From: Andreas Pehrson <apehrson@mozilla.com>
Date: Wed, 11 Jan 2023 22:42:00 +0000
Subject: Bug 1800942 - Add DCHECKs to
 TimestampExtrapolator::ExtrapolateLocalTime. r=mjf

Differential Revision: https://phabricator.services.mozilla.com/D166536
Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/c5df7f40392464ffc63f44a53ddcaab2091741e0
---
 modules/video_coding/timing/timestamp_extrapolator.cc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/modules/video_coding/timing/timestamp_extrapolator.cc b/modules/video_coding/timing/timestamp_extrapolator.cc
index c91aa1a362..dc62ac674a 100644
--- a/modules/video_coding/timing/timestamp_extrapolator.cc
+++ b/modules/video_coding/timing/timestamp_extrapolator.cc
@@ -125,6 +125,7 @@ void TimestampExtrapolator::Update(Timestamp now, uint32_t ts90khz) {
 absl::optional<Timestamp> TimestampExtrapolator::ExtrapolateLocalTime(
     uint32_t timestamp90khz) const {
   int64_t unwrapped_ts90khz = unwrapper_.PeekUnwrap(timestamp90khz);
+  RTC_DCHECK_GE(unwrapped_ts90khz, 0);
 
   if (!first_unwrapped_timestamp_) {
     return absl::nullopt;
@@ -132,12 +133,18 @@ absl::optional<Timestamp> TimestampExtrapolator::ExtrapolateLocalTime(
     constexpr double kRtpTicksPerMs = 90;
     TimeDelta diff = TimeDelta::Millis(
         (unwrapped_ts90khz - *prev_unwrapped_timestamp_) / kRtpTicksPerMs);
+    if (diff.ms() < 0) {
+      RTC_DCHECK_GE(prev_.ms(), -diff.ms());
+    }
     return prev_ + diff;
   } else if (w_[0] < 1e-3) {
     return start_;
   } else {
     double timestampDiff = unwrapped_ts90khz - *first_unwrapped_timestamp_;
     auto diff_ms = static_cast<int64_t>((timestampDiff - w_[1]) / w_[0] + 0.5);
+    if (diff_ms < 0) {
+      RTC_DCHECK_GE(start_.ms(), -diff_ms);
+    }
     return start_ + TimeDelta::Millis(diff_ms);
   }
 }
-- 
2.34.1