summaryrefslogtreecommitdiff
path: root/Documentation/DocBook/media/v4l/controls.xml
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/DocBook/media/v4l/controls.xml')
-rw-r--r--Documentation/DocBook/media/v4l/controls.xml220
1 files changed, 220 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index a1be37897ad7..b84f25e9cc87 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -1286,6 +1286,49 @@ produce a slight hiss, but in the encoder itself, guaranteeing a fixed
and reproducible audio bitstream. 0 = unmuted, 1 = muted.</entry>
</row>
<row><entry></entry></row>
+ <row id="v4l2-mpeg-audio-dec-playback">
+ <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK</constant>&nbsp;</entry>
+ <entry>enum&nbsp;v4l2_mpeg_audio_dec_playback</entry>
+ </row><row><entry spanname="descr">Determines how monolingual audio should be played back.
+Possible values are:</entry>
+ </row>
+ <row>
+ <entrytbl spanname="descr" cols="2">
+ <tbody valign="top">
+ <row>
+ <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO</constant>&nbsp;</entry>
+ <entry>Automatically determines the best playback mode.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO</constant>&nbsp;</entry>
+ <entry>Stereo playback.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT</constant>&nbsp;</entry>
+ <entry>Left channel playback.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT</constant>&nbsp;</entry>
+ <entry>Right channel playback.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO</constant>&nbsp;</entry>
+ <entry>Mono playback.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO</constant>&nbsp;</entry>
+ <entry>Stereo playback with swapped left and right channels.</entry>
+ </row>
+ </tbody>
+ </entrytbl>
+ </row>
+ <row><entry></entry></row>
+ <row id="v4l2-mpeg-audio-dec-multilingual-playback">
+ <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK</constant>&nbsp;</entry>
+ <entry>enum&nbsp;v4l2_mpeg_audio_dec_playback</entry>
+ </row><row><entry spanname="descr">Determines how multilingual audio should be played back.</entry>
+ </row>
+ <row><entry></entry></row>
<row id="v4l2-mpeg-video-encoding">
<entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ENCODING</constant>&nbsp;</entry>
<entry>enum&nbsp;v4l2_mpeg_video_encoding</entry>
@@ -1447,6 +1490,22 @@ of the video. The supplied 32-bit integer is interpreted as follows (bit
</tbody>
</entrytbl>
</row>
+ <row><entry></entry></row>
+ <row id="v4l2-mpeg-video-dec-pts">
+ <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_DEC_PTS</constant>&nbsp;</entry>
+ <entry>integer64</entry>
+ </row><row><entry spanname="descr">This read-only control returns the
+33-bit video Presentation Time Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of
+the currently displayed frame. This is the same PTS as is used in &VIDIOC-DECODER-CMD;.</entry>
+ </row>
+ <row><entry></entry></row>
+ <row id="v4l2-mpeg-video-dec-frame">
+ <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_DEC_FRAME</constant>&nbsp;</entry>
+ <entry>integer64</entry>
+ </row><row><entry spanname="descr">This read-only control returns the
+frame counter of the frame that is currently displayed (decoded). This value is reset to 0 whenever
+the decoder is started.</entry>
+ </row>
<row><entry></entry></row>
@@ -3377,6 +3436,167 @@ 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>&nbsp;</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>