Add DocBook entries for the JPEG control class. Signed-off-by: Sylwester Nawrocki <snjw23@xxxxxxxxx> --- Documentation/DocBook/media/v4l/biblio.xml | 20 +++ Documentation/DocBook/media/v4l/controls.xml | 161 ++++++++++++++++++++ .../DocBook/media/v4l/vidioc-g-jpegcomp.xml | 16 ++- 3 files changed, 195 insertions(+), 2 deletions(-) diff --git a/Documentation/DocBook/media/v4l/biblio.xml b/Documentation/DocBook/media/v4l/biblio.xml index cea6fd3..7dc65c5 100644 --- a/Documentation/DocBook/media/v4l/biblio.xml +++ b/Documentation/DocBook/media/v4l/biblio.xml @@ -128,6 +128,26 @@ url="http://www.ijg.org";>http://www.ijg.org</ulink>)</corpauthor> <subtitle>Version 1.02</subtitle> </biblioentry> + <biblioentry id="itu-t81"> + <abbrev>ITU-T.81</abbrev> + <authorgroup> + <corpauthor>International Telecommunication Union +(<ulink url="http://www.itu.int";>http://www.itu.int</ulink>)</corpauthor> + </authorgroup> + <title>ITU-T Recommendation T.81 +"Information Technology — Digital Compression and Coding of Continous-Tone +Still Images — Requirements and Guidelines"</title> + </biblioentry> + + <biblioentry id="w3c-jpeg-jfif"> + <abbrev>W3C JPEG JFIF</abbrev> + <authorgroup> + <corpauthor>The World Wide Web Consortium (<ulink +url="http://www.w3.org/Graphics/JPEG";>http://www.w3.org</ulink>)</corpauthor> + </authorgroup> + <title>JPEG JFIF</title> + </biblioentry> + <biblioentry id="smpte12m"> <abbrev>SMPTE 12M</abbrev> <authorgroup> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml index c0422c6..ab9e56b 100644 --- a/Documentation/DocBook/media/v4l/controls.xml +++ b/Documentation/DocBook/media/v4l/controls.xml @@ -3364,6 +3364,167 @@ interface and may change in the future.</para> </tbody> </tgroup> </table> + </section> + + <section id="jpeg-controls"> + <title>JPEG Control Reference</title> + <para>The JPEG class includes controls for common features of JPEG + encoders and decoders. Currently it includes features for codecs + implementing progressive baseline DCT compression process with + Huffman entrophy coding.</para> + <table pgwide="1" frame="none" id="jpeg-control-id"> + <title>JPEG Control IDs</title> + <tgroup cols="4"> + <colspec colname="c1" colwidth="1*" /> + <colspec colname="c2" colwidth="6*" /> + <colspec colname="c3" colwidth="2*" /> + <colspec colname="c4" colwidth="6*" /> + <spanspec namest="c1" nameend="c2" spanname="id" /> + <spanspec namest="c2" nameend="c4" spanname="descr" /> + <thead> + <row> + <entry spanname="id" align="left">ID</entry> + <entry align="left">Type</entry> + </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry> + </row> + </thead> + <tbody valign="top"> + <row><entry></entry></row> + <row> + <entry spanname="id"><constant>V4L2_CID_JPEG_CLASS</constant> </entry> + <entry>class</entry> + </row><row><entry spanname="descr">The JPEG class descriptor. Calling + &VIDIOC-QUERYCTRL; for this control will return a description of this + control class. + + </entry> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_JPEG_CHROMA_SUBSAMPLING</constant></entry> + <entry>menu</entry> + </row> + <row id="jpeg-chroma-subsampling-control"> + <entry spanname="descr">The chroma subsampling factors describe how + each component of an input image is sampled, in respect to maximum + sample rate in each spatial dimension. See <xref linkend="itu-t81"/>, + clause A.1.1. for more details. The <constant> + V4L2_CID_JPEG_CHROMA_SUBSAMPLING</constant> control determines how + Cb and Cr components are downsampled after coverting an input image + from RGB to Y'CbCr color space. + </entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_JPEG_CHROMA_SUBSAMPLING_444</constant> + </entry><entry>No chroma subsampling, each pixel has + Y, Cr and Cb values.</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_CHROMA_SUBSAMPLING_422</constant> + </entry><entry>Horizontally subsample Cr, Cb components + by a factor of 2.</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_CHROMA_SUBSAMPLING_420</constant> + </entry><entry>Subsample Cr, Cb components horizontally + and vertically by 2.</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_CHROMA_SUBSAMPLING_411</constant> + </entry><entry>Horizontally subsample Cr, Cb components + by a factor of 4.</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_CHROMA_SUBSAMPLING_410</constant> + </entry><entry>Subsample Cr, Cb components horizontally + by 4 and vertically by 2.</entry> + </row> + <row> + <entry><constant>V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY</constant> + </entry><entry>Use only luminance component.</entry> + </row> + </tbody> + </entrytbl> + </row> + <row> + <entry spanname="id"><constant>V4L2_CID_JPEG_RESTART_INTERVAL</constant> + </entry><entry>integer</entry> + </row> + <row><entry spanname="descr"> + The restart interval determines an interval of inserting RSTm + markers (m = 0..7). The purpose of these markers is to additionally + reinitialize the encoder process, in order to process blocks of + an image independently. + For the lossy compression processes the restart interval unit is + MCU (Minimum Coded Unit) and its value is contained in DRI + (Define Restart Interval) marker. If <constant> + V4L2_CID_JPEG_RESTART_INTERVAL</constant> control is set to 0, + DRI and RSTm markers will not be inserted. + </entry> + </row> + <row id="jpeg-quality-control"> + <entry spanname="id"><constant>V4L2_CID_JPEG_COMPRESION_QUALITY</constant></entry> + <entry>integer</entry> + </row> + <row> + <entry spanname="descr"> + <constant>V4L2_CID_JPEG_COMPRESION_QUALITY</constant> control + determines trade-off between image quality and size. + It provides simpler method for applications to control image quality, + without a need for direct reconfiguration of luminance and chrominance + quantization tables. + + In cases where a driver uses quantization tables configured directly + by an application, using interfaces defined elsewhere, <constant> + V4L2_CID_JPEG_COMPRESION_QUALITY</constant> control should be set + by driver to 0. + + <para>The value range of this control is driver-specific. Only + positive, non-zero values are meaningful. The recommended range + is 1 - 100, where larger values correspond to better image quality. + </para> + </entry> + </row> + <row id="jpeg-active-marker-control"> + <entry spanname="id"><constant>V4L2_CID_JPEG_ACTIVE_MARKER</constant></entry> + <entry>bitmask</entry> + </row> + <row> + <entry spanname="descr">Specify which JPEG markers are included + in compressed stream. This control is valid only for encoders. + </entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_JPEG_ACTIVE_MARKER_APP0</constant></entry> + <entry>Application data segment APP<subscript>0</subscript>.</entry> + </row><row> + <entry><constant>V4L2_JPEG_ACTIVE_MARKER_APP1</constant></entry> + <entry>Application data segment APP<subscript>1</subscript>.</entry> + </row><row> + <entry><constant>V4L2_JPEG_ACTIVE_MARKER_COM</constant></entry> + <entry>Comment segment.</entry> + </row><row> + <entry><constant>V4L2_JPEG_ACTIVE_MARKER_DQT</constant></entry> + <entry>Quantization tables segment.</entry> + </row><row> + <entry><constant>V4L2_JPEG_ACTIVE_MARKER_DHT</constant></entry> + <entry>Huffman tables segment.</entry> + </row> + </tbody> + </entrytbl> + </row> + <row><entry></entry></row> + </tbody> + </tgroup> + </table> + <para>For more details about JPEG specification, refer + to <xref linkend="itu-t81"/>, <xref linkend="jfif"/>, + <xref linkend="w3c-jpeg-jfif"/>.</para> </section> </section> diff --git a/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml b/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml index 01ea24b..4874849 100644 --- a/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml +++ b/Documentation/DocBook/media/v4l/vidioc-g-jpegcomp.xml @@ -57,6 +57,11 @@ <refsect1> <title>Description</title> + <para>These ioctls are <emphasis role="bold">deprecated</emphasis>. + New drivers and applications should use <link linkend="jpeg-controls"> + JPEG class controls</link> for image quality and JPEG markers control. + </para> + <para>[to do]</para> <para>Ronald Bultje elaborates:</para> @@ -86,7 +91,10 @@ to add them.</para> <row> <entry>int</entry> <entry><structfield>quality</structfield></entry> - <entry></entry> + <entry>Deprecated. If <link linkend="jpeg-quality-control"><constant> + V4L2_CID_JPEG_IMAGE_QUALITY</constant></link> control is exposed by + a driver applications should use it instead and ignore this field. + </entry> </row> <row> <entry>int</entry> @@ -116,7 +124,11 @@ to add them.</para> <row> <entry>__u32</entry> <entry><structfield>jpeg_markers</structfield></entry> - <entry>See <xref linkend="jpeg-markers" />.</entry> + <entry>See <xref linkend="jpeg-markers"/>. Deprecated. + If <link linkend="jpeg-active-marker-control"><constant> + V4L2_CID_JPEG_ACTIVE_MARKER</constant></link> control + is exposed by a driver applications should use it instead + and ignore this field.</entry> </row> </tbody> </tgroup> -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
