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diff --git a/Documentation/media/uapi/v4l/ext-ctrls-jpeg.rst b/Documentation/media/uapi/v4l/ext-ctrls-jpeg.rst deleted file mode 100644 index 60ce3f949319..000000000000 --- a/Documentation/media/uapi/v4l/ext-ctrls-jpeg.rst +++ /dev/null @@ -1,113 +0,0 @@ -.. Permission is granted to copy, distribute and/or modify this -.. document under the terms of the GNU Free Documentation License, -.. Version 1.1 or any later version published by the Free Software -.. Foundation, with no Invariant Sections, no Front-Cover Texts -.. and no Back-Cover Texts. A copy of the license is included at -.. Documentation/media/uapi/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections - -.. _jpeg-controls: - -********************** -JPEG Control Reference -********************** - -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. - - -.. _jpeg-control-id: - -JPEG Control IDs -================ - -``V4L2_CID_JPEG_CLASS (class)`` - The JPEG class descriptor. Calling - :ref:`VIDIOC_QUERYCTRL` for this control will - return a description of this control class. - -``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)`` - 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 :ref:`itu-t81`, clause A.1.1. for more - details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines - how Cb and Cr components are downsampled after converting an input - image from RGB to Y'CbCr color space. - -.. tabularcolumns:: |p{7.5cm}|p{10.0cm}| - -.. flat-table:: - :header-rows: 0 - :stub-columns: 0 - - * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444`` - - No chroma subsampling, each pixel has Y, Cr and Cb values. - * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422`` - - Horizontally subsample Cr, Cb components by a factor of 2. - * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420`` - - Subsample Cr, Cb components horizontally and vertically by 2. - * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411`` - - Horizontally subsample Cr, Cb components by a factor of 4. - * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410`` - - Subsample Cr, Cb components horizontally by 4 and vertically by 2. - * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY`` - - Use only luminance component. - - - -``V4L2_CID_JPEG_RESTART_INTERVAL (integer)`` - 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 - ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm - markers will not be inserted. - -.. _jpeg-quality-control: - -``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)`` - ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` 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, - ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by - driver to 0. - - 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. - -.. _jpeg-active-marker-control: - -``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)`` - Specify which JPEG markers are included in compressed stream. This - control is valid only for encoders. - - - -.. flat-table:: - :header-rows: 0 - :stub-columns: 0 - - * - ``V4L2_JPEG_ACTIVE_MARKER_APP0`` - - Application data segment APP\ :sub:`0`. - * - ``V4L2_JPEG_ACTIVE_MARKER_APP1`` - - Application data segment APP\ :sub:`1`. - * - ``V4L2_JPEG_ACTIVE_MARKER_COM`` - - Comment segment. - * - ``V4L2_JPEG_ACTIVE_MARKER_DQT`` - - Quantization tables segment. - * - ``V4L2_JPEG_ACTIVE_MARKER_DHT`` - - Huffman tables segment. - - - -For more details about JPEG specification, refer to :ref:`itu-t81`, -:ref:`jfif`, :ref:`w3c-jpeg-jfif`. |