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authorLinus Torvalds <torvalds@linux-foundation.org>2017-02-14 06:29:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-14 06:29:21 -0800
commit747ae0a96f1a78b35c5a3d93ad37a16655e16340 (patch)
tree880b33cf70674a5cccc6508cc327f01e93971017 /Documentation
parent7089db84e356562f8ba737c29e472cc42d530dbc (diff)
parent42980da2eb7eb9695d8efc0c0ef145cbbb993b2c (diff)
downloadlinux-747ae0a96f1a78b35c5a3d93ad37a16655e16340.tar.bz2
Merge tag 'media/v4.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media fixes from Mauro Carvalho Chehab: "A colorspace regression fix in V4L2 core and a CEC core bug that makes it discard valid messages" * tag 'media/v4.10-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: [media] cec: initiator should be the same as the destination for, poll [media] videodev2.h: go back to limited range Y'CbCr for SRGB and, ADOBERGB
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/media/uapi/v4l/pixfmt-007.rst23
1 files changed, 17 insertions, 6 deletions
diff --git a/Documentation/media/uapi/v4l/pixfmt-007.rst b/Documentation/media/uapi/v4l/pixfmt-007.rst
index 44bb5a7059b3..95a23a28c595 100644
--- a/Documentation/media/uapi/v4l/pixfmt-007.rst
+++ b/Documentation/media/uapi/v4l/pixfmt-007.rst
@@ -211,7 +211,13 @@ Colorspace sRGB (V4L2_COLORSPACE_SRGB)
The :ref:`srgb` standard defines the colorspace used by most webcams
and computer graphics. The default transfer function is
``V4L2_XFER_FUNC_SRGB``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is full range.
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited range.
+
+Note that the :ref:`sycc` standard specifies full range quantization,
+however all current capture hardware supported by the kernel convert
+R'G'B' to limited range Y'CbCr. So choosing full range as the default
+would break how applications interpret the quantization range.
+
The chromaticities of the primary colors and the white reference are:
@@ -276,7 +282,7 @@ the following ``V4L2_YCBCR_ENC_601`` encoding as defined by :ref:`sycc`:
Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
[-0.5…0.5]. This transform is identical to one defined in SMPTE
-170M/BT.601. The Y'CbCr quantization is full range.
+170M/BT.601. The Y'CbCr quantization is limited range.
.. _col-adobergb:
@@ -288,10 +294,15 @@ The :ref:`adobergb` standard defines the colorspace used by computer
graphics that use the AdobeRGB colorspace. This is also known as the
:ref:`oprgb` standard. The default transfer function is
``V4L2_XFER_FUNC_ADOBERGB``. The default Y'CbCr encoding is
-``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is full
-range. The chromaticities of the primary colors and the white reference
-are:
+``V4L2_YCBCR_ENC_601``. The default Y'CbCr quantization is limited
+range.
+
+Note that the :ref:`oprgb` standard specifies full range quantization,
+however all current capture hardware supported by the kernel convert
+R'G'B' to limited range Y'CbCr. So choosing full range as the default
+would break how applications interpret the quantization range.
+The chromaticities of the primary colors and the white reference are:
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
@@ -344,7 +355,7 @@ the following ``V4L2_YCBCR_ENC_601`` encoding:
Y' is clamped to the range [0…1] and Cb and Cr are clamped to the range
[-0.5…0.5]. This transform is identical to one defined in SMPTE
-170M/BT.601. The Y'CbCr quantization is full range.
+170M/BT.601. The Y'CbCr quantization is limited range.
.. _col-bt2020: