From 9040194d54de2453f54b3076ee321a5924fe7429 Mon Sep 17 00:00:00 2001
From: Zaggy1024 <zaggy1024@gmail.com>
Date: Sat, 12 Nov 2022 02:28:15 -0600
Subject: [PATCH] LibVideo: Make Matroska Block and Cluster timestamps absolute

---
 .../LibVideo/Containers/Matroska/Document.h         | 13 +++++++------
 .../Containers/Matroska/MatroskaDemuxer.cpp         |  4 +---
 .../LibVideo/Containers/Matroska/Reader.cpp         | 12 ++++++------
 Userland/Utilities/matroska.cpp                     |  2 +-
 4 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Document.h b/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
index eb7d8e24d5..96b2962c74 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
@@ -12,6 +12,7 @@
 #include <AK/NonnullOwnPtrVector.h>
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
+#include <AK/Time.h>
 #include <AK/Utf8View.h>
 #include <LibVideo/Color/CodingIndependentCodePoints.h>
 
@@ -152,8 +153,8 @@ public:
 
     u64 track_number() const { return m_track_number; }
     void set_track_number(u64 track_number) { m_track_number = track_number; }
-    i16 timestamp() const { return m_timestamp; }
-    void set_timestamp(i16 timestamp) { m_timestamp = timestamp; }
+    Time timestamp() const { return m_timestamp; }
+    void set_timestamp(Time timestamp) { m_timestamp = timestamp; }
     bool only_keyframes() const { return m_only_keyframes; }
     void set_only_keyframes(bool only_keyframes) { m_only_keyframes = only_keyframes; }
     bool invisible() const { return m_invisible; }
@@ -170,7 +171,7 @@ public:
 
 private:
     u64 m_track_number { 0 };
-    i16 m_timestamp { 0 };
+    Time m_timestamp { Time::zero() };
     bool m_only_keyframes { false };
     bool m_invisible { false };
     Lacing m_lacing { None };
@@ -180,11 +181,11 @@ private:
 
 class Cluster {
 public:
-    u64 timestamp() const { return m_timestamp; }
-    void set_timestamp(u64 timestamp) { m_timestamp = timestamp; }
+    Time timestamp() const { return m_timestamp; }
+    void set_timestamp(Time timestamp) { m_timestamp = timestamp; }
 
 private:
-    u64 m_timestamp;
+    Time m_timestamp { Time::zero() };
 };
 
 }
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
index 04920926f5..10984bd6de 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
@@ -72,10 +72,8 @@ DecoderErrorOr<NonnullOwnPtr<Sample>> MatroskaDemuxer::get_next_sample_for_track
         status.block = TRY(status.iterator.next_block());
         status.frame_index = 0;
     }
-    auto const& cluster = status.iterator.current_cluster();
-    Time timestamp = Time::from_nanoseconds((cluster.timestamp() + status.block->timestamp()) * TRY(m_reader.segment_information()).timestamp_scale());
     auto cicp = TRY(m_reader.track_for_track_number(track.identifier())).video_track()->color_format.to_cicp();
-    return make<VideoSample>(status.block->frame(status.frame_index++), cicp, timestamp);
+    return make<VideoSample>(status.block->frame(status.frame_index++), cicp, status.block->timestamp());
 }
 
 DecoderErrorOr<Time> MatroskaDemuxer::duration()
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
index 449262f327..de3c3cc54a 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
@@ -487,7 +487,7 @@ constexpr size_t get_element_id_size(u32 element_id)
     return sizeof(element_id) - (count_leading_zeroes(element_id) / 8);
 }
 
-static DecoderErrorOr<Cluster> parse_cluster(Streamer& streamer)
+static DecoderErrorOr<Cluster> parse_cluster(Streamer& streamer, u64 timestamp_scale)
 {
     Optional<u64> timestamp;
     size_t first_element_position = 0;
@@ -516,11 +516,11 @@ static DecoderErrorOr<Cluster> parse_cluster(Streamer& streamer)
     TRY_READ(streamer.seek_to_position(first_element_position));
 
     Cluster cluster;
-    cluster.set_timestamp(timestamp.release_value());
+    cluster.set_timestamp(Time::from_nanoseconds(timestamp.release_value() * timestamp_scale));
     return cluster;
 }
 
-static DecoderErrorOr<Block> parse_simple_block(Streamer& streamer)
+static DecoderErrorOr<Block> parse_simple_block(Streamer& streamer, Time cluster_timestamp, u64 timestamp_scale)
 {
     Block block;
 
@@ -529,7 +529,7 @@ static DecoderErrorOr<Block> parse_simple_block(Streamer& streamer)
     auto position_before_track_number = streamer.position();
     block.set_track_number(TRY_READ(streamer.read_variable_size_integer()));
 
-    block.set_timestamp(TRY_READ(streamer.read_i16()));
+    block.set_timestamp(cluster_timestamp + Time::from_nanoseconds(TRY_READ(streamer.read_i16()) * timestamp_scale));
 
     auto flags = TRY_READ(streamer.read_octet());
     block.set_only_keyframes((flags & (1u << 7u)) != 0);
@@ -627,10 +627,10 @@ DecoderErrorOr<Block> SampleIterator::next_block()
 
         if (element_id == CLUSTER_ELEMENT_ID) {
             dbgln_if(MATROSKA_DEBUG, "  Iterator is parsing new cluster.");
-            m_current_cluster = TRY(parse_cluster(streamer));
+            m_current_cluster = TRY(parse_cluster(streamer, m_timestamp_scale));
         } else if (element_id == SIMPLE_BLOCK_ID) {
             dbgln_if(MATROSKA_TRACE_DEBUG, "  Iterator is parsing new block.");
-            auto candidate_block = TRY(parse_simple_block(streamer));
+            auto candidate_block = TRY(parse_simple_block(streamer, m_current_cluster->timestamp(), m_timestamp_scale));
             if (candidate_block.track_number() == m_track_id)
                 block = move(candidate_block);
         } else {
diff --git a/Userland/Utilities/matroska.cpp b/Userland/Utilities/matroska.cpp
index 92a40ee8d7..5f287eaac6 100644
--- a/Userland/Utilities/matroska.cpp
+++ b/Userland/Utilities/matroska.cpp
@@ -56,7 +56,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
                 return block_result.release_error();
             }
             auto block = block_result.release_value();
-            outln("\t\tBlock at timestamp {}:", iterator.current_cluster().timestamp() + block.timestamp());
+            outln("\t\tBlock at timestamp {}ms:", block.timestamp().to_milliseconds());
             outln("\t\t\tContains {} frames", block.frame_count());
             outln("\t\t\tLacing is {}", static_cast<u8>(block.lacing()));
         }