projects / deliverable / linux.git / blame
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1 | .. -*- coding: utf-8; mode: rst -*- |
| 2 | ||
| af4a4d0d | 3 | .. _VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL: |
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4 | |
| 5 | *************************************** | |
| 6 | ioctl VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL | |
| 7 | *************************************** | |
| 8 | ||
| 9 | *man VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL(2)* | |
| 10 | ||
| 11 | Enumerate frame intervals | |
| 12 | ||
| 13 | ||
| 14 | Synopsis | |
| 15 | ======== | |
| 16 | ||
| 17 | .. c:function:: int ioctl( int fd, int request, struct v4l2_subdev_frame_interval_enum * argp ) | |
| 18 | ||
| 19 | Arguments | |
| 20 | ========= | |
| 21 | ||
| 22 | ``fd`` | |
| 23 | File descriptor returned by :ref:`open() <func-open>`. | |
| 24 | ||
| 25 | ``request`` | |
| 26 | VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL | |
| 27 | ||
| 28 | ``argp`` | |
| 29 | ||
| 30 | ||
| 31 | Description | |
| 32 | =========== | |
| 33 | ||
| 34 | This ioctl lets applications enumerate available frame intervals on a | |
| 35 | given sub-device pad. Frame intervals only makes sense for sub-devices | |
| 36 | that can control the frame period on their own. This includes, for | |
| 37 | instance, image sensors and TV tuners. | |
| 38 | ||
| 39 | For the common use case of image sensors, the frame intervals available | |
| 40 | on the sub-device output pad depend on the frame format and size on the | |
| 41 | same pad. Applications must thus specify the desired format and size | |
| 42 | when enumerating frame intervals. | |
| 43 | ||
| 44 | To enumerate frame intervals applications initialize the ``index``, | |
| 45 | ``pad``, ``which``, ``code``, ``width`` and ``height`` fields of struct | |
| 46 | :ref:`v4l2_subdev_frame_interval_enum <v4l2-subdev-frame-interval-enum>` | |
| 2212ff25 | 47 | and call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL` ioctl with a pointer |
| 5377d91f MH |
48 | to this structure. Drivers fill the rest of the structure or return an |
| 49 | EINVAL error code if one of the input fields is invalid. All frame | |
| 50 | intervals are enumerable by beginning at index zero and incrementing by | |
| 51 | one until EINVAL is returned. | |
| 52 | ||
| 53 | Available frame intervals may depend on the current 'try' formats at | |
| 54 | other pads of the sub-device, as well as on the current active links. | |
| 7347081e | 55 | See :ref:`VIDIOC_SUBDEV_G_FMT` for more |
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56 | information about the try formats. |
| 57 | ||
| 58 | Sub-devices that support the frame interval enumeration ioctl should | |
| 59 | implemented it on a single pad only. Its behaviour when supported on | |
| 60 | multiple pads of the same sub-device is not defined. | |
| 61 | ||
| 62 | ||
| 63 | .. _v4l2-subdev-frame-interval-enum: | |
| 64 | ||
| 65 | .. flat-table:: struct v4l2_subdev_frame_interval_enum | |
| 66 | :header-rows: 0 | |
| 67 | :stub-columns: 0 | |
| 68 | :widths: 1 1 2 | |
| 69 | ||
| 70 | ||
| 71 | - .. row 1 | |
| 72 | ||
| 73 | - __u32 | |
| 74 | ||
| 75 | - ``index`` | |
| 76 | ||
| 77 | - Number of the format in the enumeration, set by the application. | |
| 78 | ||
| 79 | - .. row 2 | |
| 80 | ||
| 81 | - __u32 | |
| 82 | ||
| 83 | - ``pad`` | |
| 84 | ||
| 85 | - Pad number as reported by the media controller API. | |
| 86 | ||
| 87 | - .. row 3 | |
| 88 | ||
| 89 | - __u32 | |
| 90 | ||
| 91 | - ``code`` | |
| 92 | ||
| 93 | - The media bus format code, as defined in | |
| 94 | :ref:`v4l2-mbus-format`. | |
| 95 | ||
| 96 | - .. row 4 | |
| 97 | ||
| 98 | - __u32 | |
| 99 | ||
| 100 | - ``width`` | |
| 101 | ||
| 102 | - Frame width, in pixels. | |
| 103 | ||
| 104 | - .. row 5 | |
| 105 | ||
| 106 | - __u32 | |
| 107 | ||
| 108 | - ``height`` | |
| 109 | ||
| 110 | - Frame height, in pixels. | |
| 111 | ||
| 112 | - .. row 6 | |
| 113 | ||
| 114 | - struct :ref:`v4l2_fract <v4l2-fract>` | |
| 115 | ||
| 116 | - ``interval`` | |
| 117 | ||
| 118 | - Period, in seconds, between consecutive video frames. | |
| 119 | ||
| 120 | - .. row 7 | |
| 121 | ||
| 122 | - __u32 | |
| 123 | ||
| 124 | - ``which`` | |
| 125 | ||
| 126 | - Frame intervals to be enumerated, from enum | |
| 127 | :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. | |
| 128 | ||
| 129 | - .. row 8 | |
| 130 | ||
| 131 | - __u32 | |
| 132 | ||
| 133 | - ``reserved``\ [8] | |
| 134 | ||
| 135 | - Reserved for future extensions. Applications and drivers must set | |
| 136 | the array to zero. | |
| 137 | ||
| 138 | ||
| 139 | ||
| 140 | Return Value | |
| 141 | ============ | |
| 142 | ||
| 143 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
| 144 | appropriately. The generic error codes are described at the | |
| 145 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
| 146 | ||
| 147 | EINVAL | |
| 148 | The struct | |
| 149 | :ref:`v4l2_subdev_frame_interval_enum <v4l2-subdev-frame-interval-enum>` | |
| 150 | ``pad`` references a non-existing pad, one of the ``code``, | |
| 151 | ``width`` or ``height`` fields are invalid for the given pad or the | |
| 152 | ``index`` field is out of bounds. | |
| 153 | ||
| 154 | ||
| 155 | .. ------------------------------------------------------------------------------ | |
| 156 | .. This file was automatically converted from DocBook-XML with the dbxml | |
| 157 | .. library (https://github.com/return42/sphkerneldoc). The origin XML comes | |
| 158 | .. from the linux kernel, refer to: | |
| 159 | .. | |
| 160 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook | |
| 161 | .. ------------------------------------------------------------------------------ |