<entry>This information supplements the
<structfield>colorspace</structfield> and must be set by the driver for
capture streams and by the application for output streams,
+see <xref linkend="colorspaces" />.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-xfer-func;</entry>
+ <entry><structfield>xfer_func</structfield></entry>
+ <entry>This information supplements the
+<structfield>colorspace</structfield> and must be set by the driver for
+capture streams and by the application for output streams,
see <xref linkend="colorspaces" />.</entry>
</row>
</tbody>
<row>
<entry>__u16</entry>
<entry><structfield>reserved[6]</structfield></entry>
- <entry>Reserved for future extensions. Should be zeroed by the
- application.</entry>
+ <entry>Reserved for future extensions. Should be zeroed by drivers and
+ applications.</entry>
</row>
</tbody>
</tgroup>
<entry>This information supplements the
<structfield>colorspace</structfield> and must be set by the driver for
capture streams and by the application for output streams,
+see <xref linkend="colorspaces" />.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-xfer-func;</entry>
+ <entry><structfield>xfer_func</structfield></entry>
+ <entry>This information supplements the
+<structfield>colorspace</structfield> and must be set by the driver for
+capture streams and by the application for output streams,
see <xref linkend="colorspaces" />.</entry>
</row>
<row>
<entry>__u8</entry>
- <entry><structfield>reserved[8]</structfield></entry>
- <entry>Reserved for future extensions. Should be zeroed by the
- application.</entry>
+ <entry><structfield>reserved[7]</structfield></entry>
+ <entry>Reserved for future extensions. Should be zeroed by drivers
+ and applications.</entry>
</row>
</tbody>
</tgroup>
<section>
<title>Defining Colorspaces in V4L2</title>
- <para>In V4L2 colorspaces are defined by three values. The first is the colorspace
-identifier (&v4l2-colorspace;) which defines the chromaticities, the transfer
+ <para>In V4L2 colorspaces are defined by four values. The first is the colorspace
+identifier (&v4l2-colorspace;) which defines the chromaticities, the default transfer
function, the default Y'CbCr encoding and the default quantization method. The second
-is the Y'CbCr encoding identifier (&v4l2-ycbcr-encoding;) to specify non-standard
-Y'CbCr encodings and the third is the quantization identifier (&v4l2-quantization;)
-to specify non-standard quantization methods. Most of the time only the colorspace
-field of &v4l2-pix-format; or &v4l2-pix-format-mplane; needs to be filled in. Note
-that the default R'G'B' quantization is full range for all colorspaces except for
-BT.2020 which uses limited range R'G'B' quantization.</para>
+is the transfer function identifier (&v4l2-xfer-func;) to specify non-standard
+transfer functions. The third is the Y'CbCr encoding identifier (&v4l2-ycbcr-encoding;)
+to specify non-standard Y'CbCr encodings and the fourth is the quantization identifier
+(&v4l2-quantization;) to specify non-standard quantization methods. Most of the time
+only the colorspace field of &v4l2-pix-format; or &v4l2-pix-format-mplane; needs to
+be filled in. Note that the default R'G'B' quantization is full range for all
+colorspaces except for BT.2020 which uses limited range R'G'B' quantization.</para>
<table pgwide="1" frame="none" id="v4l2-colorspace">
<title>V4L2 Colorspaces</title>
</row>
</thead>
<tbody valign="top">
+ <row>
+ <entry><constant>V4L2_COLORSPACE_DEFAULT</constant></entry>
+ <entry>The default colorspace. This can be used by applications to let the
+ driver fill in the colorspace.</entry>
+ </row>
<row>
<entry><constant>V4L2_COLORSPACE_SMPTE170M</constant></entry>
<entry>See <xref linkend="col-smpte-170m" />.</entry>
<entry><constant>V4L2_COLORSPACE_BT2020</constant></entry>
<entry>See <xref linkend="col-bt2020" />.</entry>
</row>
+ <row>
+ <entry><constant>V4L2_COLORSPACE_DCI_P3</constant></entry>
+ <entry>See <xref linkend="col-dcip3" />.</entry>
+ </row>
<row>
<entry><constant>V4L2_COLORSPACE_SMPTE240M</constant></entry>
<entry>See <xref linkend="col-smpte-240m" />.</entry>
<entry><constant>V4L2_COLORSPACE_JPEG</constant></entry>
<entry>See <xref linkend="col-jpeg" />.</entry>
</row>
+ <row>
+ <entry><constant>V4L2_COLORSPACE_RAW</constant></entry>
+ <entry>The raw colorspace. This is used for raw image capture where
+ the image is minimally processed and is using the internal colorspace
+ of the device. The software that processes an image using this
+ 'colorspace' will have to know the internals of the capture device.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <table pgwide="1" frame="none" id="v4l2-xfer-func">
+ <title>V4L2 Transfer Function</title>
+ <tgroup cols="2" align="left">
+ &cs-def;
+ <thead>
+ <row>
+ <entry>Identifier</entry>
+ <entry>Details</entry>
+ </row>
+ </thead>
+ <tbody valign="top">
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_DEFAULT</constant></entry>
+ <entry>Use the default transfer function as defined by the colorspace.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_709</constant></entry>
+ <entry>Use the Rec. 709 transfer function.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_SRGB</constant></entry>
+ <entry>Use the sRGB transfer function.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_ADOBERGB</constant></entry>
+ <entry>Use the AdobeRGB transfer function.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_SMPTE240M</constant></entry>
+ <entry>Use the SMPTE 240M transfer function.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_NONE</constant></entry>
+ <entry>Do not use a transfer function (i.e. use linear RGB values).</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_DCI_P3</constant></entry>
+ <entry>Use the DCI-P3 transfer function.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_XFER_FUNC_SMPTE2084</constant></entry>
+ <entry>Use the SMPTE 2084 transfer function.</entry>
+ </row>
</tbody>
</tgroup>
</table>
<section id="col-smpte-170m">
<title>Colorspace SMPTE 170M (<constant>V4L2_COLORSPACE_SMPTE170M</constant>)</title>
<para>The <xref linkend="smpte170m" /> standard defines the colorspace used by NTSC and PAL and by SDTV
-in general. The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
+in general. The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and
the white reference are:</para>
<table frame="none">
<section id="col-rec709">
<title>Colorspace Rec. 709 (<constant>V4L2_COLORSPACE_REC709</constant>)</title>
- <para>The <xref linkend="itu709" /> standard defines the colorspace used by HDTV in general. The default
+ <para>The <xref linkend="itu709" /> standard defines the colorspace used by HDTV in general.
+The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>. The default
Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_709</constant>. The default Y'CbCr quantization is
limited range. The chromaticities of the primary colors and the white reference are:</para>
<table frame="none">
<section id="col-srgb">
<title>Colorspace sRGB (<constant>V4L2_COLORSPACE_SRGB</constant>)</title>
- <para>The <xref linkend="srgb" /> standard defines the colorspace used by most webcams and computer graphics. The
-default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_SYCC</constant>. The default Y'CbCr quantization
-is full range. The chromaticities of the primary colors and the white reference are:</para>
+ <para>The <xref linkend="srgb" /> standard defines the colorspace used by most webcams
+and computer graphics. The default transfer function is <constant>V4L2_XFER_FUNC_SRGB</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_SYCC</constant>. The default Y'CbCr
+quantization is full range. The chromaticities of the primary colors and the white
+reference are:</para>
<table frame="none">
<title>sRGB Chromaticities</title>
<tgroup cols="3" align="left">
<title>Colorspace Adobe RGB (<constant>V4L2_COLORSPACE_ADOBERGB</constant>)</title>
<para>The <xref linkend="adobergb" /> standard defines the colorspace used by computer graphics
that use the AdobeRGB colorspace. This is also known as the <xref linkend="oprgb" /> standard.
+The default transfer function is <constant>V4L2_XFER_FUNC_ADOBERGB</constant>.
The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>. The default Y'CbCr
quantization is limited range. The chromaticities of the primary colors and the white reference
are:</para>
<section id="col-bt2020">
<title>Colorspace BT.2020 (<constant>V4L2_COLORSPACE_BT2020</constant>)</title>
<para>The <xref linkend="itu2020" /> standard defines the colorspace used by Ultra-high definition
-television (UHDTV). The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_BT2020</constant>.
+television (UHDTV). The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_BT2020</constant>.
The default R'G'B' quantization is limited range (!), and so is the default Y'CbCr quantization.
The chromaticities of the primary colors and the white reference are:</para>
<table frame="none">
clamped to the range [-0.5…0.5]. The Yc'CbcCrc quantization is limited range.</para>
</section>
+ <section id="col-dcip3">
+ <title>Colorspace DCI-P3 (<constant>V4L2_COLORSPACE_DCI_P3</constant>)</title>
+ <para>The <xref linkend="smpte431" /> standard defines the colorspace used by cinema
+projectors that use the DCI-P3 colorspace.
+The default transfer function is <constant>V4L2_XFER_FUNC_DCI_P3</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_709</constant>. Note that this
+colorspace does not specify a Y'CbCr encoding since it is not meant to be encoded
+to Y'CbCr. So this default Y'CbCr encoding was picked because it is the HDTV
+encoding. The default Y'CbCr quantization is limited range. The chromaticities of
+the primary colors and the white reference are:</para>
+ <table frame="none">
+ <title>DCI-P3 Chromaticities</title>
+ <tgroup cols="3" align="left">
+ &cs-str;
+ <thead>
+ <row>
+ <entry>Color</entry>
+ <entry>x</entry>
+ <entry>y</entry>
+ </row>
+ </thead>
+ <tbody valign="top">
+ <row>
+ <entry>Red</entry>
+ <entry>0.6800</entry>
+ <entry>0.3200</entry>
+ </row>
+ <row>
+ <entry>Green</entry>
+ <entry>0.2650</entry>
+ <entry>0.6900</entry>
+ </row>
+ <row>
+ <entry>Blue</entry>
+ <entry>0.1500</entry>
+ <entry>0.0600</entry>
+ </row>
+ <row>
+ <entry>White Reference</entry>
+ <entry>0.3140</entry>
+ <entry>0.3510</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ <variablelist>
+ <varlistentry>
+ <term>Transfer function:</term>
+ <listitem>
+ <para>L' = L<superscript>1/2.6</superscript></para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Inverse Transfer function:</term>
+ <listitem>
+ <para>L = L'<superscript>2.6</superscript></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <para>Y'CbCr encoding is not specified. V4L2 defaults to Rec. 709.</para>
+ </section>
+
<section id="col-smpte-240m">
<title>Colorspace SMPTE 240M (<constant>V4L2_COLORSPACE_SMPTE240M</constant>)</title>
- <para>The <xref linkend="smpte240m" /> standard was an interim standard used during the early days of HDTV (1988-1998).
-It has been superseded by Rec. 709. The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_SMPTE240M</constant>.
+ <para>The <xref linkend="smpte240m" /> standard was an interim standard used during
+the early days of HDTV (1988-1998). It has been superseded by Rec. 709.
+The default transfer function is <constant>V4L2_XFER_FUNC_SMPTE240M</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_SMPTE240M</constant>.
The default Y'CbCr quantization is limited range. The chromaticities of the primary colors and the
white reference are:</para>
<table frame="none">
<section id="col-sysm">
<title>Colorspace NTSC 1953 (<constant>V4L2_COLORSPACE_470_SYSTEM_M</constant>)</title>
<para>This standard defines the colorspace used by NTSC in 1953. In practice this
-colorspace is obsolete and SMPTE 170M should be used instead. The default Y'CbCr encoding
-is <constant>V4L2_YCBCR_ENC_601</constant>. The default Y'CbCr quantization is limited range.
+colorspace is obsolete and SMPTE 170M should be used instead.
+The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
+The default Y'CbCr quantization is limited range.
The chromaticities of the primary colors and the white reference are:</para>
<table frame="none">
<title>NTSC 1953 Chromaticities</title>
<section id="col-sysbg">
<title>Colorspace EBU Tech. 3213 (<constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant>)</title>
<para>The <xref linkend="tech3213" /> standard defines the colorspace used by PAL/SECAM in 1975. In practice this
-colorspace is obsolete and SMPTE 170M should be used instead. The default Y'CbCr encoding
-is <constant>V4L2_YCBCR_ENC_601</constant>. The default Y'CbCr quantization is limited range.
+colorspace is obsolete and SMPTE 170M should be used instead.
+The default transfer function is <constant>V4L2_XFER_FUNC_709</constant>.
+The default Y'CbCr encoding is <constant>V4L2_YCBCR_ENC_601</constant>.
+The default Y'CbCr quantization is limited range.
The chromaticities of the primary colors and the white reference are:</para>
<table frame="none">
<title>EBU Tech. 3213 Chromaticities</title>
<section id="col-jpeg">
<title>Colorspace JPEG (<constant>V4L2_COLORSPACE_JPEG</constant>)</title>
<para>This colorspace defines the colorspace used by most (Motion-)JPEG formats. The chromaticities
-of the primary colors and the white reference are identical to sRGB. The Y'CbCr encoding is
+of the primary colors and the white reference are identical to sRGB. The transfer
+function use is <constant>V4L2_XFER_FUNC_SRGB</constant>. The Y'CbCr encoding is
<constant>V4L2_YCBCR_ENC_601</constant> with full range quantization where
Y' is scaled to [0…255] and Cb/Cr are scaled to [-128…128] and
then clipped to [-128…127].</para>
</section>
+ <section>
+ <title>Detailed Transfer Function Descriptions</title>
+ <section id="xf-smpte-2084">
+ <title>Transfer Function SMPTE 2084 (<constant>V4L2_XFER_FUNC_SMPTE2084</constant>)</title>
+ <para>The <xref linkend="smpte2084" /> standard defines the transfer function used by
+High Dynamic Range content.</para>
+ <variablelist>
+ <varlistentry>
+ <term>Constants:</term>
+ <listitem>
+ <para>m1 = (2610 / 4096) / 4</para>
+ <para>m2 = (2523 / 4096) * 128</para>
+ <para>c1 = 3424 / 4096</para>
+ <para>c2 = (2413 / 4096) * 32</para>
+ <para>c3 = (2392 / 4096) * 32</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>Transfer function:</term>
+ <listitem>
+ <para>L' = ((c1 + c2 * L<superscript>m1</superscript>) / (1 + c3 * L<superscript>m1</superscript>))<superscript>m2</superscript></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>Inverse Transfer function:</term>
+ <listitem>
+ <para>L = (max(L'<superscript>1/m2</superscript> - c1, 0) / (c2 - c3 * L'<superscript>1/m2</superscript>))<superscript>1/m1</superscript></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+ </section>
+
<section id="pixfmt-indexed">
<title>Indexed Format</title>
&sub-y12;
&sub-y10b;
&sub-y16;
+ &sub-y16-be;
&sub-uv8;
&sub-yuyv;
&sub-uyvy;
<section id="sdr-formats">
<title>SDR Formats</title>
- <para>These formats are used for <link linkend="sdr">SDR Capture</link>
+ <para>These formats are used for <link linkend="sdr">SDR</link>
interface only.</para>
&sub-sdr-cu08;
Code Review / kvmfornfv.git / blobdiff