1 <refentry id=
"vidioc-enum-fmt">
3 <refentrytitle>ioctl VIDIOC_ENUM_FMT
</refentrytitle>
8 <refname>VIDIOC_ENUM_FMT
</refname>
9 <refpurpose>Enumerate image formats
</refpurpose>
15 <funcdef>int
<function>ioctl
</function></funcdef>
16 <paramdef>int
<parameter>fd
</parameter></paramdef>
17 <paramdef>int
<parameter>request
</parameter></paramdef>
18 <paramdef>struct v4l2_fmtdesc
19 *
<parameter>argp
</parameter></paramdef>
25 <title>Arguments
</title>
29 <term><parameter>fd
</parameter></term>
35 <term><parameter>request
</parameter></term>
37 <para>VIDIOC_ENUM_FMT
</para>
41 <term><parameter>argp
</parameter></term>
50 <title>Description
</title>
52 <para>To enumerate image formats applications initialize the
53 <structfield>type
</structfield> and
<structfield>index
</structfield>
54 field of &v4l2-fmtdesc; and call the
55 <constant>VIDIOC_ENUM_FMT
</constant> ioctl with a pointer to this
56 structure. Drivers fill the rest of the structure or return an
57 &EINVAL;. All formats are enumerable by beginning at index zero and
58 incrementing by one until
<errorcode>EINVAL
</errorcode> is
61 <table pgwide=
"1" frame=
"none" id=
"v4l2-fmtdesc">
62 <title>struct
<structname>v4l2_fmtdesc
</structname></title>
68 <entry><structfield>index
</structfield></entry>
69 <entry>Number of the format in the enumeration, set by
70 the application. This is in no way related to the
<structfield>
71 pixelformat
</structfield> field.
</entry>
74 <entry>&v4l2-buf-type;
</entry>
75 <entry><structfield>type
</structfield></entry>
76 <entry>Type of the data stream, set by the application.
77 Only these types are valid here:
78 <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE
</constant>,
79 <constant>V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
</constant>,
80 <constant>V4L2_BUF_TYPE_VIDEO_OUTPUT
</constant>,
81 <constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
</constant>,
82 <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY
</constant>, and custom (driver
83 defined) types with code
<constant>V4L2_BUF_TYPE_PRIVATE
</constant>
88 <entry><structfield>flags
</structfield></entry>
89 <entry>See
<xref linkend=
"fmtdesc-flags" /></entry>
93 <entry><structfield>description
</structfield>[
32]
</entry>
94 <entry>Description of the format, a NUL-terminated ASCII
95 string. This information is intended for the user, for example:
"YUV
100 <entry><structfield>pixelformat
</structfield></entry>
101 <entry>The image format identifier. This is a
102 four character code as computed by the v4l2_fourcc()
106 <entry spanname=
"hspan"><para><programlisting id=
"v4l2-fourcc">
107 #define v4l2_fourcc(a,b,c,d) (((__u32)(a)
<<0)|((__u32)(b)
<<8)|((__u32)(c)
<<16)|((__u32)(d)
<<24))
108 </programlisting></para><para>Several image formats are already
109 defined by this specification in
<xref linkend=
"pixfmt" />. Note these
110 codes are not the same as those used in the Windows world.
</para></entry>
114 <entry><structfield>reserved
</structfield>[
4]
</entry>
115 <entry>Reserved for future extensions. Drivers must set
116 the array to zero.
</entry>
122 <table pgwide=
"1" frame=
"none" id=
"fmtdesc-flags">
123 <title>Image Format Description Flags
</title>
128 <entry><constant>V4L2_FMT_FLAG_COMPRESSED
</constant></entry>
129 <entry>0x0001</entry>
130 <entry>This is a compressed format.
</entry>
133 <entry><constant>V4L2_FMT_FLAG_EMULATED
</constant></entry>
134 <entry>0x0002</entry>
135 <entry>This format is not native to the device but emulated
136 through software (usually libv4l2), where possible try to use a native format
137 instead for better performance.
</entry>
149 <term><errorcode>EINVAL
</errorcode></term>
151 <para>The &v4l2-fmtdesc;
<structfield>type
</structfield>
152 is not supported or the
<structfield>index
</structfield> is out of