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Diffstat (limited to 'Documentation/DocBook/media/v4l/controls.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/controls.xml | 220 |
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> </entry> + <entry>enum 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> </entry> + <entry>Automatically determines the best playback mode.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO</constant> </entry> + <entry>Stereo playback.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT</constant> </entry> + <entry>Left channel playback.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT</constant> </entry> + <entry>Right channel playback.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO</constant> </entry> + <entry>Mono playback.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO</constant> </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> </entry> + <entry>enum 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> </entry> <entry>enum 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> </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> </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> </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> |