media/v4l/vidioc-enum-frameintervals.rst

1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
13 VIDIOC_ENUM_FRAMEINTERVALS - Enumerate frame intervals
30     that contains a pixel format and size and receives a frame interval.
35 This ioctl allows applications to enumerate all frame intervals that the
36 device supports for the given pixel format and frame size.
38 The supported pixel formats and frame sizes can be obtained by using the
43 depend on the type of frame intervals the device supports. Here are the
46 -  **Discrete:** The function returns success if the given index value
47    (zero-based) is valid. The application should increase the index by
53 -  **Step-wise:** The function returns success if the given index value
59 -  **Continuous:** This is a special case of the step-wise type above.
67 the ``type`` field to determine the type of frame interval enumeration
69 does it make sense to increase the index value to receive more frame
74    The order in which the frame intervals are returned has no
76    default frame intervals.
81 other ioctl calls while it runs the frame interval enumeration.
85    **Frame intervals and frame rates:** The V4L2 API uses frame
86    intervals instead of frame rates. Given the frame interval the frame
102 .. flat-table:: struct v4l2_frmival_stepwise
103     :header-rows:  0
104     :stub-columns: 0
107     * - struct :c:type:`v4l2_fract`
108       - ``min``
109       - Minimum frame interval [s].
110     * - struct :c:type:`v4l2_fract`
111       - ``max``
112       - Maximum frame interval [s].
113     * - struct :c:type:`v4l2_fract`
114       - ``step``
115       - Frame interval step size [s].
122 .. flat-table:: struct v4l2_frmivalenum
123     :header-rows:  0
124     :stub-columns: 0
126     * - __u32
127       - ``index``
128       - IN: Index of the given frame interval in the enumeration.
129     * - __u32
130       - ``pixel_format``
131       - IN: Pixel format for which the frame intervals are enumerated.
132     * - __u32
133       - ``width``
134       - IN: Frame width for which the frame intervals are enumerated.
135     * - __u32
136       - ``height``
137       - IN: Frame height for which the frame intervals are enumerated.
138     * - __u32
139       - ``type``
140       - OUT: Frame interval type the device supports.
141     * - union {
142       - (anonymous)
143       - OUT: Frame interval with the given index.
144     * - struct :c:type:`v4l2_fract`
145       - ``discrete``
146       - Frame interval [s].
147     * - struct :c:type:`v4l2_frmival_stepwise`
148       - ``stepwise``
149       -
150     * - }
151       -
152       -
153     * - __u32
154       - ``reserved[2]``
155       - Reserved space for future use. Must be zeroed by drivers and
166 .. flat-table:: enum v4l2_frmivaltypes
167     :header-rows:  0
168     :stub-columns: 0
171     * - ``V4L2_FRMIVAL_TYPE_DISCRETE``
172       - 1
173       - Discrete frame interval.
174     * - ``V4L2_FRMIVAL_TYPE_CONTINUOUS``
175       - 2
176       - Continuous frame interval.
177     * - ``V4L2_FRMIVAL_TYPE_STEPWISE``
178       - 3
179       - Step-wise defined frame interval.
184 On success 0 is returned, on error -1 and the ``errno`` variable is set
186 :ref:`Generic Error Codes <gen-errors>` chapter.