cases the horizontal and/or 259 vertical blanking intervals are reduced, allowing a higher 260 resolution over the same bandwidth. This is a read-only flag, 261 applications must not set this. 262 * - ``V4L2_DV_FL_CAN_REDUCE_FPS`` 263 - CEA-861 specific: set for CEA-861 formats with a framerate that is 264 a multiple of six. These formats can be optionally played at 1 / 265 1.001 speed to be compatible with 60 Hz based standards such as 266 NTSC and PAL-M that use a framerate of 29.97 frames per second. If 267 the transmitter can't generate such frequencies, then the flag 268 will also be cleared. This is a read-only flag, applications must 269 not set this. 270 * - ``V4L2_DV_FL_REDUCED_FPS`` 271 - CEA-861 specific: only valid for video transmitters or video 272 receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS`` 273 set. This flag is cleared otherwise. It is also only valid for 274 formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other 275 formats the flag will be cleared by the driver. 276 277 If the application sets this flag for a transmitter, then the 278 pixelclock used to set up the transmitter is divided by 1.001 to 279 make it compatible with NTSC framerates. If the transmitter can't 280 generate such frequencies, then the flag will be cleared. 281 282 If a video receiver detects that the format uses a reduced framerate, 283 then it will set this flag to signal this to the application. 284 * - ``V4L2_DV_FL_HALF_LINE`` 285 - Specific to interlaced formats: if set, then the vertical 286 frontporch of field 1 (aka the odd field) is really one half-line 287 longer and the vertical backporch of field 2 (aka the even field) 288 is really one half-line shorter, so each field has exactly the 289 same number of half-lines. Whether half-lines can be detected or 290 used depends on the hardware. 291 * - ``V4L2_DV_FL_IS_CE_VIDEO`` 292 - If set, then this is a Consumer Electronics (CE) video format. 293 Such formats differ from other formats (commonly called IT 294 formats) in that if R'G'B' encoding is used then by default the 295 R'G'B' values use limited range (i.e. 16-235) as opposed to full 296 range (i.e. 0-255). All formats defined in CEA-861 except for the 297 640x480p59.94 format are CE formats. 298 * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE`` 299 - Some formats like SMPTE-125M have an interlaced signal with a odd 300 total height. For these formats, if this flag is set, the first 301 field has the extra line. Else, it is the second field. 302 * - ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` 303 - If set, then the picture_aspect field is valid. Otherwise assume that 304 the pixels are square, so the picture aspect ratio is the same as the 305 width to height ratio. 306 * - ``V4L2_DV_FL_HAS_CEA861_VIC`` 307 - If set, then the cea861_vic field is valid and contains the Video 308 Identification Code as per the CEA-861 standard. 309 * - ``V4L2_DV_FL_HAS_HDMI_VIC`` 310 - If set, then the hdmi_vic field is valid and contains the Video 311 Identification Code as per the HDMI standard (HDMI Vendor Specific 312 InfoFrame). 313 * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS`` 314 - CEA-861 specific: only valid for video receivers, the flag is 315 cleared by transmitters. 316 If set, then the hardware can detect the difference between 317 regular framerates and framerates reduced by 1000/1001. E.g.: 318 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz. 319