diff options
Diffstat (limited to 'Documentation/media/uapi/v4l/vidioc-enum-fmt.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/vidioc-enum-fmt.rst | 165 |
1 files changed, 64 insertions, 101 deletions
diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst index 90996f69d6ae..a2adaa4bd4dd 100644 --- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst +++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst @@ -15,7 +15,8 @@ VIDIOC_ENUM_FMT - Enumerate image formats Synopsis ======== -.. cpp:function:: int ioctl( int fd, int request, struct v4l2_fmtdesc *argp ) +.. c:function:: int ioctl( int fd, VIDIOC_ENUM_FMT, struct v4l2_fmtdesc *argp ) + :name: VIDIOC_ENUM_FMT Arguments @@ -24,9 +25,6 @@ Arguments ``fd`` File descriptor returned by :ref:`open() <func-open>`. -``request`` - VIDIOC_ENUM_FMT - ``argp`` @@ -34,98 +32,73 @@ Description =========== To enumerate image formats applications initialize the ``type`` and -``index`` field of struct :ref:`v4l2_fmtdesc <v4l2-fmtdesc>` and call +``index`` field of struct :c:type:`v4l2_fmtdesc` and call the :ref:`VIDIOC_ENUM_FMT` ioctl with a pointer to this structure. Drivers fill the rest of the structure or return an ``EINVAL`` error code. All formats are enumerable by beginning at index zero and incrementing by one until ``EINVAL`` is returned. -.. note:: After switching input or output the list of enumerated image +.. note:: + + After switching input or output the list of enumerated image formats may be different. -.. _v4l2-fmtdesc: +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. c:type:: v4l2_fmtdesc .. flat-table:: struct v4l2_fmtdesc :header-rows: 0 :stub-columns: 0 :widths: 1 1 2 - - - .. row 1 - - - __u32 - - - ``index`` - - - Number of the format in the enumeration, set by the application. - This is in no way related to the ``pixelformat`` field. - - - .. row 2 - - - __u32 - - - ``type`` - - - Type of the data stream, set by the application. Only these types - are valid here: ``V4L2_BUF_TYPE_VIDEO_CAPTURE``, - ``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``, - ``V4L2_BUF_TYPE_VIDEO_OUTPUT``, - ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE`` and - ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See :ref:`v4l2-buf-type`. - - - .. row 3 - - - __u32 - - - ``flags`` - - - See :ref:`fmtdesc-flags` - - - .. row 4 - - - __u8 - - - ``description``\ [32] - - - Description of the format, a NUL-terminated ASCII string. This - information is intended for the user, for example: "YUV 4:2:2". - - - .. row 5 - - - __u32 - - - ``pixelformat`` - - - The image format identifier. This is a four character code as - computed by the v4l2_fourcc() macro: - - - .. row 6 - - - :cspan:`2` - - - .. _v4l2-fourcc: - .. code-block:: c - - #define v4l2_fourcc(a,b,c,d) (((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24)) - - Several image formats are already defined by this specification in - :ref:`pixfmt`. - - .. attention:: These codes are not the same as those used - in the Windows world. - - - .. row 7 - - - __u32 - - - ``reserved``\ [4] - - - Reserved for future extensions. Drivers must set the array to - zero. - - + * - __u32 + - ``index`` + - Number of the format in the enumeration, set by the application. + This is in no way related to the ``pixelformat`` field. + * - __u32 + - ``type`` + - Type of the data stream, set by the application. Only these types + are valid here: ``V4L2_BUF_TYPE_VIDEO_CAPTURE``, + ``V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE``, + ``V4L2_BUF_TYPE_VIDEO_OUTPUT``, + ``V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE`` and + ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. See :c:type:`v4l2_buf_type`. + * - __u32 + - ``flags`` + - See :ref:`fmtdesc-flags` + * - __u8 + - ``description``\ [32] + - Description of the format, a NUL-terminated ASCII string. This + information is intended for the user, for example: "YUV 4:2:2". + * - __u32 + - ``pixelformat`` + - The image format identifier. This is a four character code as + computed by the v4l2_fourcc() macro: + * - :cspan:`2` + + .. _v4l2-fourcc: + + ``#define v4l2_fourcc(a,b,c,d)`` + + ``(((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24))`` + + Several image formats are already defined by this specification in + :ref:`pixfmt`. + + .. attention:: + + These codes are not the same as those used + in the Windows world. + * - __u32 + - ``reserved``\ [4] + - Reserved for future extensions. Drivers must set the array to + zero. + + + +.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| .. _fmtdesc-flags: @@ -134,24 +107,14 @@ one until ``EINVAL`` is returned. :stub-columns: 0 :widths: 3 1 4 - - - .. row 1 - - - ``V4L2_FMT_FLAG_COMPRESSED`` - - - 0x0001 - - - This is a compressed format. - - - .. row 2 - - - ``V4L2_FMT_FLAG_EMULATED`` - - - 0x0002 - - - This format is not native to the device but emulated through - software (usually libv4l2), where possible try to use a native - format instead for better performance. + * - ``V4L2_FMT_FLAG_COMPRESSED`` + - 0x0001 + - This is a compressed format. + * - ``V4L2_FMT_FLAG_EMULATED`` + - 0x0002 + - This format is not native to the device but emulated through + software (usually libv4l2), where possible try to use a native + format instead for better performance. Return Value @@ -162,5 +125,5 @@ appropriately. The generic error codes are described at the :ref:`Generic Error Codes <gen-errors>` chapter. EINVAL - The struct :ref:`v4l2_fmtdesc <v4l2-fmtdesc>` ``type`` is not + The struct :c:type:`v4l2_fmtdesc` ``type`` is not supported or the ``index`` is out of bounds. |