blob: 8b268354d44270cc9b419ca0164bcf8a7f68512c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
|
.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_ENUM_FRAMESIZES:
****************************
ioctl VIDIOC_ENUM_FRAMESIZES
****************************
Name
====
VIDIOC_ENUM_FRAMESIZES - Enumerate frame sizes
Synopsis
========
.. cpp:function:: int ioctl( int fd, int request, struct v4l2_frmsizeenum *argp )
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``request``
VIDIOC_ENUM_FRAMESIZES
``argp``
Pointer to a struct :ref:`v4l2_frmsizeenum <v4l2-frmsizeenum>`
that contains an index and pixel format and receives a frame width
and height.
Description
===========
This ioctl allows applications to enumerate all frame sizes (i. e. width
and height in pixels) that the device supports for the given pixel
format.
The supported pixel formats can be obtained by using the
:ref:`VIDIOC_ENUM_FMT` function.
The return value and the content of the ``v4l2_frmsizeenum.type`` field
depend on the type of frame sizes the device supports. Here are the
semantics of the function for the different cases:
- **Discrete:** The function returns success if the given index value
(zero-based) is valid. The application should increase the index by
one for each call until ``EINVAL`` is returned. The
``v4l2_frmsizeenum.type`` field is set to
``V4L2_FRMSIZE_TYPE_DISCRETE`` by the driver. Of the union only the
``discrete`` member is valid.
- **Step-wise:** The function returns success if the given index value
is zero and ``EINVAL`` for any other index value. The
``v4l2_frmsizeenum.type`` field is set to
``V4L2_FRMSIZE_TYPE_STEPWISE`` by the driver. Of the union only the
``stepwise`` member is valid.
- **Continuous:** This is a special case of the step-wise type above.
The function returns success if the given index value is zero and
``EINVAL`` for any other index value. The ``v4l2_frmsizeenum.type``
field is set to ``V4L2_FRMSIZE_TYPE_CONTINUOUS`` by the driver. Of
the union only the ``stepwise`` member is valid and the
``step_width`` and ``step_height`` values are set to 1.
When the application calls the function with index zero, it must check
the ``type`` field to determine the type of frame size enumeration the
device supports. Only for the ``V4L2_FRMSIZE_TYPE_DISCRETE`` type does
it make sense to increase the index value to receive more frame sizes.
.. note:: The order in which the frame sizes are returned has no special
meaning. In particular does it not say anything about potential default
format sizes.
Applications can assume that the enumeration data does not change
without any interaction from the application itself. This means that the
enumeration data is consistent if the application does not perform any
other ioctl calls while it runs the frame size enumeration.
Structs
=======
In the structs below, *IN* denotes a value that has to be filled in by
the application, *OUT* denotes values that the driver fills in. The
application should zero out all members except for the *IN* fields.
.. _v4l2-frmsize-discrete:
.. flat-table:: struct v4l2_frmsize_discrete
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- __u32
- ``width``
- Width of the frame [pixel].
- .. row 2
- __u32
- ``height``
- Height of the frame [pixel].
.. _v4l2-frmsize-stepwise:
.. flat-table:: struct v4l2_frmsize_stepwise
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- __u32
- ``min_width``
- Minimum frame width [pixel].
- .. row 2
- __u32
- ``max_width``
- Maximum frame width [pixel].
- .. row 3
- __u32
- ``step_width``
- Frame width step size [pixel].
- .. row 4
- __u32
- ``min_height``
- Minimum frame height [pixel].
- .. row 5
- __u32
- ``max_height``
- Maximum frame height [pixel].
- .. row 6
- __u32
- ``step_height``
- Frame height step size [pixel].
.. _v4l2-frmsizeenum:
.. flat-table:: struct v4l2_frmsizeenum
:header-rows: 0
:stub-columns: 0
- .. row 1
- __u32
- ``index``
-
- IN: Index of the given frame size in the enumeration.
- .. row 2
- __u32
- ``pixel_format``
-
- IN: Pixel format for which the frame sizes are enumerated.
- .. row 3
- __u32
- ``type``
-
- OUT: Frame size type the device supports.
- .. row 4
- union
-
-
- OUT: Frame size with the given index.
- .. row 5
-
- struct :ref:`v4l2_frmsize_discrete <v4l2-frmsize-discrete>`
- ``discrete``
-
- .. row 6
-
- struct :ref:`v4l2_frmsize_stepwise <v4l2-frmsize-stepwise>`
- ``stepwise``
-
- .. row 7
- __u32
- ``reserved[2]``
-
- Reserved space for future use. Must be zeroed by drivers and
applications.
Enums
=====
.. _v4l2-frmsizetypes:
.. flat-table:: enum v4l2_frmsizetypes
:header-rows: 0
:stub-columns: 0
:widths: 3 1 4
- .. row 1
- ``V4L2_FRMSIZE_TYPE_DISCRETE``
- 1
- Discrete frame size.
- .. row 2
- ``V4L2_FRMSIZE_TYPE_CONTINUOUS``
- 2
- Continuous frame size.
- .. row 3
- ``V4L2_FRMSIZE_TYPE_STEPWISE``
- 3
- Step-wise defined frame size.
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.
|
