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- <title>Image Formats</title>
-
- <para>The V4L2 API was primarily designed for devices exchanging
-image data with applications. The
-<structname>v4l2_pix_format</structname> and <structname>v4l2_pix_format_mplane
-</structname> structures define the format and layout of an image in memory.
-The former is used with the single-planar API, while the latter is used with the
-multi-planar version (see <xref linkend="planar-apis"/>). Image formats are
-negotiated with the &VIDIOC-S-FMT; ioctl. (The explanations here focus on video
-capturing and output, for overlay frame buffer formats see also
-&VIDIOC-G-FBUF;.)</para>
-
-<section>
- <title>Single-planar format structure</title>
- <table pgwide="1" frame="none" id="v4l2-pix-format">
- <title>struct <structname>v4l2_pix_format</structname></title>
- <tgroup cols="3">
- &cs-str;
- <tbody valign="top">
- <row>
- <entry>__u32</entry>
- <entry><structfield>width</structfield></entry>
- <entry>Image width in pixels.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>height</structfield></entry>
- <entry>Image height in pixels.</entry>
- </row>
- <row>
- <entry spanname="hspan">Applications set these fields to
-request an image size, drivers return the closest possible values. In
-case of planar formats the <structfield>width</structfield> and
-<structfield>height</structfield> applies to the largest plane. To
-avoid ambiguities drivers must return values rounded up to a multiple
-of the scale factor of any smaller planes. For example when the image
-format is YUV 4:2:0, <structfield>width</structfield> and
-<structfield>height</structfield> must be multiples of two.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>pixelformat</structfield></entry>
- <entry>The pixel format or type of compression, set by the
-application. This is a little endian <link
-linkend="v4l2-fourcc">four character code</link>. V4L2 defines
-standard RGB formats in <xref linkend="rgb-formats" />, YUV formats in <xref
-linkend="yuv-formats" />, and reserved codes in <xref
-linkend="reserved-formats" /></entry>
- </row>
- <row>
- <entry>&v4l2-field;</entry>
- <entry><structfield>field</structfield></entry>
- <entry>Video images are typically interlaced. Applications
-can request to capture or output only the top or bottom field, or both
-fields interlaced or sequentially stored in one buffer or alternating
-in separate buffers. Drivers return the actual field order selected.
-For details see <xref linkend="field-order" />.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>bytesperline</structfield></entry>
- <entry>Distance in bytes between the leftmost pixels in two
-adjacent lines.</entry>
- </row>
- <row>
- <entry spanname="hspan"><para>Both applications and drivers
-can set this field to request padding bytes at the end of each line.
-Drivers however may ignore the value requested by the application,
-returning <structfield>width</structfield> times bytes per pixel or a
-larger value required by the hardware. That implies applications can
-just set this field to zero to get a reasonable
-default.</para><para>Video hardware may access padding bytes,
-therefore they must reside in accessible memory. Consider cases where
-padding bytes after the last line of an image cross a system page
-boundary. Input devices may write padding bytes, the value is
-undefined. Output devices ignore the contents of padding
-bytes.</para><para>When the image format is planar the
-<structfield>bytesperline</structfield> value applies to the largest
-plane and is divided by the same factor as the
-<structfield>width</structfield> field for any smaller planes. For
-example the Cb and Cr planes of a YUV 4:2:0 image have half as many
-padding bytes following each line as the Y plane. To avoid ambiguities
-drivers must return a <structfield>bytesperline</structfield> value
-rounded up to a multiple of the scale factor.</para></entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>sizeimage</structfield></entry>
- <entry>Size in bytes of the buffer to hold a complete image,
-set by the driver. Usually this is
-<structfield>bytesperline</structfield> times
-<structfield>height</structfield>. When the image consists of variable
-length compressed data this is the maximum number of bytes required to
-hold an image.</entry>
- </row>
- <row>
- <entry>&v4l2-colorspace;</entry>
- <entry><structfield>colorspace</structfield></entry>
- <entry>This information supplements the
-<structfield>pixelformat</structfield> and must be set by the driver,
-see <xref linkend="colorspaces" />.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>priv</structfield></entry>
- <entry>Reserved for custom (driver defined) additional
-information about formats. When not used drivers and applications must
-set this field to zero.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
-</section>
-
-<section>
- <title>Multi-planar format structures</title>
- <para>The <structname>v4l2_plane_pix_format</structname> structures define
- size and layout for each of the planes in a multi-planar format.
- The <structname>v4l2_pix_format_mplane</structname> structure contains
- information common to all planes (such as image width and height) and
- an array of <structname>v4l2_plane_pix_format</structname> structures,
- describing all planes of that format.</para>
- <table pgwide="1" frame="none" id="v4l2-plane-pix-format">
- <title>struct <structname>v4l2_plane_pix_format</structname></title>
- <tgroup cols="3">
- &cs-str;
- <tbody valign="top">
- <row>
- <entry>__u32</entry>
- <entry><structfield>sizeimage</structfield></entry>
- <entry>Maximum size in bytes required for image data in this plane.
- </entry>
- </row>
- <row>
- <entry>__u16</entry>
- <entry><structfield>bytesperline</structfield></entry>
- <entry>Distance in bytes between the leftmost pixels in two adjacent
- lines.</entry>
- </row>
- <row>
- <entry>__u16</entry>
- <entry><structfield>reserved[7]</structfield></entry>
- <entry>Reserved for future extensions. Should be zeroed by the
- application.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- <table pgwide="1" frame="none" id="v4l2-pix-format-mplane">
- <title>struct <structname>v4l2_pix_format_mplane</structname></title>
- <tgroup cols="3">
- &cs-str;
- <tbody valign="top">
- <row>
- <entry>__u32</entry>
- <entry><structfield>width</structfield></entry>
- <entry>Image width in pixels.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>height</structfield></entry>
- <entry>Image height in pixels.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>pixelformat</structfield></entry>
- <entry>The pixel format. Both single- and multi-planar four character
-codes can be used.</entry>
- </row>
- <row>
- <entry>&v4l2-field;</entry>
- <entry><structfield>field</structfield></entry>
- <entry>See &v4l2-pix-format;.</entry>
- </row>
- <row>
- <entry>&v4l2-colorspace;</entry>
- <entry><structfield>colorspace</structfield></entry>
- <entry>See &v4l2-pix-format;.</entry>
- </row>
- <row>
- <entry>&v4l2-plane-pix-format;</entry>
- <entry><structfield>plane_fmt[VIDEO_MAX_PLANES]</structfield></entry>
- <entry>An array of structures describing format of each plane this
- pixel format consists of. The number of valid entries in this array
- has to be put in the <structfield>num_planes</structfield>
- field.</entry>
- </row>
- <row>
- <entry>__u8</entry>
- <entry><structfield>num_planes</structfield></entry>
- <entry>Number of planes (i.e. separate memory buffers) for this format
- and the number of valid entries in the
- <structfield>plane_fmt</structfield> array.</entry>
- </row>
- <row>
- <entry>__u8</entry>
- <entry><structfield>reserved[11]</structfield></entry>
- <entry>Reserved for future extensions. Should be zeroed by the
- application.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
-</section>
-
- <section>
- <title>Standard Image Formats</title>
-
- <para>In order to exchange images between drivers and
-applications, it is necessary to have standard image data formats
-which both sides will interpret the same way. V4L2 includes several
-such formats, and this section is intended to be an unambiguous
-specification of the standard image data formats in V4L2.</para>
-
- <para>V4L2 drivers are not limited to these formats, however.
-Driver-specific formats are possible. In that case the application may
-depend on a codec to convert images to one of the standard formats
-when needed. But the data can still be stored and retrieved in the
-proprietary format. For example, a device may support a proprietary
-compressed format. Applications can still capture and save the data in
-the compressed format, saving much disk space, and later use a codec
-to convert the images to the X Windows screen format when the video is
-to be displayed.</para>
-
- <para>Even so, ultimately, some standard formats are needed, so
-the V4L2 specification would not be complete without well-defined
-standard formats.</para>
-
- <para>The V4L2 standard formats are mainly uncompressed formats. The
-pixels are always arranged in memory from left to right, and from top
-to bottom. The first byte of data in the image buffer is always for
-the leftmost pixel of the topmost row. Following that is the pixel
-immediately to its right, and so on until the end of the top row of
-pixels. Following the rightmost pixel of the row there may be zero or
-more bytes of padding to guarantee that each row of pixel data has a
-certain alignment. Following the pad bytes, if any, is data for the
-leftmost pixel of the second row from the top, and so on. The last row
-has just as many pad bytes after it as the other rows.</para>
-
- <para>In V4L2 each format has an identifier which looks like
-<constant>PIX_FMT_XXX</constant>, defined in the <link
-linkend="videodev">videodev.h</link> header file. These identifiers
-represent <link linkend="v4l2-fourcc">four character (FourCC) codes</link>
-which are also listed below, however they are not the same as those
-used in the Windows world.</para>
-
- <para>For some formats, data is stored in separate, discontiguous
-memory buffers. Those formats are identified by a separate set of FourCC codes
-and are referred to as "multi-planar formats". For example, a YUV422 frame is
-normally stored in one memory buffer, but it can also be placed in two or three
-separate buffers, with Y component in one buffer and CbCr components in another
-in the 2-planar version or with each component in its own buffer in the
-3-planar case. Those sub-buffers are referred to as "planes".</para>
- </section>
-
- <section id="colorspaces">
- <title>Colorspaces</title>
-
- <para>[intro]</para>
-
- <!-- See proposal by Billy Biggs, video4linux-list@redhat.com
-on 11 Oct 2002, subject: "Re: [V4L] Re: v4l2 api", and
-http://vektor.theorem.ca/graphics/ycbcr/ and
-http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html -->
-
- <para>
- <variablelist>
- <varlistentry>
- <term>Gamma Correction</term>
- <listitem>
- <para>[to do]</para>
- <para>E'<subscript>R</subscript> = f(R)</para>
- <para>E'<subscript>G</subscript> = f(G)</para>
- <para>E'<subscript>B</subscript> = f(B)</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Construction of luminance and color-difference
-signals</term>
- <listitem>
- <para>[to do]</para>
- <para>E'<subscript>Y</subscript> =
-Coeff<subscript>R</subscript> E'<subscript>R</subscript>
-+ Coeff<subscript>G</subscript> E'<subscript>G</subscript>
-+ Coeff<subscript>B</subscript> E'<subscript>B</subscript></para>
- <para>(E'<subscript>R</subscript> - E'<subscript>Y</subscript>) = E'<subscript>R</subscript>
-- Coeff<subscript>R</subscript> E'<subscript>R</subscript>
-- Coeff<subscript>G</subscript> E'<subscript>G</subscript>
-- Coeff<subscript>B</subscript> E'<subscript>B</subscript></para>
- <para>(E'<subscript>B</subscript> - E'<subscript>Y</subscript>) = E'<subscript>B</subscript>
-- Coeff<subscript>R</subscript> E'<subscript>R</subscript>
-- Coeff<subscript>G</subscript> E'<subscript>G</subscript>
-- Coeff<subscript>B</subscript> E'<subscript>B</subscript></para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Re-normalized color-difference signals</term>
- <listitem>
- <para>The color-difference signals are scaled back to unity
-range [-0.5;+0.5]:</para>
- <para>K<subscript>B</subscript> = 0.5 / (1 - Coeff<subscript>B</subscript>)</para>
- <para>K<subscript>R</subscript> = 0.5 / (1 - Coeff<subscript>R</subscript>)</para>
- <para>P<subscript>B</subscript> =
-K<subscript>B</subscript> (E'<subscript>B</subscript> - E'<subscript>Y</subscript>) =
- 0.5 (Coeff<subscript>R</subscript> / Coeff<subscript>B</subscript>) E'<subscript>R</subscript>
-+ 0.5 (Coeff<subscript>G</subscript> / Coeff<subscript>B</subscript>) E'<subscript>G</subscript>
-+ 0.5 E'<subscript>B</subscript></para>
- <para>P<subscript>R</subscript> =
-K<subscript>R</subscript> (E'<subscript>R</subscript> - E'<subscript>Y</subscript>) =
- 0.5 E'<subscript>R</subscript>
-+ 0.5 (Coeff<subscript>G</subscript> / Coeff<subscript>R</subscript>) E'<subscript>G</subscript>
-+ 0.5 (Coeff<subscript>B</subscript> / Coeff<subscript>R</subscript>) E'<subscript>B</subscript></para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Quantization</term>
- <listitem>
- <para>[to do]</para>
- <para>Y' = (Lum. Levels - 1) &middot; E'<subscript>Y</subscript> + Lum. Offset</para>
- <para>C<subscript>B</subscript> = (Chrom. Levels - 1)
-&middot; P<subscript>B</subscript> + Chrom. Offset</para>
- <para>C<subscript>R</subscript> = (Chrom. Levels - 1)
-&middot; P<subscript>R</subscript> + Chrom. Offset</para>
- <para>Rounding to the nearest integer and clamping to the range
-[0;255] finally yields the digital color components Y'CbCr
-stored in YUV images.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
- <example>
- <title>ITU-R Rec. BT.601 color conversion</title>
-
- <para>Forward Transformation</para>
-
- <programlisting>
-int ER, EG, EB; /* gamma corrected RGB input [0;255] */
-int Y1, Cb, Cr; /* output [0;255] */
-
-double r, g, b; /* temporaries */
-double y1, pb, pr;
-
-int
-clamp (double x)
-{
- int r = x; /* round to nearest */
-
- if (r &lt; 0) return 0;
- else if (r &gt; 255) return 255;
- else return r;
-}
-
-r = ER / 255.0;
-g = EG / 255.0;
-b = EB / 255.0;
-
-y1 = 0.299 * r + 0.587 * g + 0.114 * b;
-pb = -0.169 * r - 0.331 * g + 0.5 * b;
-pr = 0.5 * r - 0.419 * g - 0.081 * b;
-
-Y1 = clamp (219 * y1 + 16);
-Cb = clamp (224 * pb + 128);
-Cr = clamp (224 * pr + 128);
-
-/* or shorter */
-
-y1 = 0.299 * ER + 0.587 * EG + 0.114 * EB;
-
-Y1 = clamp ( (219 / 255.0) * y1 + 16);
-Cb = clamp (((224 / 255.0) / (2 - 2 * 0.114)) * (EB - y1) + 128);
-Cr = clamp (((224 / 255.0) / (2 - 2 * 0.299)) * (ER - y1) + 128);
- </programlisting>
-
- <para>Inverse Transformation</para>
-
- <programlisting>
-int Y1, Cb, Cr; /* gamma pre-corrected input [0;255] */
-int ER, EG, EB; /* output [0;255] */
-
-double r, g, b; /* temporaries */
-double y1, pb, pr;
-
-int
-clamp (double x)
-{
- int r = x; /* round to nearest */
-
- if (r &lt; 0) return 0;
- else if (r &gt; 255) return 255;
- else return r;
-}
-
-y1 = (255 / 219.0) * (Y1 - 16);
-pb = (255 / 224.0) * (Cb - 128);
-pr = (255 / 224.0) * (Cr - 128);
-
-r = 1.0 * y1 + 0 * pb + 1.402 * pr;
-g = 1.0 * y1 - 0.344 * pb - 0.714 * pr;
-b = 1.0 * y1 + 1.772 * pb + 0 * pr;
-
-ER = clamp (r * 255); /* [ok? one should prob. limit y1,pb,pr] */
-EG = clamp (g * 255);
-EB = clamp (b * 255);
- </programlisting>
- </example>
-
- <table pgwide="1" id="v4l2-colorspace" orient="land">
- <title>enum v4l2_colorspace</title>
- <tgroup cols="11" align="center">
- <colspec align="left" />
- <colspec align="center" />
- <colspec align="left" />
- <colspec colname="cr" />
- <colspec colname="cg" />
- <colspec colname="cb" />
- <colspec colname="wp" />
- <colspec colname="gc" />
- <colspec colname="lum" />
- <colspec colname="qy" />
- <colspec colname="qc" />
- <spanspec namest="cr" nameend="cb" spanname="chrom" />
- <spanspec namest="qy" nameend="qc" spanname="quant" />
- <spanspec namest="lum" nameend="qc" spanname="spam" />
- <thead>
- <row>
- <entry morerows="1">Identifier</entry>
- <entry morerows="1">Value</entry>
- <entry morerows="1">Description</entry>
- <entry spanname="chrom">Chromaticities<footnote>
- <para>The coordinates of the color primaries are
-given in the CIE system (1931)</para>
- </footnote></entry>
- <entry morerows="1">White Point</entry>
- <entry morerows="1">Gamma Correction</entry>
- <entry morerows="1">Luminance E'<subscript>Y</subscript></entry>
- <entry spanname="quant">Quantization</entry>
- </row>
- <row>
- <entry>Red</entry>
- <entry>Green</entry>
- <entry>Blue</entry>
- <entry>Y'</entry>
- <entry>Cb, Cr</entry>
- </row>
- </thead>
- <tbody valign="top">
- <row>
- <entry><constant>V4L2_COLORSPACE_SMPTE170M</constant></entry>
- <entry>1</entry>
- <entry>NTSC/PAL according to <xref linkend="smpte170m" />,
-<xref linkend="itu601" /></entry>
- <entry>x&nbsp;=&nbsp;0.630, y&nbsp;=&nbsp;0.340</entry>
- <entry>x&nbsp;=&nbsp;0.310, y&nbsp;=&nbsp;0.595</entry>
- <entry>x&nbsp;=&nbsp;0.155, y&nbsp;=&nbsp;0.070</entry>
- <entry>x&nbsp;=&nbsp;0.3127, y&nbsp;=&nbsp;0.3290,
- Illuminant D<subscript>65</subscript></entry>
- <entry>E' = 4.5&nbsp;I&nbsp;for&nbsp;I&nbsp;&le;0.018,
-1.099&nbsp;I<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;0.018&nbsp;&lt;&nbsp;I</entry>
- <entry>0.299&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.587&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.114&nbsp;E'<subscript>B</subscript></entry>
- <entry>219&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16</entry>
- <entry>224&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_SMPTE240M</constant></entry>
- <entry>2</entry>
- <entry>1125-Line (US) HDTV, see <xref
-linkend="smpte240m" /></entry>
- <entry>x&nbsp;=&nbsp;0.630, y&nbsp;=&nbsp;0.340</entry>
- <entry>x&nbsp;=&nbsp;0.310, y&nbsp;=&nbsp;0.595</entry>
- <entry>x&nbsp;=&nbsp;0.155, y&nbsp;=&nbsp;0.070</entry>
- <entry>x&nbsp;=&nbsp;0.3127, y&nbsp;=&nbsp;0.3290,
- Illuminant D<subscript>65</subscript></entry>
- <entry>E' = 4&nbsp;I&nbsp;for&nbsp;I&nbsp;&le;0.0228,
-1.1115&nbsp;I<superscript>0.45</superscript>&nbsp;-&nbsp;0.1115&nbsp;for&nbsp;0.0228&nbsp;&lt;&nbsp;I</entry>
- <entry>0.212&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.701&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.087&nbsp;E'<subscript>B</subscript></entry>
- <entry>219&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16</entry>
- <entry>224&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_REC709</constant></entry>
- <entry>3</entry>
- <entry>HDTV and modern devices, see <xref
-linkend="itu709" /></entry>
- <entry>x&nbsp;=&nbsp;0.640, y&nbsp;=&nbsp;0.330</entry>
- <entry>x&nbsp;=&nbsp;0.300, y&nbsp;=&nbsp;0.600</entry>
- <entry>x&nbsp;=&nbsp;0.150, y&nbsp;=&nbsp;0.060</entry>
- <entry>x&nbsp;=&nbsp;0.3127, y&nbsp;=&nbsp;0.3290,
- Illuminant D<subscript>65</subscript></entry>
- <entry>E' = 4.5&nbsp;I&nbsp;for&nbsp;I&nbsp;&le;0.018,
-1.099&nbsp;I<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;0.018&nbsp;&lt;&nbsp;I</entry>
- <entry>0.2125&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.7154&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.0721&nbsp;E'<subscript>B</subscript></entry>
- <entry>219&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16</entry>
- <entry>224&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_BT878</constant></entry>
- <entry>4</entry>
- <entry>Broken Bt878 extents<footnote>
- <para>The ubiquitous Bt878 video capture chip
-quantizes E'<subscript>Y</subscript> to 238 levels, yielding a range
-of Y' = 16 &hellip; 253, unlike Rec. 601 Y' = 16 &hellip;
-235. This is not a typo in the Bt878 documentation, it has been
-implemented in silicon. The chroma extents are unclear.</para>
- </footnote>, <xref linkend="itu601" /></entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>0.299&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.587&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.114&nbsp;E'<subscript>B</subscript></entry>
- <entry><emphasis>237</emphasis>&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16</entry>
- <entry>224&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128 (probably)</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_470_SYSTEM_M</constant></entry>
- <entry>5</entry>
- <entry>M/NTSC<footnote>
- <para>No identifier exists for M/PAL which uses
-the chromaticities of M/NTSC, the remaining parameters are equal to B and
-G/PAL.</para>
- </footnote> according to <xref linkend="itu470" />, <xref
- linkend="itu601" /></entry>
- <entry>x&nbsp;=&nbsp;0.67, y&nbsp;=&nbsp;0.33</entry>
- <entry>x&nbsp;=&nbsp;0.21, y&nbsp;=&nbsp;0.71</entry>
- <entry>x&nbsp;=&nbsp;0.14, y&nbsp;=&nbsp;0.08</entry>
- <entry>x&nbsp;=&nbsp;0.310, y&nbsp;=&nbsp;0.316, Illuminant C</entry>
- <entry>?</entry>
- <entry>0.299&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.587&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.114&nbsp;E'<subscript>B</subscript></entry>
- <entry>219&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16</entry>
- <entry>224&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant></entry>
- <entry>6</entry>
- <entry>625-line PAL and SECAM systems according to <xref
-linkend="itu470" />, <xref linkend="itu601" /></entry>
- <entry>x&nbsp;=&nbsp;0.64, y&nbsp;=&nbsp;0.33</entry>
- <entry>x&nbsp;=&nbsp;0.29, y&nbsp;=&nbsp;0.60</entry>
- <entry>x&nbsp;=&nbsp;0.15, y&nbsp;=&nbsp;0.06</entry>
- <entry>x&nbsp;=&nbsp;0.313, y&nbsp;=&nbsp;0.329,
-Illuminant D<subscript>65</subscript></entry>
- <entry>?</entry>
- <entry>0.299&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.587&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.114&nbsp;E'<subscript>B</subscript></entry>
- <entry>219&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16</entry>
- <entry>224&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_JPEG</constant></entry>
- <entry>7</entry>
- <entry>JPEG Y'CbCr, see <xref linkend="jfif" />, <xref linkend="itu601" /></entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>?</entry>
- <entry>0.299&nbsp;E'<subscript>R</subscript>
-+&nbsp;0.587&nbsp;E'<subscript>G</subscript>
-+&nbsp;0.114&nbsp;E'<subscript>B</subscript></entry>
- <entry>256&nbsp;E'<subscript>Y</subscript>&nbsp;+&nbsp;16<footnote>
- <para>Note JFIF quantizes
-Y'P<subscript>B</subscript>P<subscript>R</subscript> in range [0;+1] and
-[-0.5;+0.5] to <emphasis>257</emphasis> levels, however Y'CbCr signals
-are still clamped to [0;255].</para>
- </footnote></entry>
- <entry>256&nbsp;P<subscript>B,R</subscript>&nbsp;+&nbsp;128</entry>
- </row>
- <row>
- <entry><constant>V4L2_COLORSPACE_SRGB</constant></entry>
- <entry>8</entry>
- <entry>[?]</entry>
- <entry>x&nbsp;=&nbsp;0.640, y&nbsp;=&nbsp;0.330</entry>
- <entry>x&nbsp;=&nbsp;0.300, y&nbsp;=&nbsp;0.600</entry>
- <entry>x&nbsp;=&nbsp;0.150, y&nbsp;=&nbsp;0.060</entry>
- <entry>x&nbsp;=&nbsp;0.3127, y&nbsp;=&nbsp;0.3290,
- Illuminant D<subscript>65</subscript></entry>
- <entry>E' = 4.5&nbsp;I&nbsp;for&nbsp;I&nbsp;&le;0.018,
-1.099&nbsp;I<superscript>0.45</superscript>&nbsp;-&nbsp;0.099&nbsp;for&nbsp;0.018&nbsp;&lt;&nbsp;I</entry>
- <entry spanname="spam">n/a</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="pixfmt-indexed">
- <title>Indexed Format</title>
-
- <para>In this format each pixel is represented by an 8 bit index
-into a 256 entry ARGB palette. It is intended for <link
-linkend="osd">Video Output Overlays</link> only. There are no ioctls to
-access the palette, this must be done with ioctls of the Linux framebuffer API.</para>
-
- <table pgwide="0" frame="none">
- <title>Indexed Image Format</title>
- <tgroup cols="37" align="center">
- <colspec colname="id" align="left" />
- <colspec colname="fourcc" />
- <colspec colname="bit" />
-
- <colspec colnum="4" colname="b07" align="center" />
- <colspec colnum="5" colname="b06" align="center" />
- <colspec colnum="6" colname="b05" align="center" />
- <colspec colnum="7" colname="b04" align="center" />
- <colspec colnum="8" colname="b03" align="center" />
- <colspec colnum="9" colname="b02" align="center" />
- <colspec colnum="10" colname="b01" align="center" />
- <colspec colnum="11" colname="b00" align="center" />
-
- <spanspec namest="b07" nameend="b00" spanname="b0" />
- <spanspec namest="b17" nameend="b10" spanname="b1" />
- <spanspec namest="b27" nameend="b20" spanname="b2" />
- <spanspec namest="b37" nameend="b30" spanname="b3" />
- <thead>
- <row>
- <entry>Identifier</entry>
- <entry>Code</entry>
- <entry>&nbsp;</entry>
- <entry spanname="b0">Byte&nbsp;0</entry>
- </row>
- <row>
- <entry>&nbsp;</entry>
- <entry>&nbsp;</entry>
- <entry>Bit</entry>
- <entry>7</entry>
- <entry>6</entry>
- <entry>5</entry>
- <entry>4</entry>
- <entry>3</entry>
- <entry>2</entry>
- <entry>1</entry>
- <entry>0</entry>
- </row>
- </thead>
- <tbody valign="top">
- <row id="V4L2-PIX-FMT-PAL8">
- <entry><constant>V4L2_PIX_FMT_PAL8</constant></entry>
- <entry>'PAL8'</entry>
- <entry></entry>
- <entry>i<subscript>7</subscript></entry>
- <entry>i<subscript>6</subscript></entry>
- <entry>i<subscript>5</subscript></entry>
- <entry>i<subscript>4</subscript></entry>
- <entry>i<subscript>3</subscript></entry>
- <entry>i<subscript>2</subscript></entry>
- <entry>i<subscript>1</subscript></entry>
- <entry>i<subscript>0</subscript></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="pixfmt-rgb">
- <title>RGB Formats</title>
-
- &sub-packed-rgb;
- &sub-sbggr8;
- &sub-sgbrg8;
- &sub-sgrbg8;
- &sub-srggb8;
- &sub-sbggr16;
- &sub-srggb10;
- &sub-srggb10dpcm8;
- &sub-srggb12;
- </section>
-
- <section id="yuv-formats">
- <title>YUV Formats</title>
-
- <para>YUV is the format native to TV broadcast and composite video
-signals. It separates the brightness information (Y) from the color
-information (U and V or Cb and Cr). The color information consists of
-red and blue <emphasis>color difference</emphasis> signals, this way
-the green component can be reconstructed by subtracting from the
-brightness component. See <xref linkend="colorspaces" /> for conversion
-examples. YUV was chosen because early television would only transmit
-brightness information. To add color in a way compatible with existing
-receivers a new signal carrier was added to transmit the color
-difference signals. Secondary in the YUV format the U and V components
-usually have lower resolution than the Y component. This is an analog
-video compression technique taking advantage of a property of the
-human visual system, being more sensitive to brightness
-information.</para>
-
- &sub-packed-yuv;
- &sub-grey;
- &sub-y10;
- &sub-y12;
- &sub-y10b;
- &sub-y16;
- &sub-yuyv;
- &sub-uyvy;
- &sub-yvyu;
- &sub-vyuy;
- &sub-y41p;
- &sub-yuv420;
- &sub-yuv420m;
- &sub-yuv410;
- &sub-yuv422p;
- &sub-yuv411p;
- &sub-nv12;
- &sub-nv12m;
- &sub-nv12mt;
- &sub-nv16;
- &sub-nv24;
- &sub-m420;
- </section>
-
- <section>
- <title>Compressed Formats</title>
-
- <table pgwide="1" frame="none" id="compressed-formats">
- <title>Compressed Image Formats</title>
- <tgroup cols="3" align="left">
- &cs-def;
- <thead>
- <row>
- <entry>Identifier</entry>
- <entry>Code</entry>
- <entry>Details</entry>
- </row>
- </thead>
- <tbody valign="top">
- <row id="V4L2-PIX-FMT-JPEG">
- <entry><constant>V4L2_PIX_FMT_JPEG</constant></entry>
- <entry>'JPEG'</entry>
- <entry>TBD. See also &VIDIOC-G-JPEGCOMP;,
- &VIDIOC-S-JPEGCOMP;.</entry>
- </row>
- <row id="V4L2-PIX-FMT-MPEG">
- <entry><constant>V4L2_PIX_FMT_MPEG</constant></entry>
- <entry>'MPEG'</entry>
- <entry>MPEG multiplexed stream. The actual format is determined by
-extended control <constant>V4L2_CID_MPEG_STREAM_TYPE</constant>, see
-<xref linkend="mpeg-control-id" />.</entry>
- </row>
- <row id="V4L2-PIX-FMT-H264">
- <entry><constant>V4L2_PIX_FMT_H264</constant></entry>
- <entry>'H264'</entry>
- <entry>H264 video elementary stream with start codes.</entry>
- </row>
- <row id="V4L2-PIX-FMT-H264-NO-SC">
- <entry><constant>V4L2_PIX_FMT_H264_NO_SC</constant></entry>
- <entry>'AVC1'</entry>
- <entry>H264 video elementary stream without start codes.</entry>
- </row>
- <row id="V4L2-PIX-FMT-H263">
- <entry><constant>V4L2_PIX_FMT_H263</constant></entry>
- <entry>'H263'</entry>
- <entry>H263 video elementary stream.</entry>
- </row>
- <row id="V4L2-PIX-FMT-MPEG1">
- <entry><constant>V4L2_PIX_FMT_MPEG1</constant></entry>
- <entry>'MPG1'</entry>
- <entry>MPEG1 video elementary stream.</entry>
- </row>
- <row id="V4L2-PIX-FMT-MPEG2">
- <entry><constant>V4L2_PIX_FMT_MPEG2</constant></entry>
- <entry>'MPG2'</entry>
- <entry>MPEG2 video elementary stream.</entry>
- </row>
- <row id="V4L2-PIX-FMT-MPEG4">
- <entry><constant>V4L2_PIX_FMT_MPEG4</constant></entry>
- <entry>'MPG4'</entry>
- <entry>MPEG4 video elementary stream.</entry>
- </row>
- <row id="V4L2-PIX-FMT-XVID">
- <entry><constant>V4L2_PIX_FMT_XVID</constant></entry>
- <entry>'XVID'</entry>
- <entry>Xvid video elementary stream.</entry>
- </row>
- <row id="V4L2-PIX-FMT-VC1-ANNEX-G">
- <entry><constant>V4L2_PIX_FMT_VC1_ANNEX_G</constant></entry>
- <entry>'VC1G'</entry>
- <entry>VC1, SMPTE 421M Annex G compliant stream.</entry>
- </row>
- <row id="V4L2-PIX-FMT-VC1-ANNEX-L">
- <entry><constant>V4L2_PIX_FMT_VC1_ANNEX_L</constant></entry>
- <entry>'VC1L'</entry>
- <entry>VC1, SMPTE 421M Annex L compliant stream.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="pixfmt-reserved">
- <title>Reserved Format Identifiers</title>
-
- <para>These formats are not defined by this specification, they
-are just listed for reference and to avoid naming conflicts. If you
-want to register your own format, send an e-mail to the linux-media mailing
-list &v4l-ml; for inclusion in the <filename>videodev2.h</filename>
-file. If you want to share your format with other developers add a
-link to your documentation and send a copy to the linux-media mailing list
-for inclusion in this section. If you think your format should be listed
-in a standard format section please make a proposal on the linux-media mailing
-list.</para>
-
- <table pgwide="1" frame="none" id="reserved-formats">
- <title>Reserved Image Formats</title>
- <tgroup cols="3" align="left">
- &cs-def;
- <thead>
- <row>
- <entry>Identifier</entry>
- <entry>Code</entry>
- <entry>Details</entry>
- </row>
- </thead>
- <tbody valign="top">
- <row id="V4L2-PIX-FMT-DV">
- <entry><constant>V4L2_PIX_FMT_DV</constant></entry>
- <entry>'dvsd'</entry>
- <entry>unknown</entry>
- </row>
- <row id="V4L2-PIX-FMT-ET61X251">
- <entry><constant>V4L2_PIX_FMT_ET61X251</constant></entry>
- <entry>'E625'</entry>
- <entry>Compressed format of the ET61X251 driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-HI240">
- <entry><constant>V4L2_PIX_FMT_HI240</constant></entry>
- <entry>'HI24'</entry>
- <entry><para>8 bit RGB format used by the BTTV driver.</para></entry>
- </row>
- <row id="V4L2-PIX-FMT-HM12">
- <entry><constant>V4L2_PIX_FMT_HM12</constant></entry>
- <entry>'HM12'</entry>
- <entry><para>YUV 4:2:0 format used by the
-IVTV driver, <ulink url="http://www.ivtvdriver.org/">
-http://www.ivtvdriver.org/</ulink></para><para>The format is documented in the
-kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.hm12</filename>
-</para></entry>
- </row>
- <row id="V4L2-PIX-FMT-CPIA1">
- <entry><constant>V4L2_PIX_FMT_CPIA1</constant></entry>
- <entry>'CPIA'</entry>
- <entry>YUV format used by the gspca cpia1 driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-JPGL">
- <entry><constant>V4L2_PIX_FMT_JPGL</constant></entry>
- <entry>'JPGL'</entry>
- <entry>JPEG-Light format (Pegasus Lossless JPEG)
- used in Divio webcams NW 80x.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SPCA501">
- <entry><constant>V4L2_PIX_FMT_SPCA501</constant></entry>
- <entry>'S501'</entry>
- <entry>YUYV per line used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SPCA505">
- <entry><constant>V4L2_PIX_FMT_SPCA505</constant></entry>
- <entry>'S505'</entry>
- <entry>YYUV per line used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SPCA508">
- <entry><constant>V4L2_PIX_FMT_SPCA508</constant></entry>
- <entry>'S508'</entry>
- <entry>YUVY per line used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SPCA561">
- <entry><constant>V4L2_PIX_FMT_SPCA561</constant></entry>
- <entry>'S561'</entry>
- <entry>Compressed GBRG Bayer format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-PAC207">
- <entry><constant>V4L2_PIX_FMT_PAC207</constant></entry>
- <entry>'P207'</entry>
- <entry>Compressed BGGR Bayer format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-MR97310A">
- <entry><constant>V4L2_PIX_FMT_MR97310A</constant></entry>
- <entry>'M310'</entry>
- <entry>Compressed BGGR Bayer format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-JL2005BCD">
- <entry><constant>V4L2_PIX_FMT_JL2005BCD</constant></entry>
- <entry>'JL20'</entry>
- <entry>JPEG compressed RGGB Bayer format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-OV511">
- <entry><constant>V4L2_PIX_FMT_OV511</constant></entry>
- <entry>'O511'</entry>
- <entry>OV511 JPEG format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-OV518">
- <entry><constant>V4L2_PIX_FMT_OV518</constant></entry>
- <entry>'O518'</entry>
- <entry>OV518 JPEG format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-PJPG">
- <entry><constant>V4L2_PIX_FMT_PJPG</constant></entry>
- <entry>'PJPG'</entry>
- <entry>Pixart 73xx JPEG format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SE401">
- <entry><constant>V4L2_PIX_FMT_SE401</constant></entry>
- <entry>'S401'</entry>
- <entry>Compressed RGB format used by the gspca se401 driver</entry>
- </row>
- <row id="V4L2-PIX-FMT-SQ905C">
- <entry><constant>V4L2_PIX_FMT_SQ905C</constant></entry>
- <entry>'905C'</entry>
- <entry>Compressed RGGB bayer format used by the gspca driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-MJPEG">
- <entry><constant>V4L2_PIX_FMT_MJPEG</constant></entry>
- <entry>'MJPG'</entry>
- <entry>Compressed format used by the Zoran driver</entry>
- </row>
- <row id="V4L2-PIX-FMT-PWC1">
- <entry><constant>V4L2_PIX_FMT_PWC1</constant></entry>
- <entry>'PWC1'</entry>
- <entry>Compressed format of the PWC driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-PWC2">
- <entry><constant>V4L2_PIX_FMT_PWC2</constant></entry>
- <entry>'PWC2'</entry>
- <entry>Compressed format of the PWC driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SN9C10X">
- <entry><constant>V4L2_PIX_FMT_SN9C10X</constant></entry>
- <entry>'S910'</entry>
- <entry>Compressed format of the SN9C102 driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SN9C20X-I420">
- <entry><constant>V4L2_PIX_FMT_SN9C20X_I420</constant></entry>
- <entry>'S920'</entry>
- <entry>YUV 4:2:0 format of the gspca sn9c20x driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-SN9C2028">
- <entry><constant>V4L2_PIX_FMT_SN9C2028</constant></entry>
- <entry>'SONX'</entry>
- <entry>Compressed GBRG bayer format of the gspca sn9c2028 driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-STV0680">
- <entry><constant>V4L2_PIX_FMT_STV0680</constant></entry>
- <entry>'S680'</entry>
- <entry>Bayer format of the gspca stv0680 driver.</entry>
- </row>
- <row id="V4L2-PIX-FMT-WNVA">
- <entry><constant>V4L2_PIX_FMT_WNVA</constant></entry>
- <entry>'WNVA'</entry>
- <entry><para>Used by the Winnov Videum driver, <ulink
-url="http://www.thedirks.org/winnov/">
-http://www.thedirks.org/winnov/</ulink></para></entry>
- </row>
- <row id="V4L2-PIX-FMT-TM6000">
- <entry><constant>V4L2_PIX_FMT_TM6000</constant></entry>
- <entry>'TM60'</entry>
- <entry><para>Used by Trident tm6000</para></entry>
- </row>
- <row id="V4L2-PIX-FMT-CIT-YYVYUY">
- <entry><constant>V4L2_PIX_FMT_CIT_YYVYUY</constant></entry>
- <entry>'CITV'</entry>
- <entry><para>Used by xirlink CIT, found at IBM webcams.</para>
- <para>Uses one line of Y then 1 line of VYUY</para>
- </entry>
- </row>
- <row id="V4L2-PIX-FMT-KONICA420">
- <entry><constant>V4L2_PIX_FMT_KONICA420</constant></entry>
- <entry>'KONI'</entry>
- <entry><para>Used by Konica webcams.</para>
- <para>YUV420 planar in blocks of 256 pixels.</para>
- </entry>
- </row>
- <row id="V4L2-PIX-FMT-YYUV">
- <entry><constant>V4L2_PIX_FMT_YYUV</constant></entry>
- <entry>'YYUV'</entry>
- <entry>unknown</entry>
- </row>
- <row id="V4L2-PIX-FMT-Y4">
- <entry><constant>V4L2_PIX_FMT_Y4</constant></entry>
- <entry>'Y04 '</entry>
- <entry>Old 4-bit greyscale format. Only the most significant 4 bits of each byte are used,
-the other bits are set to 0.</entry>
- </row>
- <row id="V4L2-PIX-FMT-Y6">
- <entry><constant>V4L2_PIX_FMT_Y6</constant></entry>
- <entry>'Y06 '</entry>
- <entry>Old 6-bit greyscale format. Only the most significant 6 bits of each byte are used,
-the other bits are set to 0.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>