[PATCH] Implement Limited Video Range

* [PATCH] Implement Limited Video Range
@ 2015-11-30  7:08 Peter Frühberger
  2015-11-30  8:43 ` Daniel Vetter
  0 siblings, 1 reply; 8+ messages in thread
From: Peter Frühberger @ 2015-11-30  7:08 UTC (permalink / raw)
  To: intel-gfx


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(Resent cause of moderation)

This implements a highly needed feature in a minimal non instructive way.
Consider a Limited Range display (like most TVs) where you want to watch a
decoded video. The TV is set to limited range and the intel driver also
uses full scaling Limited 16:235 mode, e.g. if you display the gray value
16 - the driver will postprocess it to something like ~ 22.

The following happens currently in linux intel video world:
Video is decoded with e.g. vaapi, the decoded surface is either used via
EGL directly in Limited Range. Limited Range processing takes place and at
the end while rendering the intel driver will scale down the limited range
data again as it cannot distunguish of the data it gets when e.g. rendering
with OpenGL like we succesfully do in kodi.

Another use case is vaapi when using the old vaCopySurfaceGLX
(vaPutSurface) which would automatically use BT601 / BT709 matrix to
upscale the content without any dithering to Full Range RGB. Later on this
is scaled down again with the Limited 16:235 setting and output. Quality
degrades two times.

Users and applications widely used want to make sure that colors appear on
screen like they were processed after the last processing step. In video
case two use cases make sense:

a) scaling limited range to full range with dithering applied when you need
to output fullrange
b) already having limited range and outputting that without any further
touching by the driver

Use case a) is already possible. Usecase b) will be possible with the
attached patch. It is a possibility to get Limited Range on screen in
perfect quality in 2k15.

For the future a userspace api to provide info frames and so on in a
generic way should be considered but until we have this I bet we have 2
years to go. This solution also works on X11 (without wayland) and is
useful for existing applications.

Thanks much for consideration.

---
>From deaa9d730c08aefefe3671d073d93d970bb39a31 Mon Sep 17 00:00:00 2001
From: fritsch <peter.fruehberger@gmail.com>
Date: Sun, 29 Nov 2015 16:38:14 +0100
Subject: [PATCH] Intel: Implement Video Color Range

---
 drivers/gpu/drm/i915/i915_drv.h      |  1 +
 drivers/gpu/drm/i915/intel_display.c |  4 ++--
 drivers/gpu/drm/i915/intel_drv.h     |  8 ++++++++
 drivers/gpu/drm/i915/intel_hdmi.c    | 17 +++++++++++++++--
 drivers/gpu/drm/i915/intel_modes.c   |  1 +
 5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h
b/drivers/gpu/drm/i915/i915_drv.h
index 95bb27d..e453461 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3449,6 +3449,7 @@ int intel_freq_opcode(struct drm_i915_private
*dev_priv, int val);
 #define INTEL_BROADCAST_RGB_AUTO 0
 #define INTEL_BROADCAST_RGB_FULL 1
 #define INTEL_BROADCAST_RGB_LIMITED 2
+#define INTEL_BROADCAST_RGB_VIDEO 3

 static inline uint32_t i915_vgacntrl_reg(struct drm_device *dev)
 {
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 71860f8..ea40d81 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8605,7 +8605,7 @@ static void intel_set_pipe_csc(struct drm_crtc *crtc)
   * consideration.
   */

- if (intel_crtc->config->limited_color_range)
+ if (intel_crtc->config->limited_color_range &&
!intel_crtc->config->video_color_range)
  coeff = ((235 - 16) * (1 << 12) / 255) & 0xff8; /* 0.xxx... */

  /*
@@ -8629,7 +8629,7 @@ static void intel_set_pipe_csc(struct drm_crtc *crtc)
  if (INTEL_INFO(dev)->gen > 6) {
  uint16_t postoff = 0;

- if (intel_crtc->config->limited_color_range)
+ if (intel_crtc->config->limited_color_range &&
!intel_crtc->config->video_color_range)
  postoff = (16 * (1 << 12) / 255) & 0x1fff;

  I915_WRITE(PIPE_CSC_POSTOFF_HI(pipe), postoff);
diff --git a/drivers/gpu/drm/i915/intel_drv.h
b/drivers/gpu/drm/i915/intel_drv.h
index 0598932..6940243 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -372,6 +372,13 @@ struct intel_crtc_state {
   */
  bool limited_color_range;

+ /*
+  *
+  * Use reduced/limited/broadcast rgb range without compressing.
+  *
+  */
+ bool video_color_range;
+
  /* DP has a bunch of special case unfortunately, so mark the pipe
   * accordingly. */
  bool has_dp_encoder;
@@ -682,6 +689,7 @@ struct intel_hdmi {
  int ddc_bus;
  bool limited_color_range;
  bool color_range_auto;
+ bool color_range_video;
  bool has_hdmi_sink;
  bool has_audio;
  enum hdmi_force_audio force_audio;
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c
b/drivers/gpu/drm/i915/intel_hdmi.c
index 9eafa19..dc78760 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -464,7 +464,8 @@ static void intel_hdmi_set_avi_infoframe(struct
drm_encoder *encoder,
  }

  if (intel_hdmi->rgb_quant_range_selectable) {
- if (intel_crtc->config->limited_color_range)
+ if (intel_crtc->config->limited_color_range ||
+     intel_crtc->config->video_color_range)
  frame.avi.quantization_range =
  HDMI_QUANTIZATION_RANGE_LIMITED;
  else
@@ -1266,6 +1267,8 @@ bool intel_hdmi_compute_config(struct intel_encoder
*encoder,
  pipe_config->limited_color_range =
  intel_hdmi->limited_color_range;
  }
+ if (intel_hdmi->color_range_video)
+               pipe_config->video_color_range = true;

  if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK) {
  pipe_config->pixel_multiplier = 2;
@@ -1485,25 +1488,35 @@ intel_hdmi_set_property(struct drm_connector
*connector,
  if (property == dev_priv->broadcast_rgb_property) {
  bool old_auto = intel_hdmi->color_range_auto;
  bool old_range = intel_hdmi->limited_color_range;
+ bool old_range_video = intel_hdmi->color_range_video;

  switch (val) {
  case INTEL_BROADCAST_RGB_AUTO:
  intel_hdmi->color_range_auto = true;
+ intel_hdmi->color_range_video = false;
  break;
  case INTEL_BROADCAST_RGB_FULL:
  intel_hdmi->color_range_auto = false;
  intel_hdmi->limited_color_range = false;
+ intel_hdmi->color_range_video = false;
  break;
  case INTEL_BROADCAST_RGB_LIMITED:
  intel_hdmi->color_range_auto = false;
  intel_hdmi->limited_color_range = true;
+ intel_hdmi->color_range_video = false;
+ break;
+ case INTEL_BROADCAST_RGB_VIDEO:
+                        intel_hdmi->color_range_auto = false;
+                        intel_hdmi->limited_color_range = true;
+                        intel_hdmi->color_range_video = true;
  break;
  default:
  return -EINVAL;
  }

  if (old_auto == intel_hdmi->color_range_auto &&
-     old_range == intel_hdmi->limited_color_range)
+     old_range == intel_hdmi->limited_color_range &&
+     old_range_video == intel_hdmi->color_range_video)
  return 0;

  goto done;
diff --git a/drivers/gpu/drm/i915/intel_modes.c
b/drivers/gpu/drm/i915/intel_modes.c
index 38a4c8c..c49681a 100644
--- a/drivers/gpu/drm/i915/intel_modes.c
+++ b/drivers/gpu/drm/i915/intel_modes.c
@@ -103,6 +103,7 @@ static const struct drm_prop_enum_list
broadcast_rgb_names[] = {
  { INTEL_BROADCAST_RGB_AUTO, "Automatic" },
  { INTEL_BROADCAST_RGB_FULL, "Full" },
  { INTEL_BROADCAST_RGB_LIMITED, "Limited 16:235" },
+ { INTEL_BROADCAST_RGB_VIDEO, "Video 16:235 pass-through" },
 };

 void
-- 
2.5.0

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