diff options
Diffstat (limited to 'Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst | 317 |
1 files changed, 317 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst b/Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst new file mode 100644 index 0000000000..6518d857c1 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-g-dv-timings.rst @@ -0,0 +1,317 @@ +.. 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. |