vidioc-subdev-enum-frame-interval.rst (3574B)
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL: 5 6*************************************** 7ioctl VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL 8*************************************** 9 10Name 11==== 12 13VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL - Enumerate frame intervals 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL 19 20``int ioctl(int fd, VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL, struct v4l2_subdev_frame_interval_enum * argp)`` 21 22Arguments 23========= 24 25``fd`` 26 File descriptor returned by :c:func:`open()`. 27 28``argp`` 29 Pointer to struct :c:type:`v4l2_subdev_frame_interval_enum`. 30 31Description 32=========== 33 34This ioctl lets applications enumerate available frame intervals on a 35given sub-device pad. Frame intervals only makes sense for sub-devices 36that can control the frame period on their own. This includes, for 37instance, image sensors and TV tuners. 38 39For the common use case of image sensors, the frame intervals available 40on the sub-device output pad depend on the frame format and size on the 41same pad. Applications must thus specify the desired format and size 42when enumerating frame intervals. 43 44To enumerate frame intervals applications initialize the ``index``, 45``pad``, ``which``, ``code``, ``width`` and ``height`` fields of struct 46:c:type:`v4l2_subdev_frame_interval_enum` 47and call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL` ioctl with a pointer 48to this structure. Drivers fill the rest of the structure or return an 49EINVAL error code if one of the input fields is invalid. All frame 50intervals are enumerable by beginning at index zero and incrementing by 51one until ``EINVAL`` is returned. 52 53Available frame intervals may depend on the current 'try' formats at 54other pads of the sub-device, as well as on the current active links. 55See :ref:`VIDIOC_SUBDEV_G_FMT` for more 56information about the try formats. 57 58Sub-devices that support the frame interval enumeration ioctl should 59implemented it on a single pad only. Its behaviour when supported on 60multiple pads of the same sub-device is not defined. 61 62.. c:type:: v4l2_subdev_frame_interval_enum 63 64.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| 65 66.. flat-table:: struct v4l2_subdev_frame_interval_enum 67 :header-rows: 0 68 :stub-columns: 0 69 :widths: 1 1 2 70 71 * - __u32 72 - ``index`` 73 - Number of the format in the enumeration, set by the application. 74 * - __u32 75 - ``pad`` 76 - Pad number as reported by the media controller API. 77 * - __u32 78 - ``code`` 79 - The media bus format code, as defined in 80 :ref:`v4l2-mbus-format`. 81 * - __u32 82 - ``width`` 83 - Frame width, in pixels. 84 * - __u32 85 - ``height`` 86 - Frame height, in pixels. 87 * - struct :c:type:`v4l2_fract` 88 - ``interval`` 89 - Period, in seconds, between consecutive video frames. 90 * - __u32 91 - ``which`` 92 - Frame intervals to be enumerated, from enum 93 :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. 94 * - __u32 95 - ``reserved``\ [8] 96 - Reserved for future extensions. Applications and drivers must set 97 the array to zero. 98 99Return Value 100============ 101 102On success 0 is returned, on error -1 and the ``errno`` variable is set 103appropriately. The generic error codes are described at the 104:ref:`Generic Error Codes <gen-errors>` chapter. 105 106EINVAL 107 The struct 108 :c:type:`v4l2_subdev_frame_interval_enum` 109 ``pad`` references a non-existing pad, one of the ``code``, 110 ``width`` or ``height`` fields are invalid for the given pad or the 111 ``index`` field is out of bounds.