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| author | Hans Verkuil <hverkuil-cisco@xs4all.nl> | 2019-04-23 17:05:09 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-05-08 21:01:57 +0300 |
| commit | 823a633eeb7775171cbb9f423401316504745dc7 (patch) | |
| tree | b4703a73ba61a5eead7ef05a79fa5f97a25dd8e6 /Documentation/media/uapi/v4l | |
| parent | 16204b8a1c1af77725533b77936e6c73953486ae (diff) | |
| download | linux-823a633eeb7775171cbb9f423401316504745dc7.tar.xz | |
media: field-order.rst: clarify FIELD_ANY and FIELD_NONE
Rephrased the FIELD_ANY description: rather than explicitly list
field values, just say 'when any field format is acceptable'. The
list of FIELD values was outdated, so it was a bit confusing.
The FIELD_NONE description said that 'The driver may also indicate
this order when it cannot distinguish between V4L2_FIELD_TOP and
V4L2_FIELD_BOTTOM'. This is false, NONE really means a full frame
and userspace depends on that. So drop this line completely. There
are no drivers that do this anyway.
FIELD_TOP/BOTTOM/ALTERNATE indicate that the number of lines in the
buffer are that of a field, not frame, so returning NONE here would
cause huge problems.
Finally attempt to clarify 'progressive' and 'interlaced' a little
bit.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/media/uapi/v4l')
| -rw-r--r-- | Documentation/media/uapi/v4l/field-order.rst | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/Documentation/media/uapi/v4l/field-order.rst b/Documentation/media/uapi/v4l/field-order.rst index 3fb473e3b8e2..d640e922a974 100644 --- a/Documentation/media/uapi/v4l/field-order.rst +++ b/Documentation/media/uapi/v4l/field-order.rst @@ -75,12 +75,11 @@ enum v4l2_field * - ``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 + - Applications request this field order when any field format + 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 @@ -88,9 +87,8 @@ enum v4l2_field ``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``. + - Images are in progressive (frame-based) format, not interlaced + (field-based). * - ``V4L2_FIELD_TOP`` - 2 - Images consist of the top (aka odd) field only. |