Allow to change base minimum delay on NetEq.

This is first step to allow to set latency
from client code in Chromium.
Existing minimum latency hasn't been used because it can clash
with video syncronization code.

Bug: webrtc:10287
Change-Id: Ia38906506069a1abfa01698dc62df283fc15cfbc
Reviewed-on: https://webrtc-review.googlesource.com/c/121423
Reviewed-by: Ivo Creusen <ivoc@webrtc.org>
Commit-Queue: Ruslan Burakov <kuddai@google.com>
Cr-Commit-Position: refs/heads/master@{#26536}

modules/audio_coding/neteq/delay_manager.cc

@@ -482,16 +482,19 @@ DelayManager::IATVector DelayManager::ScaleHistogram(const IATVector& histogram,
   return new_histogram;
 }
 
+bool DelayManager::IsValidMinimumDelay(int delay_ms) {
+  const int q75 =
+      rtc::dchecked_cast<int>(3 * max_packets_in_buffer_ * packet_len_ms_ / 4);
+  return delay_ms >= 0 &&
+         (maximum_delay_ms_ <= 0 || delay_ms <= maximum_delay_ms_) &&
+         (packet_len_ms_ <= 0 || delay_ms <= q75);
+}
+
 bool DelayManager::SetMinimumDelay(int delay_ms) {
-  // Minimum delay shouldn't be more than maximum delay, if any maximum is set.
-  // Also, if possible check |delay| to less than 75% of
-  // |max_packets_in_buffer_|.
-  if ((maximum_delay_ms_ > 0 && delay_ms > maximum_delay_ms_) ||
-      (packet_len_ms_ > 0 &&
-       delay_ms >
-           static_cast<int>(3 * max_packets_in_buffer_ * packet_len_ms_ / 4))) {
+  if (!IsValidMinimumDelay(delay_ms)) {
     return false;
   }
+  // Ensure that minimum_delay_ms is no bigger than base_min_target_delay_ms_
   minimum_delay_ms_ = std::max(delay_ms, base_min_target_delay_ms_);
   return true;
 }
@@ -509,6 +512,21 @@ bool DelayManager::SetMaximumDelay(int delay_ms) {
   return true;
 }
 
+bool DelayManager::SetBaseMinimumDelay(int delay_ms) {
+  if (!IsValidMinimumDelay(delay_ms)) {
+    return false;
+  }
+
+  base_min_target_delay_ms_ = delay_ms;
+  // Ensure that minimum_delay_ms is no bigger than base_min_target_delay_ms_
+  minimum_delay_ms_ = std::max(delay_ms, base_min_target_delay_ms_);
+  return true;
+}
+
+int DelayManager::GetBaseMinimumDelay() const {
+  return base_min_target_delay_ms_;
+}
+
 int DelayManager::base_target_level() const {
   return base_target_level_;
 }

modules/audio_coding/neteq/delay_manager.h

@@ -112,6 +112,8 @@ class DelayManager {
   // Assuming |delay| is in valid range.
   virtual bool SetMinimumDelay(int delay_ms);
   virtual bool SetMaximumDelay(int delay_ms);
+  virtual bool SetBaseMinimumDelay(int delay_ms);
+  virtual int GetBaseMinimumDelay() const;
   virtual int base_target_level() const;
   virtual void set_streaming_mode(bool value);
   virtual int last_pack_cng_or_dtmf() const;
@@ -141,13 +143,18 @@ class DelayManager {
   // called by Update().
   void LimitTargetLevel();
 
+  // Makes sure that |delay_ms| is less than maximum delay, if any maximum
+  // is set. Also, if possible check |delay_ms| to be less than 75% of
+  // |max_packets_in_buffer_|.
+  bool IsValidMinimumDelay(int delay_ms);
+
   bool first_packet_received_;
   const size_t max_packets_in_buffer_;  // Capacity of the packet buffer.
   IATVector iat_vector_;                // Histogram of inter-arrival times.
   int iat_factor_;  // Forgetting factor for updating the IAT histogram (Q15).
   const TickTimer* tick_timer_;
-  const int base_min_target_delay_ms_;  // Lower bound for target_level_ and
-                                        // minimum_delay_ms_.
+  int base_min_target_delay_ms_;  // Lower bound for target_level_ and
+                                  // minimum_delay_ms_.
   // Time elapsed since last packet.
   std::unique_ptr<TickTimer::Stopwatch> packet_iat_stopwatch_;
   int base_target_level_;  // Currently preferred buffer level before peak

modules/audio_coding/neteq/delay_manager_unittest.cc

@@ -267,6 +267,50 @@ TEST_F(DelayManagerTest, MinDelay) {
   EXPECT_EQ(kMinDelayPackets << 8, dm_->TargetLevel());
 }
 
+TEST_F(DelayManagerTest, BaseMinDelay) {
+  const int kExpectedTarget = 5;
+  const int kTimeIncrement = kExpectedTarget * kFrameSizeMs;
+  SetPacketAudioLength(kFrameSizeMs);
+  // First packet arrival.
+  InsertNextPacket();
+  // Second packet arrival.
+  // Expect detector update method to be called once with inter-arrival time
+  // equal to |kExpectedTarget| packet. Return true to indicate peaks found.
+  EXPECT_CALL(detector_, Update(kExpectedTarget, false, _))
+      .WillRepeatedly(Return(true));
+  EXPECT_CALL(detector_, MaxPeakHeight())
+      .WillRepeatedly(Return(kExpectedTarget));
+  IncreaseTime(kTimeIncrement);
+  InsertNextPacket();
+
+  // No limit is applied.
+  EXPECT_EQ(kExpectedTarget << 8, dm_->TargetLevel());
+
+  int kBaseMinDelayPackets = kExpectedTarget + 2;
+  int kBaseMinDelayMs = kBaseMinDelayPackets * kFrameSizeMs;
+  EXPECT_TRUE(dm_->SetBaseMinimumDelay(kBaseMinDelayMs));
+  EXPECT_EQ(dm_->GetBaseMinimumDelay(), kBaseMinDelayMs);
+
+  IncreaseTime(kTimeIncrement);
+  InsertNextPacket();
+  EXPECT_EQ(dm_->GetBaseMinimumDelay(), kBaseMinDelayMs);
+  EXPECT_EQ(kBaseMinDelayPackets << 8, dm_->TargetLevel());
+}
+
+TEST_F(DelayManagerTest, BaseMinDelayGreaterThanMaxDelayIsInvalid) {
+  int kMaxDelayMs = 2 * kFrameSizeMs;
+  int kBaseMinDelayMs = 4 * kFrameSizeMs;
+  EXPECT_TRUE(dm_->SetMaximumDelay(kMaxDelayMs));
+  EXPECT_FALSE(dm_->SetBaseMinimumDelay(kBaseMinDelayMs));
+}
+
+TEST_F(DelayManagerTest, BaseMinDelayGreaterThanQ75MaxPacketsIsInvalid) {
+  // .75 of |max_packets_in_buffer|, + 1 to ensure that |kBaseMinDelayMs| is
+  // greater.
+  int kBaseMinDelayMs = (3 * kMaxNumberOfPackets * kFrameSizeMs / 4) + 1;
+  EXPECT_FALSE(dm_->SetBaseMinimumDelay(kBaseMinDelayMs));
+}
+
 TEST_F(DelayManagerTest, UpdateReorderedPacket) {
   SetPacketAudioLength(kFrameSizeMs);
   InsertNextPacket();