From c9417645a22e5eed687a9a1105adbf29423f7a91 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20V=C3=B6lcker?=
 <65532189+bjornvolcker@users.noreply.github.com>
Date: Wed, 7 May 2025 14:57:12 +0200
Subject: [PATCH 1/2] Update MediaSigning.xml with additional timestamp

To get a proper marked duration of a signed GOP two timestamps should be transmitted. Currently, only a start timestamp is added. This change will add an end timestamp.
Even though it is technically possible to compute a duration after receiving 2 SEIs it will never be correctly marked.
---
 doc/MediaSigning.xml | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/doc/MediaSigning.xml b/doc/MediaSigning.xml
index 676bfc529..eb260a2ab 100644
--- a/doc/MediaSigning.xml
+++ b/doc/MediaSigning.xml
@@ -914,7 +914,7 @@
         <itemizedlist>
           <listitem>
             <para>Tag version (1 byte)</para>
-            <para>Version = 1</para>
+            <para>Version = 1-2</para>
           </listitem>
           <listitem>
             <para>Specification version (3 byte)</para>
@@ -933,9 +933,18 @@
           </listitem>
           <listitem>
             <para>The UTC (8 bytes) based time represented by the number of 100-nanosecond intervals
-              since January 1, 1601 of the I-frame leading the GOP.</para>
-            <para>The timestamp value is a 64 bit parameter and the 8 bytes should be written with
+              since January 1, 1601 of the frame leading the (partial) GOP.</para>
+            <para>The start timestamp value is a 64 bit parameter and the 8 bytes should be written with
+              little endian.</para>
+          </listitem>
+          <listitem>
+            <para>Only present from tag version 2.</para>
+            <para>The UTC (8 bytes) based time represented by the number of 100-nanosecond intervals
+              since January 1, 1601 of the frame leading the upcoming (partial) GOP.</para>
+            <para>The end timestamp value is a 64 bit parameter and the 8 bytes should be written with
               little endian.</para>
+            <para>The duration of the signed (partial) GOP can now be calculated as duration =
+              "end timestamp" - "start timestamp". Note that the end timestamp is exclusive.</para>
           </listitem>
           <listitem>
             <para>GOP counter (4 bytes)</para>

From 55de3222eff5fb74254e1878b039aca0b6cc3289 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20V=C3=B6lcker?=
 <65532189+bjornvolcker@users.noreply.github.com>
Date: Thu, 8 May 2025 14:59:28 +0200
Subject: [PATCH 2/2] Removes spec version

Replaced with Spec rev. Also tag version only presents latest.
---
 doc/MediaSigning.xml | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/doc/MediaSigning.xml b/doc/MediaSigning.xml
index eb260a2ab..5f7ae48b4 100644
--- a/doc/MediaSigning.xml
+++ b/doc/MediaSigning.xml
@@ -58,12 +58,6 @@
       signing feature, and also how an ONVIF client should validate the authenticity of a signed
       stream. Audio is outside of scope.</para>
   </chapter>
-  <chapter xml:id="chapter_spec_version">
-    <title>Specification version v1.0</title>
-    <para>This number should be updated when an update to the specification breaks the bitstream
-      format or when new features are added. Such features could be new ways of hashing or support
-      of more codecs.</para>
-  </chapter>
   <chapter xml:id="chapter_a3s_njq_bwb">
     <title>Normative references</title>
     <para>ITU-T Recommendation, H.264: Advanced video coding for generic audiovisual services</para>
@@ -914,7 +908,7 @@
         <itemizedlist>
           <listitem>
             <para>Tag version (1 byte)</para>
-            <para>Version = 1-2</para>
+            <para>Version = 2</para>
           </listitem>
           <listitem>
             <para>Specification version (3 byte)</para>