Add absolute capture time property to rtp sources.

This part of the effort to implement A/V sync metric.

Bug: webrtc:10739
Change-Id: I4adba1b99b37b31868168e37d9aa8e03f8ea6d4e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/159886
Commit-Queue: Ruslan Burakov <kuddai@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Minyue Li <minyue@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Ruslan Burakov <kuddai@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29849}
diff --git a/modules/rtp_rtcp/source/source_tracker.cc b/modules/rtp_rtcp/source/source_tracker.cc
index 2878b11..22b887c 100644
--- a/modules/rtp_rtcp/source/source_tracker.cc
+++ b/modules/rtp_rtcp/source/source_tracker.cc
@@ -34,6 +34,7 @@
 
       entry.timestamp_ms = now_ms;
       entry.audio_level = packet_info.audio_level();
+      entry.absolute_capture_time = packet_info.absolute_capture_time();
       entry.rtp_timestamp = packet_info.rtp_timestamp();
     }
 
@@ -42,6 +43,7 @@
 
     entry.timestamp_ms = now_ms;
     entry.audio_level = packet_info.audio_level();
+    entry.absolute_capture_time = packet_info.absolute_capture_time();
     entry.rtp_timestamp = packet_info.rtp_timestamp();
   }
 
@@ -60,8 +62,9 @@
     const SourceKey& key = pair.first;
     const SourceEntry& entry = pair.second;
 
-    sources.emplace_back(entry.timestamp_ms, key.source, key.source_type,
-                         entry.audio_level, entry.rtp_timestamp);
+    sources.emplace_back(
+        entry.timestamp_ms, key.source, key.source_type, entry.rtp_timestamp,
+        RtpSource::Extensions{entry.audio_level, entry.absolute_capture_time});
   }
 
   return sources;
diff --git a/modules/rtp_rtcp/source/source_tracker.h b/modules/rtp_rtcp/source/source_tracker.h
index 3ea16e9..fcf99bf 100644
--- a/modules/rtp_rtcp/source/source_tracker.h
+++ b/modules/rtp_rtcp/source/source_tracker.h
@@ -90,6 +90,11 @@
     // specs for `RTCRtpContributingSource` for more info.
     absl::optional<uint8_t> audio_level;
 
+    // Absolute capture time header extension received or interpolated from the
+    // most recent packet used to assemble the frame. For more info see
+    // https://webrtc.org/experiments/rtp-hdrext/abs-capture-time/
+    absl::optional<AbsoluteCaptureTime> absolute_capture_time;
+
     // RTP timestamp of the most recent packet used to assemble the frame
     // associated with |timestamp_ms|.
     uint32_t rtp_timestamp;
diff --git a/modules/rtp_rtcp/source/source_tracker_unittest.cc b/modules/rtp_rtcp/source/source_tracker_unittest.cc
index 8f6a512..32f9f4b 100644
--- a/modules/rtp_rtcp/source/source_tracker_unittest.cc
+++ b/modules/rtp_rtcp/source/source_tracker_unittest.cc
@@ -18,6 +18,7 @@
 #include <utility>
 #include <vector>
 
+#include "absl/types/optional.h"
 #include "api/rtp_headers.h"
 #include "api/rtp_packet_info.h"
 #include "api/rtp_packet_infos.h"
@@ -46,15 +47,16 @@
     const int64_t now_ms = clock_->TimeInMilliseconds();
 
     for (const auto& packet_info : packet_infos) {
+      RtpSource::Extensions extensions = {packet_info.audio_level(),
+                                          packet_info.absolute_capture_time()};
+
       for (const auto& csrc : packet_info.csrcs()) {
         entries_.emplace_front(now_ms, csrc, RtpSourceType::CSRC,
-                               packet_info.audio_level(),
-                               packet_info.rtp_timestamp());
+                               packet_info.rtp_timestamp(), extensions);
       }
 
       entries_.emplace_front(now_ms, packet_info.ssrc(), RtpSourceType::SSRC,
-                             packet_info.audio_level(),
-                             packet_info.rtp_timestamp());
+                             packet_info.rtp_timestamp(), extensions);
     }
 
     PruneEntries(now_ms);
@@ -243,7 +245,9 @@
   constexpr uint32_t kCsrcs1 = 21;
   constexpr uint32_t kRtpTimestamp = 40;
   constexpr absl::optional<uint8_t> kAudioLevel = 50;
-  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime = {};
+  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime =
+      AbsoluteCaptureTime{/*absolute_capture_timestamp=*/12,
+                          /*estimated_capture_clock_offset=*/absl::nullopt};
   constexpr int64_t kReceiveTimeMs = 60;
 
   SimulatedClock clock(1000000000000ULL);
@@ -254,14 +258,16 @@
                      kAbsoluteCaptureTime, kReceiveTimeMs)}));
 
   int64_t timestamp_ms = clock.TimeInMilliseconds();
+  constexpr RtpSource::Extensions extensions = {kAudioLevel,
+                                                kAbsoluteCaptureTime};
 
   EXPECT_THAT(tracker.GetSources(),
               ElementsAre(RtpSource(timestamp_ms, kSsrc, RtpSourceType::SSRC,
-                                    kAudioLevel, kRtpTimestamp),
+                                    kRtpTimestamp, extensions),
                           RtpSource(timestamp_ms, kCsrcs1, RtpSourceType::CSRC,
-                                    kAudioLevel, kRtpTimestamp),
+                                    kRtpTimestamp, extensions),
                           RtpSource(timestamp_ms, kCsrcs0, RtpSourceType::CSRC,
-                                    kAudioLevel, kRtpTimestamp)));
+                                    kRtpTimestamp, extensions)));
 }
 
 TEST(SourceTrackerTest, OnFrameDeliveredUpdatesSources) {
@@ -273,7 +279,10 @@
   constexpr uint32_t kRtpTimestamp1 = 41;
   constexpr absl::optional<uint8_t> kAudioLevel0 = 50;
   constexpr absl::optional<uint8_t> kAudioLevel1 = absl::nullopt;
-  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime = {};
+  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime0 =
+      AbsoluteCaptureTime{12, 34};
+  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime1 =
+      AbsoluteCaptureTime{56, 78};
   constexpr int64_t kReceiveTimeMs0 = 60;
   constexpr int64_t kReceiveTimeMs1 = 61;
 
@@ -282,7 +291,7 @@
 
   tracker.OnFrameDelivered(RtpPacketInfos(
       {RtpPacketInfo(kSsrc, {kCsrcs0, kCsrcs1}, kRtpTimestamp0, kAudioLevel0,
-                     kAbsoluteCaptureTime, kReceiveTimeMs0)}));
+                     kAbsoluteCaptureTime0, kReceiveTimeMs0)}));
 
   int64_t timestamp_ms_0 = clock.TimeInMilliseconds();
 
@@ -290,20 +299,25 @@
 
   tracker.OnFrameDelivered(RtpPacketInfos(
       {RtpPacketInfo(kSsrc, {kCsrcs0, kCsrcs2}, kRtpTimestamp1, kAudioLevel1,
-                     kAbsoluteCaptureTime, kReceiveTimeMs1)}));
+                     kAbsoluteCaptureTime1, kReceiveTimeMs1)}));
 
   int64_t timestamp_ms_1 = clock.TimeInMilliseconds();
 
+  constexpr RtpSource::Extensions extensions0 = {kAudioLevel0,
+                                                 kAbsoluteCaptureTime0};
+  constexpr RtpSource::Extensions extensions1 = {kAudioLevel1,
+                                                 kAbsoluteCaptureTime1};
+
   EXPECT_THAT(
       tracker.GetSources(),
       ElementsAre(RtpSource(timestamp_ms_1, kSsrc, RtpSourceType::SSRC,
-                            kAudioLevel1, kRtpTimestamp1),
+                            kRtpTimestamp1, extensions1),
                   RtpSource(timestamp_ms_1, kCsrcs2, RtpSourceType::CSRC,
-                            kAudioLevel1, kRtpTimestamp1),
+                            kRtpTimestamp1, extensions1),
                   RtpSource(timestamp_ms_1, kCsrcs0, RtpSourceType::CSRC,
-                            kAudioLevel1, kRtpTimestamp1),
+                            kRtpTimestamp1, extensions1),
                   RtpSource(timestamp_ms_0, kCsrcs1, RtpSourceType::CSRC,
-                            kAudioLevel0, kRtpTimestamp0)));
+                            kRtpTimestamp0, extensions0)));
 }
 
 TEST(SourceTrackerTest, TimedOutSourcesAreRemoved) {
@@ -315,7 +329,10 @@
   constexpr uint32_t kRtpTimestamp1 = 41;
   constexpr absl::optional<uint8_t> kAudioLevel0 = 50;
   constexpr absl::optional<uint8_t> kAudioLevel1 = absl::nullopt;
-  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime = {};
+  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime0 =
+      AbsoluteCaptureTime{12, 34};
+  constexpr absl::optional<AbsoluteCaptureTime> kAbsoluteCaptureTime1 =
+      AbsoluteCaptureTime{56, 78};
   constexpr int64_t kReceiveTimeMs0 = 60;
   constexpr int64_t kReceiveTimeMs1 = 61;
 
@@ -324,26 +341,29 @@
 
   tracker.OnFrameDelivered(RtpPacketInfos(
       {RtpPacketInfo(kSsrc, {kCsrcs0, kCsrcs1}, kRtpTimestamp0, kAudioLevel0,
-                     kAbsoluteCaptureTime, kReceiveTimeMs0)}));
+                     kAbsoluteCaptureTime0, kReceiveTimeMs0)}));
 
   clock.AdvanceTimeMilliseconds(17);
 
   tracker.OnFrameDelivered(RtpPacketInfos(
       {RtpPacketInfo(kSsrc, {kCsrcs0, kCsrcs2}, kRtpTimestamp1, kAudioLevel1,
-                     kAbsoluteCaptureTime, kReceiveTimeMs1)}));
+                     kAbsoluteCaptureTime1, kReceiveTimeMs1)}));
 
   int64_t timestamp_ms_1 = clock.TimeInMilliseconds();
 
   clock.AdvanceTimeMilliseconds(SourceTracker::kTimeoutMs);
 
+  constexpr RtpSource::Extensions extensions1 = {kAudioLevel1,
+                                                 kAbsoluteCaptureTime1};
+
   EXPECT_THAT(
       tracker.GetSources(),
       ElementsAre(RtpSource(timestamp_ms_1, kSsrc, RtpSourceType::SSRC,
-                            kAudioLevel1, kRtpTimestamp1),
+                            kRtpTimestamp1, extensions1),
                   RtpSource(timestamp_ms_1, kCsrcs2, RtpSourceType::CSRC,
-                            kAudioLevel1, kRtpTimestamp1),
+                            kRtpTimestamp1, extensions1),
                   RtpSource(timestamp_ms_1, kCsrcs0, RtpSourceType::CSRC,
-                            kAudioLevel1, kRtpTimestamp1)));
+                            kRtpTimestamp1, extensions1)));
 }
 
 }  // namespace webrtc