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- .. -*- coding: utf-8; mode: rst -*-
- .. _VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL:
- ***************************************
- ioctl VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL
- ***************************************
- Name
- ====
- VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL - Enumerate frame intervals
- Synopsis
- ========
- .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL, struct v4l2_subdev_frame_interval_enum * argp )
- :name: VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL
- Arguments
- =========
- ``fd``
- File descriptor returned by :ref:`open() <func-open>`.
- ``argp``
- Description
- ===========
- This ioctl lets applications enumerate available frame intervals on a
- given sub-device pad. Frame intervals only makes sense for sub-devices
- that can control the frame period on their own. This includes, for
- instance, image sensors and TV tuners.
- For the common use case of image sensors, the frame intervals available
- on the sub-device output pad depend on the frame format and size on the
- same pad. Applications must thus specify the desired format and size
- when enumerating frame intervals.
- To enumerate frame intervals applications initialize the ``index``,
- ``pad``, ``which``, ``code``, ``width`` and ``height`` fields of struct
- :c:type:`v4l2_subdev_frame_interval_enum`
- and call the :ref:`VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL` ioctl with a pointer
- to this structure. Drivers fill the rest of the structure or return an
- EINVAL error code if one of the input fields is invalid. All frame
- intervals are enumerable by beginning at index zero and incrementing by
- one until ``EINVAL`` is returned.
- Available frame intervals may depend on the current 'try' formats at
- other pads of the sub-device, as well as on the current active links.
- See :ref:`VIDIOC_SUBDEV_G_FMT` for more
- information about the try formats.
- Sub-devices that support the frame interval enumeration ioctl should
- implemented it on a single pad only. Its behaviour when supported on
- multiple pads of the same sub-device is not defined.
- .. c:type:: v4l2_subdev_frame_interval_enum
- .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
- .. flat-table:: struct v4l2_subdev_frame_interval_enum
- :header-rows: 0
- :stub-columns: 0
- :widths: 1 1 2
- * - __u32
- - ``index``
- - Number of the format in the enumeration, set by the application.
- * - __u32
- - ``pad``
- - Pad number as reported by the media controller API.
- * - __u32
- - ``code``
- - The media bus format code, as defined in
- :ref:`v4l2-mbus-format`.
- * - __u32
- - ``width``
- - Frame width, in pixels.
- * - __u32
- - ``height``
- - Frame height, in pixels.
- * - struct :c:type:`v4l2_fract`
- - ``interval``
- - Period, in seconds, between consecutive video frames.
- * - __u32
- - ``which``
- - Frame intervals to be enumerated, from enum
- :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
- * - __u32
- - ``reserved``\ [8]
- - Reserved for future extensions. Applications and drivers must set
- the array to zero.
- 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
- The struct
- :c:type:`v4l2_subdev_frame_interval_enum`
- ``pad`` references a non-existing pad, one of the ``code``,
- ``width`` or ``height`` fields are invalid for the given pad or the
- ``index`` field is out of bounds.
|
