| .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later |
| .. c:namespace:: V4L |
| |
| .. _VIDIOC_G_DV_TIMINGS: |
| |
| ********************************************** |
| ioctl VIDIOC_G_DV_TIMINGS, VIDIOC_S_DV_TIMINGS |
| ********************************************** |
| |
| Name |
| ==== |
| |
| 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 |
| |
| Synopsis |
| ======== |
| |
| .. c:macro:: VIDIOC_G_DV_TIMINGS |
| |
| ``int ioctl(int fd, VIDIOC_G_DV_TIMINGS, struct v4l2_dv_timings *argp)`` |
| |
| .. c:macro:: VIDIOC_S_DV_TIMINGS |
| |
| ``int ioctl(int fd, VIDIOC_S_DV_TIMINGS, struct v4l2_dv_timings *argp)`` |
| |
| .. c:macro:: VIDIOC_SUBDEV_G_DV_TIMINGS |
| |
| ``int ioctl(int fd, VIDIOC_SUBDEV_G_DV_TIMINGS, struct v4l2_dv_timings *argp)`` |
| |
| .. c:macro:: VIDIOC_SUBDEV_S_DV_TIMINGS |
| |
| ``int ioctl(int fd, VIDIOC_SUBDEV_S_DV_TIMINGS, struct v4l2_dv_timings *argp)`` |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :c:func:`open()`. |
| |
| ``argp`` |
| Pointer to struct :c:type:`v4l2_dv_timings`. |
| |
| Description |
| =========== |
| |
| To set DV timings for the input or output, applications use the |
| :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl and to get the current timings, |
| applications use the :ref:`VIDIOC_G_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` ioctl. The detailed timing |
| information is filled in using the structure struct |
| :c:type:`v4l2_dv_timings`. These ioctls take a |
| pointer to the struct :c:type:`v4l2_dv_timings` |
| structure as argument. If the ioctl is not supported or the timing |
| values are not correct, the driver returns ``EINVAL`` error code. |
| |
| Calling ``VIDIOC_SUBDEV_S_DV_TIMINGS`` on a subdev device node that has been |
| registered in read-only mode is not allowed. An error is returned and the errno |
| variable is set to ``-EPERM``. |
| |
| The ``linux/v4l2-dv-timings.h`` header can be used to get the timings of |
| the formats in the :ref:`cea861` and :ref:`vesadmt` standards. If |
| the current input or output does not support DV timings (e.g. if |
| :ref:`VIDIOC_ENUMINPUT` does not set the |
| ``V4L2_IN_CAP_DV_TIMINGS`` flag), then ``ENODATA`` error code is returned. |
| |
| Return Value |
| ============ |
| |
| On success 0 is returned, on error -1 and the ``errno`` variable is set |
| appropriately. The generic error codes are described at the |
| :ref:`Generic Error Codes <gen-errors>` chapter. |
| |
| EINVAL |
| This ioctl is not supported, or the :ref:`VIDIOC_S_DV_TIMINGS <VIDIOC_G_DV_TIMINGS>` |
| parameter was unsuitable. |
| |
| ENODATA |
| Digital video timings are not supported for this input or output. |
| |
| EBUSY |
| The device is busy and therefore can not change the timings. |
| |
| EPERM |
| ``VIDIOC_SUBDEV_S_DV_TIMINGS`` has been called on a read-only subdevice. |
| |
| .. c:type:: v4l2_bt_timings |
| |
| .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| |
| |
| .. cssclass:: longtable |
| |
| .. flat-table:: struct v4l2_bt_timings |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 1 2 |
| |
| * - __u32 |
| - ``width`` |
| - Width of the active video in pixels. |
| * - __u32 |
| - ``height`` |
| - Height of the active video frame in lines. So for interlaced |
| formats the height of the active video in each field is |
| ``height``/2. |
| * - __u32 |
| - ``interlaced`` |
| - Progressive (``V4L2_DV_PROGRESSIVE``) or interlaced (``V4L2_DV_INTERLACED``). |
| * - __u32 |
| - ``polarities`` |
| - This is a bit mask that defines polarities of sync signals. bit 0 |
| (``V4L2_DV_VSYNC_POS_POL``) is for vertical sync polarity and bit |
| 1 (``V4L2_DV_HSYNC_POS_POL``) is for horizontal sync polarity. If |
| the bit is set (1) it is positive polarity and if is cleared (0), |
| it is negative polarity. |
| * - __u64 |
| - ``pixelclock`` |
| - Pixel clock in Hz. Ex. 74.25MHz->74250000 |
| * - __u32 |
| - ``hfrontporch`` |
| - Horizontal front porch in pixels |
| * - __u32 |
| - ``hsync`` |
| - Horizontal sync length in pixels |
| * - __u32 |
| - ``hbackporch`` |
| - Horizontal back porch in pixels |
| * - __u32 |
| - ``vfrontporch`` |
| - Vertical front porch in lines. For interlaced formats this refers |
| to the odd field (aka field 1). |
| * - __u32 |
| - ``vsync`` |
| - Vertical sync length in lines. For interlaced formats this refers |
| to the odd field (aka field 1). |
| * - __u32 |
| - ``vbackporch`` |
| - Vertical back porch in lines. For interlaced formats this refers |
| to the odd field (aka field 1). |
| * - __u32 |
| - ``il_vfrontporch`` |
| - Vertical front porch in lines for the even field (aka field 2) of |
| interlaced field formats. Must be 0 for progressive formats. |
| * - __u32 |
| - ``il_vsync`` |
| - Vertical sync length in lines for the even field (aka field 2) of |
| interlaced field formats. Must be 0 for progressive formats. |
| * - __u32 |
| - ``il_vbackporch`` |
| - Vertical back porch in lines for the even field (aka field 2) of |
| interlaced field formats. Must be 0 for progressive formats. |
| * - __u32 |
| - ``standards`` |
| - The video standard(s) this format belongs to. This will be filled |
| in by the driver. Applications must set this to 0. See |
| :ref:`dv-bt-standards` for a list of standards. |
| * - __u32 |
| - ``flags`` |
| - Several flags giving more information about the format. See |
| :ref:`dv-bt-flags` for a description of the flags. |
| * - struct :c:type:`v4l2_fract` |
| - ``picture_aspect`` |
| - The picture aspect if the pixels are not square. Only valid if the |
| ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` flag is set. |
| * - __u8 |
| - ``cea861_vic`` |
| - The Video Identification Code according to the CEA-861 standard. |
| Only valid if the ``V4L2_DV_FL_HAS_CEA861_VIC`` flag is set. |
| * - __u8 |
| - ``hdmi_vic`` |
| - The Video Identification Code according to the HDMI standard. |
| Only valid if the ``V4L2_DV_FL_HAS_HDMI_VIC`` flag is set. |
| * - __u8 |
| - ``reserved[46]`` |
| - Reserved for future extensions. Drivers and applications must set |
| the array to zero. |
| |
| .. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{7.0cm}|p{3.1cm}| |
| |
| .. c:type:: v4l2_dv_timings |
| |
| .. flat-table:: struct v4l2_dv_timings |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 1 2 |
| |
| * - __u32 |
| - ``type`` |
| - Type of DV timings as listed in :ref:`dv-timing-types`. |
| * - union { |
| - (anonymous) |
| * - struct :c:type:`v4l2_bt_timings` |
| - ``bt`` |
| - Timings defined by BT.656/1120 specifications |
| * - __u32 |
| - ``reserved``\ [32] |
| - |
| * - } |
| - |
| |
| .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| |
| |
| .. _dv-timing-types: |
| |
| .. flat-table:: DV Timing types |
| :header-rows: 0 |
| :stub-columns: 0 |
| :widths: 1 1 2 |
| |
| * - Timing type |
| - value |
| - Description |
| * - |
| - |
| - |
| * - ``V4L2_DV_BT_656_1120`` |
| - 0 |
| - BT.656/1120 timings |
| |
| .. tabularcolumns:: |p{6.5cm}|p{11.0cm}| |
| |
| .. cssclass:: longtable |
| |
| .. _dv-bt-standards: |
| |
| .. flat-table:: DV BT Timing standards |
| :header-rows: 0 |
| :stub-columns: 0 |
| |
| * - Timing standard |
| - Description |
| * - ``V4L2_DV_BT_STD_CEA861`` |
| - The timings follow the CEA-861 Digital TV Profile standard |
| * - ``V4L2_DV_BT_STD_DMT`` |
| - The timings follow the VESA Discrete Monitor Timings standard |
| * - ``V4L2_DV_BT_STD_CVT`` |
| - The timings follow the VESA Coordinated Video Timings standard |
| * - ``V4L2_DV_BT_STD_GTF`` |
| - The timings follow the VESA Generalized Timings Formula standard |
| * - ``V4L2_DV_BT_STD_SDI`` |
| - The timings follow the SDI Timings standard. |
| There are no horizontal syncs/porches at all in this format. |
| Total blanking timings must be set in hsync or vsync fields only. |
| |
| .. tabularcolumns:: |p{7.7cm}|p{9.8cm}| |
| |
| .. cssclass:: longtable |
| |
| .. _dv-bt-flags: |
| |
| .. flat-table:: DV BT Timing flags |
| :header-rows: 0 |
| :stub-columns: 0 |
| |
| * - Flag |
| - Description |
| * - ``V4L2_DV_FL_REDUCED_BLANKING`` |
| - CVT/GTF specific: the timings use reduced blanking (CVT) or the |
| 'Secondary GTF' curve (GTF). In both cases the horizontal and/or |
| vertical blanking intervals are reduced, allowing a higher |
| resolution over the same bandwidth. This is a read-only flag, |
| applications must not set this. |
| * - ``V4L2_DV_FL_CAN_REDUCE_FPS`` |
| - CEA-861 specific: set for CEA-861 formats with a framerate that is |
| a multiple of six. These formats can be optionally played at 1 / |
| 1.001 speed to be compatible with 60 Hz based standards such as |
| NTSC and PAL-M that use a framerate of 29.97 frames per second. If |
| the transmitter can't generate such frequencies, then the flag |
| will also be cleared. This is a read-only flag, applications must |
| not set this. |
| * - ``V4L2_DV_FL_REDUCED_FPS`` |
| - CEA-861 specific: only valid for video transmitters or video |
| receivers that have the ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS`` |
| set. This flag is cleared otherwise. It is also only valid for |
| formats with the ``V4L2_DV_FL_CAN_REDUCE_FPS`` flag set, for other |
| formats the flag will be cleared by the driver. |
| |
| If the application sets this flag for a transmitter, then the |
| pixelclock used to set up the transmitter is divided by 1.001 to |
| make it compatible with NTSC framerates. If the transmitter can't |
| generate such frequencies, then the flag will be cleared. |
| |
| If a video receiver detects that the format uses a reduced framerate, |
| then it will set this flag to signal this to the application. |
| * - ``V4L2_DV_FL_HALF_LINE`` |
| - Specific to interlaced formats: if set, then the vertical |
| frontporch of field 1 (aka the odd field) is really one half-line |
| longer and the vertical backporch of field 2 (aka the even field) |
| is really one half-line shorter, so each field has exactly the |
| same number of half-lines. Whether half-lines can be detected or |
| used depends on the hardware. |
| * - ``V4L2_DV_FL_IS_CE_VIDEO`` |
| - If set, then this is a Consumer Electronics (CE) video format. |
| Such formats differ from other formats (commonly called IT |
| formats) in that if R'G'B' encoding is used then by default the |
| R'G'B' values use limited range (i.e. 16-235) as opposed to full |
| range (i.e. 0-255). All formats defined in CEA-861 except for the |
| 640x480p59.94 format are CE formats. |
| * - ``V4L2_DV_FL_FIRST_FIELD_EXTRA_LINE`` |
| - Some formats like SMPTE-125M have an interlaced signal with a odd |
| total height. For these formats, if this flag is set, the first |
| field has the extra line. Else, it is the second field. |
| * - ``V4L2_DV_FL_HAS_PICTURE_ASPECT`` |
| - If set, then the picture_aspect field is valid. Otherwise assume that |
| the pixels are square, so the picture aspect ratio is the same as the |
| width to height ratio. |
| * - ``V4L2_DV_FL_HAS_CEA861_VIC`` |
| - If set, then the cea861_vic field is valid and contains the Video |
| Identification Code as per the CEA-861 standard. |
| * - ``V4L2_DV_FL_HAS_HDMI_VIC`` |
| - If set, then the hdmi_vic field is valid and contains the Video |
| Identification Code as per the HDMI standard (HDMI Vendor Specific |
| InfoFrame). |
| * - ``V4L2_DV_FL_CAN_DETECT_REDUCED_FPS`` |
| - CEA-861 specific: only valid for video receivers, the flag is |
| cleared by transmitters. |
| If set, then the hardware can detect the difference between |
| regular framerates and framerates reduced by 1000/1001. E.g.: |
| 60 vs 59.94 Hz, 30 vs 29.97 Hz or 24 vs 23.976 Hz. |