1.. Permission is granted to copy, distribute and/or modify this 2.. document under the terms of the GNU Free Documentation License, 3.. Version 1.1 or any later version published by the Free Software 4.. Foundation, with no Invariant Sections, no Front-Cover Texts 5.. and no Back-Cover Texts. A copy of the license is included at 6.. Documentation/userspace-api/media/fdl-appendix.rst. 7.. 8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections 9 10****************************** 11Single-planar format structure 12****************************** 13 14.. tabularcolumns:: |p{4.0cm}|p{2.5cm}|p{11.0cm}| 15 16.. c:type:: v4l2_pix_format 17 18.. cssclass:: longtable 19 20.. flat-table:: struct v4l2_pix_format 21 :header-rows: 0 22 :stub-columns: 0 23 :widths: 1 1 2 24 25 * - __u32 26 - ``width`` 27 - Image width in pixels. 28 * - __u32 29 - ``height`` 30 - Image height in pixels. If ``field`` is one of ``V4L2_FIELD_TOP``, 31 ``V4L2_FIELD_BOTTOM`` or ``V4L2_FIELD_ALTERNATE`` then height 32 refers to the number of lines in the field, otherwise it refers to 33 the number of lines in the frame (which is twice the field height 34 for interlaced formats). 35 * - :cspan:`2` Applications set these fields to request an image 36 size, drivers return the closest possible values. In case of 37 planar formats the ``width`` and ``height`` applies to the largest 38 plane. To avoid ambiguities drivers must return values rounded up 39 to a multiple of the scale factor of any smaller planes. For 40 example when the image format is YUV 4:2:0, ``width`` and 41 ``height`` must be multiples of two. 42 43 For compressed formats that contain the resolution information encoded 44 inside the stream, when fed to a stateful mem2mem decoder, the fields 45 may be zero to rely on the decoder to detect the right values. For more 46 details see :ref:`decoder` and format descriptions. 47 * - __u32 48 - ``pixelformat`` 49 - The pixel format or type of compression, set by the application. 50 This is a little endian 51 :ref:`four character code <v4l2-fourcc>`. V4L2 defines standard 52 RGB formats in :ref:`pixfmt-rgb`, YUV formats in 53 :ref:`yuv-formats`, and reserved codes in 54 :ref:`reserved-formats` 55 * - __u32 56 - ``field`` 57 - Field order, from enum :c:type:`v4l2_field`. 58 Video images are typically interlaced. Applications can request to 59 capture or output only the top or bottom field, or both fields 60 interlaced or sequentially stored in one buffer or alternating in 61 separate buffers. Drivers return the actual field order selected. 62 For more details on fields see :ref:`field-order`. 63 * - __u32 64 - ``bytesperline`` 65 - Distance in bytes between the leftmost pixels in two adjacent 66 lines. 67 * - :cspan:`2` 68 69 Both applications and drivers can set this field to request 70 padding bytes at the end of each line. Drivers however may ignore 71 the value requested by the application, returning ``width`` times 72 bytes per pixel or a larger value required by the hardware. That 73 implies applications can just set this field to zero to get a 74 reasonable default. 75 76 Video hardware may access padding bytes, therefore they must 77 reside in accessible memory. Consider cases where padding bytes 78 after the last line of an image cross a system page boundary. 79 Input devices may write padding bytes, the value is undefined. 80 Output devices ignore the contents of padding bytes. 81 82 When the image format is planar the ``bytesperline`` value applies 83 to the first plane and is divided by the same factor as the 84 ``width`` field for the other planes. For example the Cb and Cr 85 planes of a YUV 4:2:0 image have half as many padding bytes 86 following each line as the Y plane. To avoid ambiguities drivers 87 must return a ``bytesperline`` value rounded up to a multiple of 88 the scale factor. 89 90 For compressed formats the ``bytesperline`` value makes no sense. 91 Applications and drivers must set this to 0 in that case. 92 * - __u32 93 - ``sizeimage`` 94 - Size in bytes of the buffer to hold a complete image, set by the 95 driver. Usually this is ``bytesperline`` times ``height``. When 96 the image consists of variable length compressed data this is the 97 number of bytes required by the codec to support the worst-case 98 compression scenario. 99 100 The driver will set the value for uncompressed images. 101 102 Clients are allowed to set the sizeimage field for variable length 103 compressed data flagged with ``V4L2_FMT_FLAG_COMPRESSED`` at 104 :ref:`VIDIOC_ENUM_FMT`, but the driver may ignore it and set the 105 value itself, or it may modify the provided value based on 106 alignment requirements or minimum/maximum size requirements. 107 If the client wants to leave this to the driver, then it should 108 set sizeimage to 0. 109 * - __u32 110 - ``colorspace`` 111 - Image colorspace, from enum :c:type:`v4l2_colorspace`. 112 This information supplements the ``pixelformat`` and must be set 113 by the driver for capture streams and by the application for 114 output streams, see :ref:`colorspaces`. 115 * - __u32 116 - ``priv`` 117 - This field indicates whether the remaining fields of the 118 struct :c:type:`v4l2_pix_format`, also called the 119 extended fields, are valid. When set to 120 ``V4L2_PIX_FMT_PRIV_MAGIC``, it indicates that the extended fields 121 have been correctly initialized. When set to any other value it 122 indicates that the extended fields contain undefined values. 123 124 Applications that wish to use the pixel format extended fields 125 must first ensure that the feature is supported by querying the 126 device for the :ref:`V4L2_CAP_EXT_PIX_FORMAT <querycap>` 127 capability. If the capability isn't set the pixel format extended 128 fields are not supported and using the extended fields will lead 129 to undefined results. 130 131 To use the extended fields, applications must set the ``priv`` 132 field to ``V4L2_PIX_FMT_PRIV_MAGIC``, initialize all the extended 133 fields and zero the unused bytes of the 134 struct :c:type:`v4l2_format` ``raw_data`` field. 135 136 When the ``priv`` field isn't set to ``V4L2_PIX_FMT_PRIV_MAGIC`` 137 drivers must act as if all the extended fields were set to zero. 138 On return drivers must set the ``priv`` field to 139 ``V4L2_PIX_FMT_PRIV_MAGIC`` and all the extended fields to 140 applicable values. 141 * - __u32 142 - ``flags`` 143 - Flags set by the application or driver, see :ref:`format-flags`. 144 * - union { 145 - (anonymous) 146 * - __u32 147 - ``ycbcr_enc`` 148 - Y'CbCr encoding, from enum :c:type:`v4l2_ycbcr_encoding`. 149 This information supplements the ``colorspace`` and must be set by 150 the driver for capture streams and by the application for output 151 streams, see :ref:`colorspaces`. 152 * - __u32 153 - ``hsv_enc`` 154 - HSV encoding, from enum :c:type:`v4l2_hsv_encoding`. 155 This information supplements the ``colorspace`` and must be set by 156 the driver for capture streams and by the application for output 157 streams, see :ref:`colorspaces`. 158 * - } 159 - 160 * - __u32 161 - ``quantization`` 162 - Quantization range, from enum :c:type:`v4l2_quantization`. 163 This information supplements the ``colorspace`` and must be set by 164 the driver for capture streams and by the application for output 165 streams, see :ref:`colorspaces`. 166 * - __u32 167 - ``xfer_func`` 168 - Transfer function, from enum :c:type:`v4l2_xfer_func`. 169 This information supplements the ``colorspace`` and must be set by 170 the driver for capture streams and by the application for output 171 streams, see :ref:`colorspaces`. 172