1 .. SPDX-License-Identifier: GFDL-1.1-no-invari 1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2 .. c:namespace:: V4L 2 .. c:namespace:: V4L
3 3
4 .. _VIDIOC_G_JPEGCOMP: 4 .. _VIDIOC_G_JPEGCOMP:
5 5
6 ****************************************** 6 ******************************************
7 ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP 7 ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP
8 ****************************************** 8 ******************************************
9 9
10 Name 10 Name
11 ==== 11 ====
12 12
13 VIDIOC_G_JPEGCOMP - VIDIOC_S_JPEGCOMP 13 VIDIOC_G_JPEGCOMP - VIDIOC_S_JPEGCOMP
14 14
15 Synopsis 15 Synopsis
16 ======== 16 ========
17 17
18 .. c:macro:: VIDIOC_G_JPEGCOMP 18 .. c:macro:: VIDIOC_G_JPEGCOMP
19 19
20 ``int ioctl(int fd, VIDIOC_G_JPEGCOMP, v4l2_jp 20 ``int ioctl(int fd, VIDIOC_G_JPEGCOMP, v4l2_jpegcompression *argp)``
21 21
22 .. c:macro:: VIDIOC_S_JPEGCOMP 22 .. c:macro:: VIDIOC_S_JPEGCOMP
23 23
24 ``int ioctl(int fd, VIDIOC_S_JPEGCOMP, const v 24 ``int ioctl(int fd, VIDIOC_S_JPEGCOMP, const v4l2_jpegcompression *argp)``
25 25
26 Arguments 26 Arguments
27 ========= 27 =========
28 28
29 ``fd`` 29 ``fd``
30 File descriptor returned by :c:func:`open( 30 File descriptor returned by :c:func:`open()`.
31 31
32 ``argp`` 32 ``argp``
33 Pointer to struct :c:type:`v4l2_jpegcompre 33 Pointer to struct :c:type:`v4l2_jpegcompression`.
34 34
35 Description 35 Description
36 =========== 36 ===========
37 37
38 These ioctls are **deprecated**. New drivers a 38 These ioctls are **deprecated**. New drivers and applications should use
39 :ref:`JPEG class controls <jpeg-controls>` for 39 :ref:`JPEG class controls <jpeg-controls>` for image quality and JPEG
40 markers control. 40 markers control.
41 41
42 [to do] 42 [to do]
43 43
44 Ronald Bultje elaborates: 44 Ronald Bultje elaborates:
45 45
46 APP is some application-specific information. 46 APP is some application-specific information. The application can set it
47 itself, and it'll be stored in the JPEG-encode 47 itself, and it'll be stored in the JPEG-encoded fields (eg; interlacing
48 information for in an AVI or so). COM is the s 48 information for in an AVI or so). COM is the same, but it's comments,
49 like 'encoded by me' or so. 49 like 'encoded by me' or so.
50 50
51 jpeg_markers describes whether the huffman tab 51 jpeg_markers describes whether the huffman tables, quantization tables
52 and the restart interval information (all JPEG 52 and the restart interval information (all JPEG-specific stuff) should be
53 stored in the JPEG-encoded fields. These defin 53 stored in the JPEG-encoded fields. These define how the JPEG field is
54 encoded. If you omit them, applications assume 54 encoded. If you omit them, applications assume you've used standard
55 encoding. You usually do want to add them. 55 encoding. You usually do want to add them.
56 56
57 .. tabularcolumns:: |p{1.2cm}|p{3.0cm}|p{13.1c 57 .. tabularcolumns:: |p{1.2cm}|p{3.0cm}|p{13.1cm}|
58 58
59 .. c:type:: v4l2_jpegcompression 59 .. c:type:: v4l2_jpegcompression
60 60
61 .. flat-table:: struct v4l2_jpegcompression 61 .. flat-table:: struct v4l2_jpegcompression
62 :header-rows: 0 62 :header-rows: 0
63 :stub-columns: 0 63 :stub-columns: 0
64 :widths: 1 1 2 64 :widths: 1 1 2
65 65
66 * - int 66 * - int
67 - ``quality`` 67 - ``quality``
68 - Deprecated. If 68 - Deprecated. If
69 :ref:`V4L2_CID_JPEG_COMPRESSION_QUALIT 69 :ref:`V4L2_CID_JPEG_COMPRESSION_QUALITY <jpeg-quality-control>`
70 control is exposed by a driver applica 70 control is exposed by a driver applications should use it instead
71 and ignore this field. 71 and ignore this field.
72 * - int 72 * - int
73 - ``APPn`` 73 - ``APPn``
74 - 74 -
75 * - int 75 * - int
76 - ``APP_len`` 76 - ``APP_len``
77 - 77 -
78 * - char 78 * - char
79 - ``APP_data``\ [60] 79 - ``APP_data``\ [60]
80 - 80 -
81 * - int 81 * - int
82 - ``COM_len`` 82 - ``COM_len``
83 - 83 -
84 * - char 84 * - char
85 - ``COM_data``\ [60] 85 - ``COM_data``\ [60]
86 - 86 -
87 * - __u32 87 * - __u32
88 - ``jpeg_markers`` 88 - ``jpeg_markers``
89 - See :ref:`jpeg-markers`. Deprecated. I 89 - See :ref:`jpeg-markers`. Deprecated. If
90 :ref:`V4L2_CID_JPEG_ACTIVE_MARKER <jpe 90 :ref:`V4L2_CID_JPEG_ACTIVE_MARKER <jpeg-active-marker-control>`
91 control is exposed by a driver applica 91 control is exposed by a driver applications should use it instead
92 and ignore this field. 92 and ignore this field.
93 93
94 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm 94 .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|
95 95
96 .. _jpeg-markers: 96 .. _jpeg-markers:
97 97
98 .. flat-table:: JPEG Markers Flags 98 .. flat-table:: JPEG Markers Flags
99 :header-rows: 0 99 :header-rows: 0
100 :stub-columns: 0 100 :stub-columns: 0
101 :widths: 3 1 4 101 :widths: 3 1 4
102 102
103 * - ``V4L2_JPEG_MARKER_DHT`` 103 * - ``V4L2_JPEG_MARKER_DHT``
104 - (1<<3) 104 - (1<<3)
105 - Define Huffman Tables 105 - Define Huffman Tables
106 * - ``V4L2_JPEG_MARKER_DQT`` 106 * - ``V4L2_JPEG_MARKER_DQT``
107 - (1<<4) 107 - (1<<4)
108 - Define Quantization Tables 108 - Define Quantization Tables
109 * - ``V4L2_JPEG_MARKER_DRI`` 109 * - ``V4L2_JPEG_MARKER_DRI``
110 - (1<<5) 110 - (1<<5)
111 - Define Restart Interval 111 - Define Restart Interval
112 * - ``V4L2_JPEG_MARKER_COM`` 112 * - ``V4L2_JPEG_MARKER_COM``
113 - (1<<6) 113 - (1<<6)
114 - Comment segment 114 - Comment segment
115 * - ``V4L2_JPEG_MARKER_APP`` 115 * - ``V4L2_JPEG_MARKER_APP``
116 - (1<<7) 116 - (1<<7)
117 - App segment, driver will always use AP 117 - App segment, driver will always use APP0
118 118
119 Return Value 119 Return Value
120 ============ 120 ============
121 121
122 On success 0 is returned, on error -1 and the 122 On success 0 is returned, on error -1 and the ``errno`` variable is set
123 appropriately. The generic error codes are des 123 appropriately. The generic error codes are described at the
124 :ref:`Generic Error Codes <gen-errors>` chapte 124 :ref:`Generic Error Codes <gen-errors>` chapter.
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