From: Nico Grunbaum <na-g@nostrum.com>
Date: Mon, 26 Jul 2021 22:51:00 -0700
Subject: Bug 1654112 - fix timestamp issues with RTP sources; r=mjf

Differential Revision: https://phabricator.services.mozilla.com/D120930
Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/de8c14e4972f717bf937b6f2fffcd08c35e21ced
---
 modules/rtp_rtcp/source/source_tracker.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/modules/rtp_rtcp/source/source_tracker.cc b/modules/rtp_rtcp/source/source_tracker.cc
index 676dab8c2b..08d68a6d03 100644
--- a/modules/rtp_rtcp/source/source_tracker.cc
+++ b/modules/rtp_rtcp/source/source_tracker.cc
@@ -57,7 +57,8 @@ void SourceTracker::OnFrameDelivered(const RtpPacketInfos& packet_infos,
       SourceEntry& entry = UpdateEntry(key);
       last_received_csrcs_.push_back(csrc);
 
-      entry.timestamp = delivery_time;
+      const auto packet_time = packet_info.receive_time();
+      entry.timestamp = packet_time.ms() ? packet_time : delivery_time;
       entry.audio_level = packet_info.audio_level();
       entry.absolute_capture_time = packet_info.absolute_capture_time();
       entry.local_capture_clock_offset =
@@ -122,6 +123,10 @@ std::vector<RtpSource> SourceTracker::GetSources() const {
             .local_capture_clock_offset = entry.local_capture_clock_offset});
   }
 
+  std::sort(sources.begin(), sources.end(), [](const auto &a, const auto &b){
+    return a.timestamp().ms() > b.timestamp().ms();
+  });
+
   return sources;
 }