From be5a0a7fa0ba14f209ef4a18f972ccd00c7e4ed9 Mon Sep 17 00:00:00 2001
From: Steve Lhomme <slhomme@matroska.org>
Date: Sun, 14 Mar 2021 15:39:08 +0100
Subject: [PATCH] documentation image flipping through
 ProjectionPoseYaw/ProjectionPosePitch

Fixes #327.
---
 ebml_matroska.xml | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/ebml_matroska.xml b/ebml_matroska.xml
index 6cb7a7512..5141e2507 100644
--- a/ebml_matroska.xml
+++ b/ebml_matroska.xml
@@ -844,7 +844,7 @@ in candelas per square meter (cd/m^2^).</documentation>
     <extension type="libmatroska" cppname="VideoLuminanceMin"/>
   </element>
   <element name="Projection" path="\Segment\Tracks\TrackEntry\Video\Projection" id="0x7670" type="master" minver="4" maxOccurs="1">
-    <documentation lang="en" purpose="definition">Describes the video projection details. Used to render spherical and VR videos.</documentation>
+    <documentation lang="en" purpose="definition">Describes the video projection details. Used to render spherical, VR videos or flipping videos horizontally/vertically.</documentation>
     <extension type="webmproject.org" webm="1"/>
     <extension type="libmatroska" cppname="VideoProjection"/>
   </element>
@@ -882,7 +882,9 @@ redundant framing information while preserving versioning and semantics between
 
 Value represents a clockwise rotation, in degrees, around the up vector. This rotation must be applied
 before any `ProjectionPosePitch` or `ProjectionPoseRoll` rotations.
-The value of this field should be in the -180 to 180 degree range.</documentation>
+The value of this field should be in the -180 to 180 degree range.
+
+Setting `ProjectionPoseYaw` to 180.0 degrees flips the image horizontally.</documentation>
     <extension type="webmproject.org" webm="1"/>
     <extension type="libmatroska" cppname="VideoProjectionPoseYaw"/>
   </element>
@@ -891,7 +893,9 @@ The value of this field should be in the -180 to 180 degree range.</documentatio
 
 Value represents a counter-clockwise rotation, in degrees, around the right vector. This rotation must be applied
 after the `ProjectionPoseYaw` rotation and before the `ProjectionPoseRoll` rotation.
-The value of this field should be in the -90 to 90 degree range.</documentation>
+The value of this field should be in the -90 to 90 degree range.
+
+Setting `ProjectionPosePitch` to 180.0 degrees flips the image vertically.</documentation>
     <extension type="webmproject.org" webm="1"/>
     <extension type="libmatroska" cppname="VideoProjectionPosePitch"/>
   </element>