All video capture and output devices must report the current field
order. Some drivers may permit the selection of a different order, to
this end applications initialize the ``field`` field of struct
-:ref:`v4l2_pix_format <v4l2-pix-format>` before calling the
+:c:type:`v4l2_pix_format` before calling the
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl. If this is not desired it
should have the value ``V4L2_FIELD_ANY`` (0).
-.. _v4l2-field:
-
enum v4l2_field
===============
+.. c:type:: v4l2_field
+
+.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}|
+
.. flat-table::
:header-rows: 0
:stub-columns: 0
:widths: 3 1 4
-
- - .. row 1
-
- - ``V4L2_FIELD_ANY``
-
- - 0
-
- - Applications request this field order when any one of the
- ``V4L2_FIELD_NONE``, ``V4L2_FIELD_TOP``, ``V4L2_FIELD_BOTTOM``, or
- ``V4L2_FIELD_INTERLACED`` formats is acceptable. Drivers choose
- depending on hardware capabilities or e. g. the requested image
- size, and return the actual field order. Drivers must never return
- ``V4L2_FIELD_ANY``. If multiple field orders are possible the
- driver must choose one of the possible field orders during
- :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or
- :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`. struct
- :ref:`v4l2_buffer <v4l2-buffer>` ``field`` can never be
- ``V4L2_FIELD_ANY``.
-
- - .. row 2
-
- - ``V4L2_FIELD_NONE``
-
- - 1
-
- - Images are in progressive format, not interlaced. The driver may
- also indicate this order when it cannot distinguish between
- ``V4L2_FIELD_TOP`` and ``V4L2_FIELD_BOTTOM``.
-
- - .. row 3
-
- - ``V4L2_FIELD_TOP``
-
- - 2
-
- - Images consist of the top (aka odd) field only.
-
- - .. row 4
-
- - ``V4L2_FIELD_BOTTOM``
-
- - 3
-
- - Images consist of the bottom (aka even) field only. Applications
- may wish to prevent a device from capturing interlaced images
- because they will have "comb" or "feathering" artefacts around
- moving objects.
-
- - .. row 5
-
- - ``V4L2_FIELD_INTERLACED``
-
- - 4
-
- - Images contain both fields, interleaved line by line. The temporal
- order of the fields (whether the top or bottom field is first
- transmitted) depends on the current video standard. M/NTSC
- transmits the bottom field first, all other standards the top
- field first.
-
- - .. row 6
-
- - ``V4L2_FIELD_SEQ_TB``
-
- - 5
-
- - Images contain both fields, the top field lines are stored first
- in memory, immediately followed by the bottom field lines. Fields
- are always stored in temporal order, the older one first in
- memory. Image sizes refer to the frame, not fields.
-
- - .. row 7
-
- - ``V4L2_FIELD_SEQ_BT``
-
- - 6
-
- - Images contain both fields, the bottom field lines are stored
- first in memory, immediately followed by the top field lines.
- Fields are always stored in temporal order, the older one first in
- memory. Image sizes refer to the frame, not fields.
-
- - .. row 8
-
- - ``V4L2_FIELD_ALTERNATE``
-
- - 7
-
- - The two fields of a frame are passed in separate buffers, in
- temporal order, i. e. the older one first. To indicate the field
- parity (whether the current field is a top or bottom field) the
- driver or application, depending on data direction, must set
- struct :ref:`v4l2_buffer <v4l2-buffer>` ``field`` to
- ``V4L2_FIELD_TOP`` or ``V4L2_FIELD_BOTTOM``. Any two successive
- fields pair to build a frame. If fields are successive, without
- any dropped fields between them (fields can drop individually),
- can be determined from the struct
- :ref:`v4l2_buffer <v4l2-buffer>` ``sequence`` field. This
- format cannot be selected when using the read/write I/O method
- since there is no way to communicate if a field was a top or
- bottom field.
-
- - .. row 9
-
- - ``V4L2_FIELD_INTERLACED_TB``
-
- - 8
-
- - Images contain both fields, interleaved line by line, top field
- first. The top field is transmitted first.
-
- - .. row 10
-
- - ``V4L2_FIELD_INTERLACED_BT``
-
- - 9
-
- - Images contain both fields, interleaved line by line, top field
- first. The bottom field is transmitted first.
+ * - ``V4L2_FIELD_ANY``
+ - 0
+ - Applications request this field order when any one of the
+ ``V4L2_FIELD_NONE``, ``V4L2_FIELD_TOP``, ``V4L2_FIELD_BOTTOM``, or
+ ``V4L2_FIELD_INTERLACED`` formats is acceptable. Drivers choose
+ depending on hardware capabilities or e. g. the requested image
+ size, and return the actual field order. Drivers must never return
+ ``V4L2_FIELD_ANY``. If multiple field orders are possible the
+ driver must choose one of the possible field orders during
+ :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or
+ :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`. struct
+ :c:type:`v4l2_buffer` ``field`` can never be
+ ``V4L2_FIELD_ANY``.
+ * - ``V4L2_FIELD_NONE``
+ - 1
+ - Images are in progressive format, not interlaced. The driver may
+ also indicate this order when it cannot distinguish between
+ ``V4L2_FIELD_TOP`` and ``V4L2_FIELD_BOTTOM``.
+ * - ``V4L2_FIELD_TOP``
+ - 2
+ - Images consist of the top (aka odd) field only.
+ * - ``V4L2_FIELD_BOTTOM``
+ - 3
+ - Images consist of the bottom (aka even) field only. Applications
+ may wish to prevent a device from capturing interlaced images
+ because they will have "comb" or "feathering" artefacts around
+ moving objects.
+ * - ``V4L2_FIELD_INTERLACED``
+ - 4
+ - Images contain both fields, interleaved line by line. The temporal
+ order of the fields (whether the top or bottom field is first
+ transmitted) depends on the current video standard. M/NTSC
+ transmits the bottom field first, all other standards the top
+ field first.
+ * - ``V4L2_FIELD_SEQ_TB``
+ - 5
+ - Images contain both fields, the top field lines are stored first
+ in memory, immediately followed by the bottom field lines. Fields
+ are always stored in temporal order, the older one first in
+ memory. Image sizes refer to the frame, not fields.
+ * - ``V4L2_FIELD_SEQ_BT``
+ - 6
+ - Images contain both fields, the bottom field lines are stored
+ first in memory, immediately followed by the top field lines.
+ Fields are always stored in temporal order, the older one first in
+ memory. Image sizes refer to the frame, not fields.
+ * - ``V4L2_FIELD_ALTERNATE``
+ - 7
+ - The two fields of a frame are passed in separate buffers, in
+ temporal order, i. e. the older one first. To indicate the field
+ parity (whether the current field is a top or bottom field) the
+ driver or application, depending on data direction, must set
+ struct :c:type:`v4l2_buffer` ``field`` to
+ ``V4L2_FIELD_TOP`` or ``V4L2_FIELD_BOTTOM``. Any two successive
+ fields pair to build a frame. If fields are successive, without
+ any dropped fields between them (fields can drop individually),
+ can be determined from the struct
+ :c:type:`v4l2_buffer` ``sequence`` field. This
+ format cannot be selected when using the read/write I/O method
+ since there is no way to communicate if a field was a top or
+ bottom field.
+ * - ``V4L2_FIELD_INTERLACED_TB``
+ - 8
+ - Images contain both fields, interleaved line by line, top field
+ first. The top field is transmitted first.
+ * - ``V4L2_FIELD_INTERLACED_BT``
+ - 9
+ - Images contain both fields, interleaved line by line, top field
+ first. The bottom field is transmitted first.
projects / cascardo / linux.git / blobdiff