media: media/doc: rename and reorder pixfmt files

After the DocBook conversion a number of pixfmt description files just
had a number in the filename (pix-fmt-004, 006, etc) which was not very
descriptive.

Rename them.

Note that pixfmt-008.rst was folded into colorspaces-details.rst, so
that file is deleted. It's easier to maintain that way.

Also moved the colorspace sections to the end of the chapter. The old
order was weird: the "Standard Image Formats" section (an intro into
pixel formats) was followed by the colorspace sections instead of the
pixel format descriptions.

Moving it to the end resolved that issue.

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/Documentation/media/uapi/v4l/pixfmt-intro.rst b/Documentation/media/uapi/v4l/pixfmt-intro.rst
new file mode 100644
index 0000000..4bc116a
--- /dev/null
+++ b/Documentation/media/uapi/v4l/pixfmt-intro.rst
@@ -0,0 +1,51 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+**********************
+Standard Image Formats
+**********************
+
+In order to exchange images between drivers and applications, it is
+necessary to have standard image data formats which both sides will
+interpret the same way. V4L2 includes several such formats, and this
+section is intended to be an unambiguous specification of the standard
+image data formats in V4L2.
+
+V4L2 drivers are not limited to these formats, however. Driver-specific
+formats are possible. In that case the application may depend on a codec
+to convert images to one of the standard formats when needed. But the
+data can still be stored and retrieved in the proprietary format. For
+example, a device may support a proprietary compressed format.
+Applications can still capture and save the data in the compressed
+format, saving much disk space, and later use a codec to convert the
+images to the X Windows screen format when the video is to be displayed.
+
+Even so, ultimately, some standard formats are needed, so the V4L2
+specification would not be complete without well-defined standard
+formats.
+
+The V4L2 standard formats are mainly uncompressed formats. The pixels
+are always arranged in memory from left to right, and from top to
+bottom. The first byte of data in the image buffer is always for the
+leftmost pixel of the topmost row. Following that is the pixel
+immediately to its right, and so on until the end of the top row of
+pixels. Following the rightmost pixel of the row there may be zero or
+more bytes of padding to guarantee that each row of pixel data has a
+certain alignment. Following the pad bytes, if any, is data for the
+leftmost pixel of the second row from the top, and so on. The last row
+has just as many pad bytes after it as the other rows.
+
+In V4L2 each format has an identifier which looks like ``PIX_FMT_XXX``,
+defined in the :ref:`videodev2.h <videodev>` header file. These
+identifiers represent
+:ref:`four character (FourCC) codes <v4l2-fourcc>` which are also
+listed below, however they are not the same as those used in the Windows
+world.
+
+For some formats, data is stored in separate, discontiguous memory
+buffers. Those formats are identified by a separate set of FourCC codes
+and are referred to as "multi-planar formats". For example, a
+:ref:`YUV422 <V4L2-PIX-FMT-YUV422M>` frame is normally stored in one
+memory buffer, but it can also be placed in two or three separate
+buffers, with Y component in one buffer and CbCr components in another
+in the 2-planar version or with each component in its own buffer in the
+3-planar case. Those sub-buffers are referred to as "*planes*".