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authorHans Verkuil <hverkuil-cisco@xs4all.nl>2019-04-23 10:05:09 -0400
committerMauro Carvalho Chehab <mchehab+samsung@kernel.org>2019-05-08 14:01:57 -0400
commit823a633eeb7775171cbb9f423401316504745dc7 (patch)
treeb4703a73ba61a5eead7ef05a79fa5f97a25dd8e6 /Documentation/media
parent16204b8a1c1af77725533b77936e6c73953486ae (diff)
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 The list of FIELD values was outdated, so it was a bit confusing.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')
-rw-r--r--Documentation/media/uapi/v4l/field-order.rst16
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.