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| author | Luca Ceresoli <luca@lucaceresoli.net> | 2018-05-14 07:27:25 -0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2018-05-25 15:24:06 -0400 |
| commit | ff9273f5b87f1a5662a978c73ef684fec7b166fc (patch) | |
| tree | 9a566313205f5af098b039d94a1afc472e039b7b /Documentation/media/uapi/v4l/selection-api-005.rst | |
| parent | 579d76deb1b106af5987670389604381c31116eb (diff) | |
| download | op-kernel-dev-ff9273f5b87f1a5662a978c73ef684fec7b166fc.zip op-kernel-dev-ff9273f5b87f1a5662a978c73ef684fec7b166fc.tar.gz | |
media: docs: selection: rename files to something meaningful
These files have an automatically-generated numbering. Rename them
with a name that suggests their meaning.
Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/media/uapi/v4l/selection-api-005.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/selection-api-005.rst | 36 |
1 files changed, 0 insertions, 36 deletions
diff --git a/Documentation/media/uapi/v4l/selection-api-005.rst b/Documentation/media/uapi/v4l/selection-api-005.rst deleted file mode 100644 index 2ad30a4..0000000 --- a/Documentation/media/uapi/v4l/selection-api-005.rst +++ /dev/null @@ -1,36 +0,0 @@ -.. -*- coding: utf-8; mode: rst -*- - -.. _selection-vs-crop: - -******************************** -Comparison with old cropping API -******************************** - -The selection API was introduced to cope with deficiencies of previous -:ref:`API <crop>`, that was designed to control simple capture -devices. Later the cropping API was adopted by video output drivers. The -ioctls are used to select a part of the display were the video signal is -inserted. It should be considered as an API abuse because the described -operation is actually the composing. The selection API makes a clear -distinction between composing and cropping operations by setting the -appropriate targets. The V4L2 API lacks any support for composing to and -cropping from an image inside a memory buffer. The application could -configure a capture device to fill only a part of an image by abusing -V4L2 API. Cropping a smaller image from a larger one is achieved by -setting the field ``bytesperline`` at struct -:c:type:`v4l2_pix_format`. -Introducing an image offsets could be done by modifying field ``m_userptr`` -at struct -:c:type:`v4l2_buffer` before calling -:ref:`VIDIOC_QBUF`. Those operations should be avoided because they are not -portable (endianness), and do not work for macroblock and Bayer formats -and mmap buffers. The selection API deals with configuration of buffer -cropping/composing in a clear, intuitive and portable way. Next, with -the selection API the concepts of the padded target and constraints -flags are introduced. Finally, struct :c:type:`v4l2_crop` -and struct :c:type:`v4l2_cropcap` have no reserved -fields. Therefore there is no way to extend their functionality. The new -struct :c:type:`v4l2_selection` provides a lot of place -for future extensions. Driver developers are encouraged to implement -only selection API. The former cropping API would be simulated using the -new one. |
