<entry>b<subscript>1</subscript></entry>
<entry>b<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-RGB444">
- <entry><constant>V4L2_PIX_FMT_RGB444</constant></entry>
- <entry>'R444'</entry>
+ <row id="V4L2-PIX-FMT-ARGB444">
+ <entry><constant>V4L2_PIX_FMT_ARGB444</constant></entry>
+ <entry>'AR12'</entry>
<entry></entry>
<entry>g<subscript>3</subscript></entry>
<entry>g<subscript>2</subscript></entry>
<entry>r<subscript>1</subscript></entry>
<entry>r<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-RGB555">
- <entry><constant>V4L2_PIX_FMT_RGB555</constant></entry>
- <entry>'RGBO'</entry>
+ <row id="V4L2-PIX-FMT-XRGB444">
+ <entry><constant>V4L2_PIX_FMT_XRGB444</constant></entry>
+ <entry>'XR12'</entry>
+ <entry></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-ARGB555">
+ <entry><constant>V4L2_PIX_FMT_ARGB555</constant></entry>
+ <entry>'AR15'</entry>
<entry></entry>
<entry>g<subscript>2</subscript></entry>
<entry>g<subscript>1</subscript></entry>
<entry>g<subscript>4</subscript></entry>
<entry>g<subscript>3</subscript></entry>
</row>
+ <row id="V4L2-PIX-FMT-XRGB555">
+ <entry><constant>V4L2_PIX_FMT_XRGB555</constant></entry>
+ <entry>'XR15'</entry>
+ <entry></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ </row>
<row id="V4L2-PIX-FMT-RGB565">
<entry><constant>V4L2_PIX_FMT_RGB565</constant></entry>
<entry>'RGBP'</entry>
<entry>b<subscript>1</subscript></entry>
<entry>b<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-BGR32">
- <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry>
- <entry>'BGR4'</entry>
+ <row id="V4L2-PIX-FMT-ABGR32">
+ <entry><constant>V4L2_PIX_FMT_ABGR32</constant></entry>
+ <entry>'AR24'</entry>
<entry></entry>
<entry>b<subscript>7</subscript></entry>
<entry>b<subscript>6</subscript></entry>
<entry>a<subscript>1</subscript></entry>
<entry>a<subscript>0</subscript></entry>
</row>
- <row id="V4L2-PIX-FMT-RGB32">
- <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry>
- <entry>'RGB4'</entry>
+ <row id="V4L2-PIX-FMT-XBGR32">
+ <entry><constant>V4L2_PIX_FMT_XBGR32</constant></entry>
+ <entry>'XR24'</entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ </row>
+ <row id="V4L2-PIX-FMT-ARGB32">
+ <entry><constant>V4L2_PIX_FMT_ARGB32</constant></entry>
+ <entry>'AX24'</entry>
<entry></entry>
<entry>a<subscript>7</subscript></entry>
<entry>a<subscript>6</subscript></entry>
<entry>b<subscript>1</subscript></entry>
<entry>b<subscript>0</subscript></entry>
</row>
+ <row id="V4L2-PIX-FMT-XRGB32">
+ <entry><constant>V4L2_PIX_FMT_XRGB32</constant></entry>
+ <entry>'BX24'</entry>
+ <entry></entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry>-</entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ </row>
</tbody>
</tgroup>
</table>
- <para>Bit 7 is the most significant bit. The value of the a = alpha
-bits is undefined when reading from the driver, ignored when writing
-to the driver, except when alpha blending has been negotiated for a
-<link linkend="overlay">Video Overlay</link> or <link linkend="osd">
-Video Output Overlay</link> or when the alpha component has been configured
-for a <link linkend="capture">Video Capture</link> by means of <link
-linkend="v4l2-alpha-component"> <constant>V4L2_CID_ALPHA_COMPONENT
-</constant> </link> control.</para>
+ <para>Bit 7 is the most significant bit.</para>
+
+ <para>The usage and value of the alpha bits (a) in the ARGB and ABGR formats
+ (collectively referred to as alpha formats) depend on the device type and
+ hardware operation. <link linkend="capture">Capture</link> devices
+ (including capture queues of mem-to-mem devices) fill the alpha component in
+ memory. When the device outputs an alpha channel the alpha component will
+ have a meaningful value. Otherwise, when the device doesn't output an alpha
+ channel but can set the alpha bit to a user-configurable value, the <link
+ linkend="v4l2-alpha-component"><constant>V4L2_CID_ALPHA_COMPONENT</constant>
+ </link> control is used to specify that alpha value, and the alpha component
+ of all pixels will be set to the value specified by that control. Otherwise
+ a corresponding format without an alpha component (XRGB or XBGR) must be
+ used instead of an alpha format.</para>
+
+ <para><link linkend="output">Output</link> devices (including output queues
+ of mem-to-mem devices and <link linkend="osd">video output overlay</link>
+ devices) read the alpha component from memory. When the device processes the
+ alpha channel the alpha component must be filled with meaningful values by
+ applications. Otherwise a corresponding format without an alpha component
+ (XRGB or XBGR) must be used instead of an alpha format.</para>
+
+ <para>The XRGB and XBGR formats contain undefined bits (-). Applications,
+ devices and drivers must ignore those bits, for both <link
+ linkend="capture">capture</link> and <link linkend="output">output</link>
+ devices.</para>
<example>
<title><constant>V4L2_PIX_FMT_BGR24</constant> 4 × 4 pixel
</formalpara>
</example>
+ <para>Formats defined in <xref linkend="rgb-formats-deprecated"/> are
+ deprecated and must not be used by new drivers. They are documented here for
+ reference. The meaning of their alpha bits (a) is ill-defined and
+ interpreted as in either the corresponding ARGB or XRGB format, depending on
+ the driver.</para>
+
+ <table pgwide="1" frame="none" id="rgb-formats-deprecated">
+ <title>Deprecated Packed RGB Image Formats</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" />
+
+ <colspec colnum="13" colname="b17" align="center" />
+ <colspec colnum="14" colname="b16" align="center" />
+ <colspec colnum="15" colname="b15" align="center" />
+ <colspec colnum="16" colname="b14" align="center" />
+ <colspec colnum="17" colname="b13" align="center" />
+ <colspec colnum="18" colname="b12" align="center" />
+ <colspec colnum="19" colname="b11" align="center" />
+ <colspec colnum="20" colname="b10" align="center" />
+
+ <colspec colnum="22" colname="b27" align="center" />
+ <colspec colnum="23" colname="b26" align="center" />
+ <colspec colnum="24" colname="b25" align="center" />
+ <colspec colnum="25" colname="b24" align="center" />
+ <colspec colnum="26" colname="b23" align="center" />
+ <colspec colnum="27" colname="b22" align="center" />
+ <colspec colnum="28" colname="b21" align="center" />
+ <colspec colnum="29" colname="b20" align="center" />
+
+ <colspec colnum="31" colname="b37" align="center" />
+ <colspec colnum="32" colname="b36" align="center" />
+ <colspec colnum="33" colname="b35" align="center" />
+ <colspec colnum="34" colname="b34" align="center" />
+ <colspec colnum="35" colname="b33" align="center" />
+ <colspec colnum="36" colname="b32" align="center" />
+ <colspec colnum="37" colname="b31" align="center" />
+ <colspec colnum="38" colname="b30" 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> </entry>
+ <entry spanname="b0">Byte 0 in memory</entry>
+ <entry spanname="b1">Byte 1</entry>
+ <entry spanname="b2">Byte 2</entry>
+ <entry spanname="b3">Byte 3</entry>
+ </row>
+ <row>
+ <entry> </entry>
+ <entry> </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>
+ <entry> </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>
+ <entry> </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>
+ <entry> </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>
+ <row id="V4L2-PIX-FMT-RGB444">
+ <entry><constant>V4L2_PIX_FMT_RGB444</constant></entry>
+ <entry>'R444'</entry>
+ <entry></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>a<subscript>3</subscript></entry>
+ <entry>a<subscript>2</subscript></entry>
+ <entry>a<subscript>1</subscript></entry>
+ <entry>a<subscript>0</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-RGB555">
+ <entry><constant>V4L2_PIX_FMT_RGB555</constant></entry>
+ <entry>'RGBO'</entry>
+ <entry></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>a</entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-BGR32">
+ <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry>
+ <entry>'BGR4'</entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>a<subscript>7</subscript></entry>
+ <entry>a<subscript>6</subscript></entry>
+ <entry>a<subscript>5</subscript></entry>
+ <entry>a<subscript>4</subscript></entry>
+ <entry>a<subscript>3</subscript></entry>
+ <entry>a<subscript>2</subscript></entry>
+ <entry>a<subscript>1</subscript></entry>
+ <entry>a<subscript>0</subscript></entry>
+ </row>
+ <row id="V4L2-PIX-FMT-RGB32">
+ <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry>
+ <entry>'RGB4'</entry>
+ <entry></entry>
+ <entry>a<subscript>7</subscript></entry>
+ <entry>a<subscript>6</subscript></entry>
+ <entry>a<subscript>5</subscript></entry>
+ <entry>a<subscript>4</subscript></entry>
+ <entry>a<subscript>3</subscript></entry>
+ <entry>a<subscript>2</subscript></entry>
+ <entry>a<subscript>1</subscript></entry>
+ <entry>a<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>r<subscript>7</subscript></entry>
+ <entry>r<subscript>6</subscript></entry>
+ <entry>r<subscript>5</subscript></entry>
+ <entry>r<subscript>4</subscript></entry>
+ <entry>r<subscript>3</subscript></entry>
+ <entry>r<subscript>2</subscript></entry>
+ <entry>r<subscript>1</subscript></entry>
+ <entry>r<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>g<subscript>7</subscript></entry>
+ <entry>g<subscript>6</subscript></entry>
+ <entry>g<subscript>5</subscript></entry>
+ <entry>g<subscript>4</subscript></entry>
+ <entry>g<subscript>3</subscript></entry>
+ <entry>g<subscript>2</subscript></entry>
+ <entry>g<subscript>1</subscript></entry>
+ <entry>g<subscript>0</subscript></entry>
+ <entry></entry>
+ <entry>b<subscript>7</subscript></entry>
+ <entry>b<subscript>6</subscript></entry>
+ <entry>b<subscript>5</subscript></entry>
+ <entry>b<subscript>4</subscript></entry>
+ <entry>b<subscript>3</subscript></entry>
+ <entry>b<subscript>2</subscript></entry>
+ <entry>b<subscript>1</subscript></entry>
+ <entry>b<subscript>0</subscript></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
<para>A test utility to determine which RGB formats a driver
actually supports is available from the LinuxTV v4l-dvb repository.
See &v4l-dvb; for access instructions.</para>