From 545646cccba243236e10362fe7325f89be57da1f Mon Sep 17 00:00:00 2001
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Date: Tue, 18 Jul 2017 11:28:37 -0400
Subject: [PATCH] v4l2: Fix 4K colorimetry

Since 1.6, the transfer function for BT2020 has been changed from BT709
to BT2020_12. It's the same function, but with more precision. As a side
effect, the V4L2 colorpsace didn't match GStreamer colorspace. When
GStreamer ended up making a guess, it would not match anything supported
by V4L2 anymore. This this by using BT2020_12 for BT2020 colorspace and
BT2020 transfer function in replacement of BT709 whenever a 4K
resolution is detected.

Upstream-Status: Backport
Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>

---
 sys/v4l2/gstv4l2object.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 61244455f..aae2c55e7 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -1960,7 +1960,7 @@ gst_v4l2_object_get_colorspace (struct v4l2_format *fmt,
     case V4L2_COLORSPACE_BT2020:
       cinfo->range = GST_VIDEO_COLOR_RANGE_16_235;
       cinfo->matrix = GST_VIDEO_COLOR_MATRIX_BT2020;
-      cinfo->transfer = GST_VIDEO_TRANSFER_BT709;
+      cinfo->transfer = GST_VIDEO_TRANSFER_BT2020_12;
       cinfo->primaries = GST_VIDEO_COLOR_PRIMARIES_BT2020;
       break;
     case V4L2_COLORSPACE_SMPTE240M:
@@ -2062,7 +2062,10 @@ gst_v4l2_object_get_colorspace (struct v4l2_format *fmt,
 
   switch (transfer) {
     case V4L2_XFER_FUNC_709:
-      cinfo->transfer = GST_VIDEO_TRANSFER_BT709;
+      if (fmt->fmt.pix.height > 2160)
+        cinfo->transfer = GST_VIDEO_TRANSFER_BT2020_12;
+      else
+        cinfo->transfer = GST_VIDEO_TRANSFER_BT709;
       break;
     case V4L2_XFER_FUNC_SRGB:
       cinfo->transfer = GST_VIDEO_TRANSFER_SRGB;
-- 
2.14.1