From 78e22f902404cc08512e949e08be3a0e49b0a1d9 Mon Sep 17 00:00:00 2001
From: alwu <alwu@mozilla.com>
Date: Mon, 24 Jun 2024 13:33:01 +0000
Subject: [PATCH] Bug 1900191 - use default duration if exists.
 r=media-playback-reviewers,karlt

Differential Revision: https://phabricator.services.mozilla.com/D214648
---
 dom/media/webm/NesteggPacketHolder.h | 20 +++++++++++++++++---
 dom/media/webm/WebMDemuxer.cpp       | 10 +++++++---
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/dom/media/webm/NesteggPacketHolder.h b/dom/media/webm/NesteggPacketHolder.h
index 7c74f752d35f8..e1e7822106d5a 100644
--- a/dom/media/webm/NesteggPacketHolder.h
+++ b/dom/media/webm/NesteggPacketHolder.h
@@ -25,11 +25,12 @@ class NesteggPacketHolder {
         mOffset(-1),
         mTimestamp(-1),
         mDuration(-1),
+        mDefaultDuration(-1),
         mTrack(0),
         mIsKeyframe(false) {}
 
-  bool Init(nestegg_packet* aPacket, int64_t aOffset, unsigned aTrack,
-            bool aIsKeyframe) {
+  bool Init(nestegg_packet* aPacket, nestegg* aContext, int64_t aOffset,
+            unsigned aTrack, bool aIsKeyframe) {
     uint64_t timestamp_ns;
     if (nestegg_packet_tstamp(aPacket, &timestamp_ns) == -1) {
       return false;
@@ -47,6 +48,10 @@ class NesteggPacketHolder {
     if (!nestegg_packet_duration(aPacket, &duration_ns)) {
       mDuration = duration_ns / 1000;
     }
+    if (!nestegg_track_default_duration(aContext, mTrack, &duration_ns)) {
+      mDefaultDuration = duration_ns / 1000;
+    }
+
     return true;
   }
 
@@ -66,6 +71,10 @@ class NesteggPacketHolder {
     MOZ_ASSERT(IsInitialized());
     return mDuration;
   }
+  int64_t DefaultDuration() const {
+    MOZ_ASSERT(IsInitialized());
+    return mDefaultDuration;
+  }
   unsigned Track() {
     MOZ_ASSERT(IsInitialized());
     return mTrack;
@@ -78,7 +87,7 @@ class NesteggPacketHolder {
  private:
   ~NesteggPacketHolder() { nestegg_free_packet(mPacket); }
 
-  bool IsInitialized() { return mOffset >= 0; }
+  bool IsInitialized() const { return mOffset >= 0; }
 
   nestegg_packet* mPacket;
 
@@ -90,8 +99,13 @@ class NesteggPacketHolder {
   int64_t mTimestamp;
 
   // Packet duration in microseconds; -1 if unknown or retrieval failed.
+  // https://www.webmproject.org/docs/container/#BlockDuration
   int64_t mDuration;
 
+  // Default durtaion in microseconds; -1 if unknown or retrieval failed.
+  // https://www.webmproject.org/docs/container/#Duration
+  int64_t mDefaultDuration;
+
   // Track ID.
   unsigned mTrack;
 
diff --git a/dom/media/webm/WebMDemuxer.cpp b/dom/media/webm/WebMDemuxer.cpp
index 8b8b10b4673cf..5cb529bec15f2 100644
--- a/dom/media/webm/WebMDemuxer.cpp
+++ b/dom/media/webm/WebMDemuxer.cpp
@@ -599,9 +599,11 @@ nsresult WebMDemuxer::GetNextPacket(TrackInfo::TrackType aType,
   }
   int64_t tstamp = holder->Timestamp();
   int64_t duration = holder->Duration();
+  int64_t defaultDuration = holder->DefaultDuration();
   if (aType == TrackInfo::TrackType::kVideoTrack) {
-    WEBM_DEBUG("GetNextPacket(video): tstamp=%" PRId64 ", duration=%" PRId64,
-               tstamp, duration);
+    WEBM_DEBUG("GetNextPacket(video): tstamp=%" PRId64 ", duration=%" PRId64
+               ", defaultDuration=%" PRId64,
+               tstamp, duration, defaultDuration);
   }
 
   // The end time of this frame is the start time of the next frame. Fetch
@@ -625,6 +627,8 @@ nsresult WebMDemuxer::GetNextPacket(TrackInfo::TrackType aType,
       next_tstamp = tstamp + duration;
     } else if (lastFrameTime.isSome()) {
       next_tstamp = tstamp + (tstamp - lastFrameTime.ref());
+    } else if (defaultDuration >= 0) {
+      next_tstamp = tstamp + defaultDuration;
     } else if (mVideoFrameEndTimeBeforeReset) {
       WEBM_DEBUG("Setting next timestamp to be %" PRId64 " us",
                  mVideoFrameEndTimeBeforeReset->ToMicroseconds());
@@ -949,7 +953,7 @@ nsresult WebMDemuxer::DemuxPacket(TrackInfo::TrackType aType,
 
   int64_t offset = Resource(aType).Tell();
   RefPtr<NesteggPacketHolder> holder = new NesteggPacketHolder();
-  if (!holder->Init(packet, offset, track, false)) {
+  if (!holder->Init(packet, Context(aType), offset, track, false)) {
     WEBM_DEBUG("NesteggPacketHolder::Init: error");
     return NS_ERROR_DOM_MEDIA_DEMUXER_ERR;
   }