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Diffstat (limited to 'Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst | 97 |
1 files changed, 83 insertions, 14 deletions
diff --git a/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst b/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst index 759420a872d6..9c423ffe02f9 100644 --- a/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst +++ b/Documentation/userspace-api/media/v4l/pixfmt-v4l2.rst @@ -1,17 +1,10 @@ -.. 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/userspace-api/media/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later ****************************** Single-planar format structure ****************************** -.. tabularcolumns:: |p{4.0cm}|p{2.5cm}|p{11.0cm}| +.. tabularcolumns:: |p{4.0cm}|p{2.6cm}|p{10.7cm}| .. c:type:: v4l2_pix_format @@ -44,6 +37,11 @@ Single-planar format structure inside the stream, when fed to a stateful mem2mem decoder, the fields may be zero to rely on the decoder to detect the right values. For more details see :ref:`decoder` and format descriptions. + + For compressed formats on the CAPTURE side of a stateful mem2mem + encoder, the fields must be zero, since the coded size is expected to + be calculated internally by the encoder itself, based on the OUTPUT + side. For more details see :ref:`encoder` and format descriptions. * - __u32 - ``pixelformat`` - The pixel format or type of compression, set by the application. @@ -111,7 +109,14 @@ Single-planar format structure - Image colorspace, from enum :c:type:`v4l2_colorspace`. This information supplements the ``pixelformat`` and must be set by the driver for capture streams and by the application for - output streams, see :ref:`colorspaces`. + output streams, see :ref:`colorspaces`. If the application sets the + flag ``V4L2_PIX_FMT_FLAG_SET_CSC`` then the application can set + this field for a capture stream to request a specific colorspace + for the captured image data. If the driver cannot handle requested + conversion, it will return another supported colorspace. + The driver indicates that colorspace conversion is supported by setting + the flag V4L2_FMT_FLAG_CSC_COLORSPACE in the corresponding struct + :c:type:`v4l2_fmtdesc` during enumeration. See :ref:`fmtdesc-flags`. * - __u32 - ``priv`` - This field indicates whether the remaining fields of the @@ -148,13 +153,29 @@ Single-planar format structure - Y'CbCr encoding, from enum :c:type:`v4l2_ycbcr_encoding`. This information supplements the ``colorspace`` and must be set by the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. + streams, see :ref:`colorspaces`. If the application sets the + flag ``V4L2_PIX_FMT_FLAG_SET_CSC`` then the application can set + this field for a capture stream to request a specific Y'CbCr encoding + for the captured image data. If the driver cannot handle requested + conversion, it will return another supported encoding. + This field is ignored for HSV pixelformats. The driver indicates that + ycbcr_enc conversion is supported by setting the flag + V4L2_FMT_FLAG_CSC_YCBCR_ENC in the corresponding struct + :c:type:`v4l2_fmtdesc` during enumeration. See :ref:`fmtdesc-flags`. * - __u32 - ``hsv_enc`` - HSV encoding, from enum :c:type:`v4l2_hsv_encoding`. This information supplements the ``colorspace`` and must be set by the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. + streams, see :ref:`colorspaces`. If the application sets the flag + ``V4L2_PIX_FMT_FLAG_SET_CSC`` then the application can set this + field for a capture stream to request a specific HSV encoding for the + captured image data. If the driver cannot handle requested + conversion, it will return another supported encoding. + This field is ignored for non-HSV pixelformats. The driver indicates + that hsv_enc conversion is supported by setting the flag + V4L2_FMT_FLAG_CSC_HSV_ENC in the corresponding struct + :c:type:`v4l2_fmtdesc` during enumeration. See :ref:`fmtdesc-flags`. * - } - * - __u32 @@ -162,10 +183,58 @@ Single-planar format structure - Quantization range, from enum :c:type:`v4l2_quantization`. This information supplements the ``colorspace`` and must be set by the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. + streams, see :ref:`colorspaces`. If the application sets the flag + ``V4L2_PIX_FMT_FLAG_SET_CSC`` then the application can set + this field for a capture stream to request a specific quantization + range for the captured image data. If the driver cannot handle requested + conversion, it will return another supported quantization. + The driver indicates that quantization conversion is supported by setting + the flag V4L2_FMT_FLAG_CSC_QUANTIZATION in the corresponding struct + :c:type:`v4l2_fmtdesc` during enumeration. See :ref:`fmtdesc-flags`. * - __u32 - ``xfer_func`` - Transfer function, from enum :c:type:`v4l2_xfer_func`. This information supplements the ``colorspace`` and must be set by the driver for capture streams and by the application for output - streams, see :ref:`colorspaces`. + streams, see :ref:`colorspaces`. If the application sets the flag + ``V4L2_PIX_FMT_FLAG_SET_CSC`` then the application can set + this field for a capture stream to request a specific transfer function + for the captured image data. If the driver cannot handle requested + conversion, it will return another supported transfer function. + The driver indicates that xfer_func conversion is supported by setting + the flag V4L2_FMT_FLAG_CSC_XFER_FUNC in the corresponding struct + :c:type:`v4l2_fmtdesc` during enumeration. See :ref:`fmtdesc-flags`. + +.. tabularcolumns:: |p{6.8cm}|p{2.3cm}|p{8.2cm}| + +.. _format-flags: + +.. flat-table:: Format Flags + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + * - ``V4L2_PIX_FMT_FLAG_PREMUL_ALPHA`` + - 0x00000001 + - The color values are premultiplied by the alpha channel value. For + example, if a light blue pixel with 50% transparency was described + by RGBA values (128, 192, 255, 128), the same pixel described with + premultiplied colors would be described by RGBA values (64, 96, + 128, 128) + * .. _`v4l2-pix-fmt-flag-set-csc`: + + - ``V4L2_PIX_FMT_FLAG_SET_CSC`` + - 0x00000002 + - Set by the application. It is only used for capture and is + ignored for output streams. If set, then request the device to do + colorspace conversion from the received colorspace to the requested + colorspace values. If the colorimetry field (``colorspace``, ``xfer_func``, + ``ycbcr_enc``, ``hsv_enc`` or ``quantization``) is set to ``*_DEFAULT``, + then that colorimetry setting will remain unchanged from what was received. + So in order to change the quantization, only the ``quantization`` field shall + be set to non default value (``V4L2_QUANTIZATION_FULL_RANGE`` or + ``V4L2_QUANTIZATION_LIM_RANGE``) and all other colorimetry fields shall + be set to ``*_DEFAULT``. + + To check which conversions are supported by the hardware for the current + pixel format, see :ref:`fmtdesc-flags`. |