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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _VIDIOC_ENUM_FMT:5 6*********************7ioctl VIDIOC_ENUM_FMT8*********************9 10Name11====12 13VIDIOC_ENUM_FMT - Enumerate image formats14 15Synopsis16========17 18.. c:macro:: VIDIOC_ENUM_FMT19 20``int ioctl(int fd, VIDIOC_ENUM_FMT, struct v4l2_fmtdesc *argp)``21 22Arguments23=========24 25``fd``26 File descriptor returned by :c:func:`open()`.27 28``argp``29 Pointer to struct :c:type:`v4l2_fmtdesc`.30 31Description32===========33 34To enumerate image formats applications initialize the ``type``, ``mbus_code``35and ``index`` fields of struct :c:type:`v4l2_fmtdesc` and call36the :ref:`VIDIOC_ENUM_FMT` ioctl with a pointer to this structure. Drivers37fill the rest of the structure or return an ``EINVAL`` error code. All38formats are enumerable by beginning at index zero and incrementing by39one until ``EINVAL`` is returned. If applicable, drivers shall return40formats in preference order, where preferred formats are returned before41(that is, with lower ``index`` value) less-preferred formats.42 43Depending on the ``V4L2_CAP_IO_MC`` :ref:`capability <device-capabilities>`,44the ``mbus_code`` field is handled differently:45 461) ``V4L2_CAP_IO_MC`` is not set (also known as a 'video-node-centric' driver)47 48 Applications shall initialize the ``mbus_code`` field to zero and drivers49 shall ignore the value of the field.50 51 Drivers shall enumerate all image formats.52 53 .. note::54 55 After switching the input or output the list of enumerated image56 formats may be different.57 582) ``V4L2_CAP_IO_MC`` is set (also known as an 'MC-centric' driver)59 60 If the ``mbus_code`` field is zero, then all image formats61 shall be enumerated.62 63 If the ``mbus_code`` field is initialized to a valid (non-zero)64 :ref:`media bus format code <v4l2-mbus-pixelcode>`, then drivers65 shall restrict enumeration to only the image formats that can produce66 (for video output devices) or be produced from (for video capture67 devices) that media bus code. If the ``mbus_code`` is unsupported by68 the driver, then ``EINVAL`` shall be returned.69 70 Regardless of the value of the ``mbus_code`` field, the enumerated image71 formats shall not depend on the active configuration of the video device72 or device pipeline.73 74.. c:type:: v4l2_fmtdesc75 76.. cssclass:: longtable77 78.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|79 80.. flat-table:: struct v4l2_fmtdesc81 :header-rows: 082 :stub-columns: 083 :widths: 1 1 284 85 * - __u3286 - ``index``87 - Number of the format in the enumeration, set by the application.88 This is in no way related to the ``pixelformat`` field.89 * - __u3290 - ``type``91 - Type of the data stream, set by the application. Only these types92 are valid here: ``V4L2_BUF_TYPE_VIDEO_CAPTURE``,93 ``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``,94 ``V4L2_BUF_TYPE_VIDEO_OUTPUT``,95 ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE``,96 ``V4L2_BUF_TYPE_VIDEO_OVERLAY``,97 ``V4L2_BUF_TYPE_SDR_CAPTURE``,98 ``V4L2_BUF_TYPE_SDR_OUTPUT``,99 ``V4L2_BUF_TYPE_META_CAPTURE`` and100 ``V4L2_BUF_TYPE_META_OUTPUT``.101 See :c:type:`v4l2_buf_type`.102 * - __u32103 - ``flags``104 - See :ref:`fmtdesc-flags`105 * - __u8106 - ``description``\ [32]107 - Description of the format, a NUL-terminated ASCII string. This108 information is intended for the user, for example: "YUV 4:2:2".109 * - __u32110 - ``pixelformat``111 - The image format identifier. This is a four character code as112 computed by the v4l2_fourcc() macro:113 * - :cspan:`2`114 115 .. _v4l2-fourcc:116 117 ``#define v4l2_fourcc(a,b,c,d)``118 119 ``(((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24))``120 121 Several image formats are already defined by this specification in122 :ref:`pixfmt`.123 124 .. attention::125 126 These codes are not the same as those used127 in the Windows world.128 * - __u32129 - ``mbus_code``130 - Media bus code restricting the enumerated formats, set by the131 application. Only applicable to drivers that advertise the132 ``V4L2_CAP_IO_MC`` :ref:`capability <device-capabilities>`, shall be 0133 otherwise.134 * - __u32135 - ``reserved``\ [3]136 - Reserved for future extensions. Drivers must set the array to137 zero.138 139 140.. tabularcolumns:: |p{8.4cm}|p{1.8cm}|p{7.1cm}|141 142.. cssclass:: longtable143 144.. _fmtdesc-flags:145 146.. flat-table:: Image Format Description Flags147 :header-rows: 0148 :stub-columns: 0149 :widths: 3 1 4150 151 * - ``V4L2_FMT_FLAG_COMPRESSED``152 - 0x0001153 - This is a compressed format.154 * - ``V4L2_FMT_FLAG_EMULATED``155 - 0x0002156 - This format is not native to the device but emulated through157 software (usually libv4l2), where possible try to use a native158 format instead for better performance.159 * - ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM``160 - 0x0004161 - The hardware decoder for this compressed bytestream format (aka coded162 format) is capable of parsing a continuous bytestream. Applications do163 not need to parse the bytestream themselves to find the boundaries164 between frames/fields.165 166 This flag can only be used in combination with the167 ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to compressed168 formats only. This flag is valid for stateful decoders only.169 * - ``V4L2_FMT_FLAG_DYN_RESOLUTION``170 - 0x0008171 - Dynamic resolution switching is supported by the device for this172 compressed bytestream format (aka coded format). It will notify the user173 via the event ``V4L2_EVENT_SOURCE_CHANGE`` when changes in the video174 parameters are detected.175 176 This flag can only be used in combination with the177 ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to178 compressed formats only. This flag is valid for stateful codecs only.179 * - ``V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL``180 - 0x0010181 - The hardware encoder supports setting the ``CAPTURE`` coded frame182 interval separately from the ``OUTPUT`` raw frame interval.183 Setting the ``OUTPUT`` raw frame interval with :ref:`VIDIOC_S_PARM <VIDIOC_G_PARM>`184 also sets the ``CAPTURE`` coded frame interval to the same value.185 If this flag is set, then the ``CAPTURE`` coded frame interval can be186 set to a different value afterwards. This is typically used for187 offline encoding where the ``OUTPUT`` raw frame interval is used as188 a hint for reserving hardware encoder resources and the ``CAPTURE`` coded189 frame interval is the actual frame rate embedded in the encoded video190 stream.191 192 This flag can only be used in combination with the193 ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to194 compressed formats only. This flag is valid for stateful encoders only.195 * - ``V4L2_FMT_FLAG_CSC_COLORSPACE``196 - 0x0020197 - The driver allows the application to try to change the default198 colorspace. This flag is relevant only for capture devices.199 The application can ask to configure the colorspace of the capture device200 when calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with201 :ref:`V4L2_PIX_FMT_FLAG_SET_CSC <v4l2-pix-fmt-flag-set-csc>` set.202 * - ``V4L2_FMT_FLAG_CSC_XFER_FUNC``203 - 0x0040204 - The driver allows the application to try to change the default205 transfer function. This flag is relevant only for capture devices.206 The application can ask to configure the transfer function of the capture207 device when calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with208 :ref:`V4L2_PIX_FMT_FLAG_SET_CSC <v4l2-pix-fmt-flag-set-csc>` set.209 * - ``V4L2_FMT_FLAG_CSC_YCBCR_ENC``210 - 0x0080211 - The driver allows the application to try to change the default212 Y'CbCr encoding. This flag is relevant only for capture devices.213 The application can ask to configure the Y'CbCr encoding of the capture device214 when calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with215 :ref:`V4L2_PIX_FMT_FLAG_SET_CSC <v4l2-pix-fmt-flag-set-csc>` set.216 * - ``V4L2_FMT_FLAG_CSC_HSV_ENC``217 - 0x0080218 - The driver allows the application to try to change the default219 HSV encoding. This flag is relevant only for capture devices.220 The application can ask to configure the HSV encoding of the capture device221 when calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with222 :ref:`V4L2_PIX_FMT_FLAG_SET_CSC <v4l2-pix-fmt-flag-set-csc>` set.223 * - ``V4L2_FMT_FLAG_CSC_QUANTIZATION``224 - 0x0100225 - The driver allows the application to try to change the default226 quantization. This flag is relevant only for capture devices.227 The application can ask to configure the quantization of the capture228 device when calling the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl with229 :ref:`V4L2_PIX_FMT_FLAG_SET_CSC <v4l2-pix-fmt-flag-set-csc>` set.230 * - ``V4L2_FMT_FLAG_META_LINE_BASED``231 - 0x0200232 - The metadata format is line-based. In this case the ``width``,233 ``height`` and ``bytesperline`` fields of :c:type:`v4l2_meta_format` are234 valid. The buffer consists of ``height`` lines, each having ``width``235 Data Units of data and the offset (in bytes) between the beginning of236 each two consecutive lines is ``bytesperline``.237 238Return Value239============240 241On success 0 is returned, on error -1 and the ``errno`` variable is set242appropriately. The generic error codes are described at the243:ref:`Generic Error Codes <gen-errors>` chapter.244 245EINVAL246 The struct :c:type:`v4l2_fmtdesc` ``type`` is not247 supported or the ``index`` is out of bounds.248 249 If ``V4L2_CAP_IO_MC`` is set and the specified ``mbus_code``250 is unsupported, then also return this error code.251