<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>
+ <entry><para>This field indicates whether the remaining fields of the
+<structname>v4l2_pix_format</structname> structure, also called the extended
+fields, are valid. When set to <constant>V4L2_PIX_FMT_PRIV_MAGIC</constant>, it
+indicates that the extended fields have been correctly initialized. When set to
+any other value it indicates that the extended fields contain undefined values.
+</para>
+<para>Applications that wish to use the pixel format extended fields must first
+ensure that the feature is supported by querying the device for the
+<link linkend="querycap"><constant>V4L2_CAP_EXT_PIX_FORMAT</constant></link>
+capability. If the capability isn't set the pixel format extended fields are not
+supported and using the extended fields will lead to undefined results.</para>
+<para>To use the extended fields, applications must set the
+<structfield>priv</structfield> field to
+<constant>V4L2_PIX_FMT_PRIV_MAGIC</constant>, initialize all the extended fields
+and zero the unused bytes of the <structname>v4l2_format</structname>
+<structfield>raw_data</structfield> field.</para>
+<para>When the <structfield>priv</structfield> field isn't set to
+<constant>V4L2_PIX_FMT_PRIV_MAGIC</constant> drivers must act as if all the
+extended fields were set to zero. On return drivers must set the
+<structfield>priv</structfield> field to
+<constant>V4L2_PIX_FMT_PRIV_MAGIC</constant> and all the extended field to
+applicable values.</para></entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>flags</structfield></entry>
+ <entry>Flags set by the application or driver, see <xref
+linkend="format-flags" />.</entry>
</row>
</tbody>
</tgroup>
and the number of valid entries in the
<structfield>plane_fmt</structfield> array.</entry>
</row>
+ <row>
+ <entry>__u8</entry>
+ <entry><structfield>flags</structfield></entry>
+ <entry>Flags set by the application or driver, see <xref
+linkend="format-flags" />.</entry>
+ </row>
<row>
<entry>__u8</entry>
- <entry><structfield>reserved[11]</structfield></entry>
+ <entry><structfield>reserved[10]</structfield></entry>
<entry>Reserved for future extensions. Should be zeroed by the
application.</entry>
</row>
</tbody>
</tgroup>
</table>
+
+ <table frame="none" pgwide="1" id="format-flags">
+ <title>Format Flags</title>
+ <tgroup cols="3">
+ &cs-def;
+ <tbody valign="top">
+ <row>
+ <entry><constant>V4L2_PIX_FMT_FLAG_PREMUL_ALPHA</constant></entry>
+ <entry>0x00000001</entry>
+ <entry>The pixel values are premultiplied by the alpha channel value.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
</section>