Revert "Change buffer level filter to store current level in number of samples."

This reverts commit 87977dd06e702ed517f26235c12e37bd927527c7.

Reason for revert: Breaks downstream project

Original change's description:
> Change buffer level filter to store current level in number of samples.
> 
> The buffer level should not be converted back and forth between samples and packets in case of variable packet lengths.
> 
> Bug: webrtc:10736
> Change-Id: Ia08dcfac3d8104dc79fbad0704a5f6f12a050a01
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/142178
> Reviewed-by: Minyue Li <minyue@webrtc.org>
> Commit-Queue: Jakob Ivarsson <jakobi@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#28368}

TBR=henrik.lundin@webrtc.org,minyue@webrtc.org,jakobi@webrtc.org

Change-Id: I3900c9f6071fce51d13fb3b7c886157304d7a5c3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:10736
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/143786
Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org>
Commit-Queue: Jakob Ivarsson <jakobi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28369}
diff --git a/modules/audio_coding/acm2/audio_coding_module_unittest.cc b/modules/audio_coding/acm2/audio_coding_module_unittest.cc
index f9488a3..c95091f 100644
--- a/modules/audio_coding/acm2/audio_coding_module_unittest.cc
+++ b/modules/audio_coding/acm2/audio_coding_module_unittest.cc
@@ -994,35 +994,35 @@
 #if (defined(WEBRTC_CODEC_ISAC) || defined(WEBRTC_CODEC_ISACFX)) && \
     defined(WEBRTC_CODEC_ILBC)
 TEST_F(AcmReceiverBitExactnessOldApi, 8kHzOutput) {
-  Run(8000, PlatformChecksum("bc5cc2391174c865f02d9b2ae568020a",
-                             "06621315b131e5ece54aff186ec7b9e4",
-                             "2d05bd35f4dd9798e4189d7da6e6ba10",
+  Run(8000, PlatformChecksum("bcfbe2e89b4317b22e29557168edf187",
+                             "af15addb648cf7f032d6415672365fb3",
+                             "54a0008eb79537dee1d8fdaa5bc29f4b",
                              "4598140b5e4f7ee66c5adad609e65a3e",
-                             "c0c14f9d8d4151510cafdaf78e2ebd20"));
+                             "3155d7f2593a3276986f36221a61783c"));
 }
 
 TEST_F(AcmReceiverBitExactnessOldApi, 16kHzOutput) {
-  Run(16000, PlatformChecksum("9e3893aeb5dda4f9cea6adec21d21ad8",
-                              "70d26c18385e05a35162460a2ef6a0e4",
-                              "b1ef73d7dde40033e30a76a1cc6a1ab6",
+  Run(16000, PlatformChecksum("1737deef193e6c90e139ce82b7361ae4",
+                              "9e2a9f7728c71d6559ce3a32d2b10a5d",
+                              "114958862099142ac78b12100c21cb8d",
                               "f2aad418af974a3b1694d5ae5cc2c3c7",
-                              "25ae85ea1d2d629956cec7ea0b94f51c"));
+                              "af2889a5ca84fb40c9aa209b9318ee7a"));
 }
 
 TEST_F(AcmReceiverBitExactnessOldApi, 32kHzOutput) {
-  Run(32000, PlatformChecksum("4be3e35ebfdce55157491945610ef663",
-                              "424fcd896d2050530648de083567aff7",
-                              "ab50b8546f56c359c8e4c7d74e49aae4",
+  Run(32000, PlatformChecksum("1bf40ff024c6aa5b832d1d242c29cb3b",
+                              "3c9690cd136e9ecd1b26a22f70fe1d5c",
+                              "a1a3a01d8e25fcd11f1cedcd02e968b8",
                               "100869c8dcde51346c2073e52a272d98",
-                              "87731746b160e4ae8313fa8af92bba12"));
+                              "33695077e9ec6bca80819ce2ba263a78"));
 }
 
 TEST_F(AcmReceiverBitExactnessOldApi, 48kHzOutput) {
-  Run(48000, PlatformChecksum("1df82e2f5c1c96d94ad0edc55c723d01",
-                              "a623e44f7e41263245361e2b8c6cedd2",
-                              "22d0e9c2b62f367fb2d2052569c70e55",
+  Run(48000, PlatformChecksum("bf92db1e502deff5adf6fd2e6ab9a2e5",
+                              "c37b110ab50d87620972daee5d1eaf31",
+                              "5d55b68be7bcf39b60fcc74519363fb4",
                               "bd44bf97e7899186532f91235cef444d",
-                              "c3188d9fdaa8057a98815c9b7ecc48f1"));
+                              "32eec738698ffe62b9777d6a349cd596"));
 }
 
 TEST_F(AcmReceiverBitExactnessOldApi, 48kHzOutputExternalDecoder) {
@@ -1105,11 +1105,11 @@
   rtc::scoped_refptr<rtc::RefCountedObject<ADFactory>> factory(
       new rtc::RefCountedObject<ADFactory>);
   Run(48000,
-      PlatformChecksum("1df82e2f5c1c96d94ad0edc55c723d01",
-                       "a623e44f7e41263245361e2b8c6cedd2",
-                       "22d0e9c2b62f367fb2d2052569c70e55",
+      PlatformChecksum("bf92db1e502deff5adf6fd2e6ab9a2e5",
+                       "c37b110ab50d87620972daee5d1eaf31",
+                       "5d55b68be7bcf39b60fcc74519363fb4",
                        "bd44bf97e7899186532f91235cef444d",
-                       "c3188d9fdaa8057a98815c9b7ecc48f1"),
+                       "32eec738698ffe62b9777d6a349cd596"),
       factory, [](AudioCodingModule* acm) {
         acm->SetReceiveCodecs({{0, {"MockPCMu", 8000, 1}},
                                {103, {"ISAC", 16000, 1}},
@@ -1328,7 +1328,7 @@
   Run(AcmReceiverBitExactnessOldApi::PlatformChecksum(
           "2c9cb15d4ed55b5a0cadd04883bc73b0",
           "9336a9b993cbd8a751f0e8958e66c89c",
-          "5c2eb46199994506236f68b2c8e51b0d",
+          "bd4682225f7c4ad5f2049f6769713ac2",
           "343f1f42be0607c61e6516aece424609",
           "2c9cb15d4ed55b5a0cadd04883bc73b0"),
       AcmReceiverBitExactnessOldApi::PlatformChecksum(
@@ -1343,11 +1343,11 @@
 TEST_F(AcmSenderBitExactnessOldApi, IsacWb60ms) {
   ASSERT_NO_FATAL_FAILURE(SetUpTest("ISAC", 16000, 1, 103, 960, 960));
   Run(AcmReceiverBitExactnessOldApi::PlatformChecksum(
-          "f59760fa000991ee5fa81f2e607db254",
-          "986aa16d7097a26e32e212e39ec58517",
-          "9a81e467eb1485f84aca796f8ea65011",
+          "1ad29139a04782a33daad8c2b9b35875",
+          "14d63c5f08127d280e722e3191b73bdd",
+          "edcf26694c289e3d9691faf79b74f09f",
           "ef75e900e6f375e3061163c53fd09a63",
-          "f59760fa000991ee5fa81f2e607db254"),
+          "1ad29139a04782a33daad8c2b9b35875"),
       AcmReceiverBitExactnessOldApi::PlatformChecksum(
           "9e0a0ab743ad987b55b8e14802769c56",
           "ebe04a819d3a9d83a83a17f271e1139a",
diff --git a/modules/audio_coding/neteq/buffer_level_filter.cc b/modules/audio_coding/neteq/buffer_level_filter.cc
index 675091d..2f96618 100644
--- a/modules/audio_coding/neteq/buffer_level_filter.cc
+++ b/modules/audio_coding/neteq/buffer_level_filter.cc
@@ -22,31 +22,52 @@
 }
 
 void BufferLevelFilter::Reset() {
-  filtered_current_level_ = 0.0;
-  level_factor_ = 0.988;
+  filtered_current_level_ = 0;
+  level_factor_ = 253;
 }
 
-void BufferLevelFilter::Update(size_t buffer_size_samples,
-                               int time_stretched_samples) {
-  filtered_current_level_ = level_factor_ * filtered_current_level_ +
-                            (1 - level_factor_) * buffer_size_samples;
-
-  // Account for time-scale operations (accelerate and pre-emptive expand) and
-  // make sure that the filtered value remains non-negative.
+void BufferLevelFilter::Update(size_t buffer_size_packets,
+                               int time_stretched_samples,
+                               size_t packet_len_samples) {
+  // Filter:
+  // |filtered_current_level_| = |level_factor_| * |filtered_current_level_| +
+  //                            (1 - |level_factor_|) * |buffer_size_packets|
+  // |level_factor_| and |filtered_current_level_| are in Q8.
+  // |buffer_size_packets| is in Q0.
   filtered_current_level_ =
-      std::max(0.0, filtered_current_level_ - time_stretched_samples);
+      ((level_factor_ * filtered_current_level_) >> 8) +
+      ((256 - level_factor_) * rtc::dchecked_cast<int>(buffer_size_packets));
+
+  // Account for time-scale operations (accelerate and pre-emptive expand).
+  if (time_stretched_samples && packet_len_samples > 0) {
+    // Time-scaling has been performed since last filter update. Subtract the
+    // value of |time_stretched_samples| from |filtered_current_level_| after
+    // converting |time_stretched_samples| from samples to packets in Q8.
+    // Make sure that the filtered value remains non-negative.
+
+    int64_t time_stretched_packets =
+        (int64_t{time_stretched_samples} * (1 << 8)) /
+        rtc::dchecked_cast<int64_t>(packet_len_samples);
+
+    filtered_current_level_ = rtc::saturated_cast<int>(
+        std::max<int64_t>(0, filtered_current_level_ - time_stretched_packets));
+  }
 }
 
-void BufferLevelFilter::SetTargetBufferLevel(int target_buffer_level_packets) {
-  if (target_buffer_level_packets <= 1) {
-    level_factor_ = 0.980;
-  } else if (target_buffer_level_packets <= 3) {
-    level_factor_ = 0.984;
-  } else if (target_buffer_level_packets <= 7) {
-    level_factor_ = 0.988;
+void BufferLevelFilter::SetTargetBufferLevel(int target_buffer_level) {
+  if (target_buffer_level <= 1) {
+    level_factor_ = 251;
+  } else if (target_buffer_level <= 3) {
+    level_factor_ = 252;
+  } else if (target_buffer_level <= 7) {
+    level_factor_ = 253;
   } else {
-    level_factor_ = 0.992;
+    level_factor_ = 254;
   }
 }
 
+int BufferLevelFilter::filtered_current_level() const {
+  return filtered_current_level_;
+}
+
 }  // namespace webrtc
diff --git a/modules/audio_coding/neteq/buffer_level_filter.h b/modules/audio_coding/neteq/buffer_level_filter.h
index 18b43a3..83388fb 100644
--- a/modules/audio_coding/neteq/buffer_level_filter.h
+++ b/modules/audio_coding/neteq/buffer_level_filter.h
@@ -24,24 +24,24 @@
   virtual void Reset();
 
   // Updates the filter. Current buffer size is |buffer_size_packets| (Q0).
-  // |time_stretched_samples| is subtracted from the filtered value (thus
-  // bypassing the filter operation).
-  virtual void Update(size_t buffer_size_samples, int time_stretched_samples);
+  // If |time_stretched_samples| is non-zero, the value is converted to the
+  // corresponding number of packets, and is subtracted from the filtered
+  // value (thus bypassing the filter operation). |packet_len_samples| is the
+  // number of audio samples carried in each incoming packet.
+  virtual void Update(size_t buffer_size_packets,
+                      int time_stretched_samples,
+                      size_t packet_len_samples);
 
-  // Set the current target buffer level in number of packets (obtained from
+  // Set the current target buffer level (obtained from
   // DelayManager::base_target_level()). Used to select the appropriate
   // filter coefficient.
-  virtual void SetTargetBufferLevel(int target_buffer_level_packets);
+  virtual void SetTargetBufferLevel(int target_buffer_level);
 
-  // Returns filtered current level in number of samples.
-  virtual int filtered_current_level() const {
-    // Round to nearest whole sample.
-    return static_cast<int>(filtered_current_level_ + 0.5);
-  }
+  virtual int filtered_current_level() const;
 
  private:
-  double level_factor_;  // Filter factor for the buffer level filter.
-  double filtered_current_level_;
+  int level_factor_;  // Filter factor for the buffer level filter in Q8.
+  int filtered_current_level_;  // Filtered current buffer level in Q8.
 
   RTC_DISALLOW_COPY_AND_ASSIGN(BufferLevelFilter);
 };
diff --git a/modules/audio_coding/neteq/buffer_level_filter_unittest.cc b/modules/audio_coding/neteq/buffer_level_filter_unittest.cc
index 0d4a0f2..1f12e73 100644
--- a/modules/audio_coding/neteq/buffer_level_filter_unittest.cc
+++ b/modules/audio_coding/neteq/buffer_level_filter_unittest.cc
@@ -30,22 +30,23 @@
   for (int times = 10; times <= 50; times += 10) {
     for (int value = 100; value <= 200; value += 10) {
       filter.Reset();
-      filter.SetTargetBufferLevel(1);  // Makes filter coefficient 0.98.
+      filter.SetTargetBufferLevel(1);  // Makes filter coefficient 251/256.
       rtc::StringBuilder ss;
       ss << "times = " << times << ", value = " << value;
       SCOPED_TRACE(ss.str());  // Print out the parameter values on failure.
       for (int i = 0; i < times; ++i) {
-        filter.Update(value, 0 /* time_stretched_samples */);
+        filter.Update(value, 0 /* time_stretched_samples */,
+                      160 /* packet_len_samples */);
       }
       // Expect the filtered value to be (theoretically)
-      // (1 - 0.980 ^ |times|) * |value|.
-      double expected_value_double = (1 - pow(0.98, times)) * value;
+      // (1 - (251/256) ^ |times|) * |value|.
+      double expected_value_double = (1 - pow(251.0 / 256.0, times)) * value;
       int expected_value = static_cast<int>(expected_value_double);
       // filtered_current_level() returns the value in Q8.
       // The actual value may differ slightly from the expected value due to
       // intermediate-stage rounding errors in the filter implementation.
       // This is why we have to use EXPECT_NEAR with a tolerance of +/-1.
-      EXPECT_NEAR(expected_value, filter.filtered_current_level(), 1);
+      EXPECT_NEAR(expected_value, filter.filtered_current_level() >> 8, 1);
     }
   }
 }
@@ -57,60 +58,104 @@
   const int kTimes = 10;
   const int kValue = 100;
 
-  filter.SetTargetBufferLevel(3);  // Makes filter coefficient 0.984.
+  filter.SetTargetBufferLevel(3);  // Makes filter coefficient 252/256.
   for (int i = 0; i < kTimes; ++i) {
-    filter.Update(kValue, 0 /* time_stretched_samples */);
+    filter.Update(kValue, 0 /* time_stretched_samples */,
+                  160 /* packet_len_samples */);
   }
   // Expect the filtered value to be
-  // (1 - 0.984 ^ |kTimes|) * |kValue|.
-  int expected_value = 15;
-  EXPECT_EQ(expected_value, filter.filtered_current_level());
+  // (1 - (252/256) ^ |kTimes|) * |kValue|.
+  int expected_value = 14;
+  // filtered_current_level() returns the value in Q8.
+  EXPECT_EQ(expected_value, filter.filtered_current_level() >> 8);
 
   filter.Reset();
-  filter.SetTargetBufferLevel(7);  // Makes filter coefficient 0.988.
+  filter.SetTargetBufferLevel(7);  // Makes filter coefficient 253/256.
   for (int i = 0; i < kTimes; ++i) {
-    filter.Update(kValue, 0 /* time_stretched_samples */);
+    filter.Update(kValue, 0 /* time_stretched_samples */,
+                  160 /* packet_len_samples */);
   }
   // Expect the filtered value to be
-  // (1 - 0.988 ^ |kTimes|) * |kValue|.
+  // (1 - (253/256) ^ |kTimes|) * |kValue|.
   expected_value = 11;
-  EXPECT_EQ(expected_value, filter.filtered_current_level());
+  // filtered_current_level() returns the value in Q8.
+  EXPECT_EQ(expected_value, filter.filtered_current_level() >> 8);
 
   filter.Reset();
-  filter.SetTargetBufferLevel(8);  // Makes filter coefficient 0.992.
+  filter.SetTargetBufferLevel(8);  // Makes filter coefficient 254/256.
   for (int i = 0; i < kTimes; ++i) {
-    filter.Update(kValue, 0 /* time_stretched_samples */);
+    filter.Update(kValue, 0 /* time_stretched_samples */,
+                  160 /* packet_len_samples */);
   }
   // Expect the filtered value to be
-  // (1 - 0.992 ^ |kTimes|) * |kValue|.
-  expected_value = 8;
-  EXPECT_EQ(expected_value, filter.filtered_current_level());
+  // (1 - (254/256) ^ |kTimes|) * |kValue|.
+  expected_value = 7;
+  // filtered_current_level() returns the value in Q8.
+  EXPECT_EQ(expected_value, filter.filtered_current_level() >> 8);
 }
 
 TEST(BufferLevelFilter, TimeStretchedSamples) {
   BufferLevelFilter filter;
-  filter.SetTargetBufferLevel(1);  // Makes filter coefficient 0.98.
+  filter.SetTargetBufferLevel(1);  // Makes filter coefficient 251/256.
   // Update 10 times with value 100.
   const int kTimes = 10;
   const int kValue = 100;
-  const int kTimeStretchedSamples = 3;
+  const int kPacketSizeSamples = 160;
+  const int kNumPacketsStretched = 2;
+  const int kTimeStretchedSamples = kNumPacketsStretched * kPacketSizeSamples;
   for (int i = 0; i < kTimes; ++i) {
-    filter.Update(kValue, 0);
+    // Packet size set to 0. Do not expect the parameter
+    // |kTimeStretchedSamples| to have any effect.
+    filter.Update(kValue, kTimeStretchedSamples, 0 /* packet_len_samples */);
   }
   // Expect the filtered value to be
-  // (1 - 0.98 ^ |kTimes|) * |kValue|.
-  const int kExpectedValue = 18;
-  EXPECT_EQ(kExpectedValue, filter.filtered_current_level());
+  // (1 - (251/256) ^ |kTimes|) * |kValue|.
+  const int kExpectedValue = 17;
+  // filtered_current_level() returns the value in Q8.
+  EXPECT_EQ(kExpectedValue, filter.filtered_current_level() >> 8);
 
   // Update filter again, now with non-zero value for packet length.
   // Set the current filtered value to be the input, in order to isolate the
   // impact of |kTimeStretchedSamples|.
-  filter.Update(filter.filtered_current_level(), kTimeStretchedSamples);
-  EXPECT_EQ(kExpectedValue - kTimeStretchedSamples,
-            filter.filtered_current_level());
+  filter.Update(filter.filtered_current_level() >> 8, kTimeStretchedSamples,
+                kPacketSizeSamples);
+  EXPECT_EQ(kExpectedValue - kNumPacketsStretched,
+            filter.filtered_current_level() >> 8);
   // Try negative value and verify that we come back to the previous result.
-  filter.Update(filter.filtered_current_level(), -kTimeStretchedSamples);
-  EXPECT_EQ(kExpectedValue, filter.filtered_current_level());
+  filter.Update(filter.filtered_current_level() >> 8, -kTimeStretchedSamples,
+                kPacketSizeSamples);
+  EXPECT_EQ(kExpectedValue, filter.filtered_current_level() >> 8);
+}
+
+TEST(BufferLevelFilter, TimeStretchedSamplesNegativeUnevenFrames) {
+  BufferLevelFilter filter;
+  filter.SetTargetBufferLevel(1);  // Makes filter coefficient 251/256.
+  // Update 10 times with value 100.
+  const int kTimes = 10;
+  const int kValue = 100;
+  const int kPacketSizeSamples = 160;
+  const int kTimeStretchedSamples = -3.1415 * kPacketSizeSamples;
+  for (int i = 0; i < kTimes; ++i) {
+    // Packet size set to 0. Do not expect the parameter
+    // |kTimeStretchedSamples| to have any effect.
+    filter.Update(kValue, kTimeStretchedSamples, 0 /* packet_len_samples */);
+  }
+  // Expect the filtered value to be
+  // (1 - (251/256) ^ |kTimes|) * |kValue|.
+  const int kExpectedValue = 17;
+  // filtered_current_level() returns the value in Q8.
+  EXPECT_EQ(kExpectedValue, filter.filtered_current_level() >> 8);
+
+  // Update filter again, now with non-zero value for packet length.
+  // Set the current filtered value to be the input, in order to isolate the
+  // impact of |kTimeStretchedSamples|.
+  filter.Update(filter.filtered_current_level() >> 8, kTimeStretchedSamples,
+                kPacketSizeSamples);
+  EXPECT_EQ(21, filter.filtered_current_level() >> 8);
+  // Try negative value and verify that we come back to the previous result.
+  filter.Update(filter.filtered_current_level() >> 8, -kTimeStretchedSamples,
+                kPacketSizeSamples);
+  EXPECT_EQ(kExpectedValue, filter.filtered_current_level() >> 8);
 }
 
 }  // namespace webrtc
diff --git a/modules/audio_coding/neteq/decision_logic.cc b/modules/audio_coding/neteq/decision_logic.cc
index f9f420a..40e421d 100644
--- a/modules/audio_coding/neteq/decision_logic.cc
+++ b/modules/audio_coding/neteq/decision_logic.cc
@@ -113,9 +113,11 @@
     cng_state_ = kCngInternalOn;
   }
 
+  const size_t samples_left =
+      sync_buffer.FutureLength() - expand.overlap_length();
   // TODO(jakobi): Use buffer span instead of num samples.
   const size_t cur_size_samples =
-      packet_buffer_.NumSamplesInBuffer(decoder_frame_length);
+      samples_left + packet_buffer_.NumSamplesInBuffer(decoder_frame_length);
 
   prev_time_scale_ =
       prev_time_scale_ && (prev_mode == kModeAccelerateSuccess ||
@@ -173,7 +175,8 @@
   // if the mute factor is low enough (otherwise the expansion was short enough
   // to not be noticable).
   // Note that the MuteFactor is in Q14, so a value of 16384 corresponds to 1.
-  size_t current_span = packet_buffer_.GetSpanSamples(decoder_frame_length);
+  size_t current_span =
+      samples_left + packet_buffer_.GetSpanSamples(decoder_frame_length);
   if ((prev_mode == kModeExpand || prev_mode == kModeCodecPlc) &&
       expand.MuteFactor(0) < 16384 / 2 &&
       current_span < static_cast<size_t>(delay_manager_->TargetLevel() *
@@ -190,9 +193,9 @@
     return ExpectedPacketAvailable(prev_mode, play_dtmf);
   } else if (!PacketBuffer::IsObsoleteTimestamp(
                  available_timestamp, target_timestamp, five_seconds_samples)) {
-    return FuturePacketAvailable(decoder_frame_length, prev_mode,
-                                 target_timestamp, available_timestamp,
-                                 play_dtmf, generated_noise_samples);
+    return FuturePacketAvailable(
+        sync_buffer, expand, decoder_frame_length, prev_mode, target_timestamp,
+        available_timestamp, play_dtmf, generated_noise_samples);
   } else {
     // This implies that available_timestamp < target_timestamp, which can
     // happen when a new stream or codec is received. Signal for a reset.
@@ -212,13 +215,19 @@
   buffer_level_filter_->SetTargetBufferLevel(
       delay_manager_->base_target_level());
 
+  size_t buffer_size_packets = 0;
+  if (packet_length_samples_ > 0) {
+    // Calculate size in packets.
+    buffer_size_packets = buffer_size_samples / packet_length_samples_;
+  }
   int sample_memory_local = 0;
   if (prev_time_scale_) {
     sample_memory_local = sample_memory_;
     timescale_countdown_ = tick_timer_->GetNewCountdown(kMinTimescaleInterval);
   }
 
-  buffer_level_filter_->Update(buffer_size_samples, sample_memory_local);
+  buffer_level_filter_->Update(buffer_size_packets, sample_memory_local,
+                               packet_length_samples_);
   prev_time_scale_ = false;
 }
 
@@ -274,22 +283,15 @@
 Operations DecisionLogic::ExpectedPacketAvailable(Modes prev_mode,
                                                   bool play_dtmf) {
   if (!disallow_time_stretching_ && prev_mode != kModeExpand && !play_dtmf) {
-    // Check criterion for time-stretching. The values are in number of packets
-    // in Q8.
+    // Check criterion for time-stretching.
     int low_limit, high_limit;
     delay_manager_->BufferLimits(&low_limit, &high_limit);
-    int buffer_level_packets = 0;
-    if (packet_length_samples_ > 0) {
-      buffer_level_packets =
-          ((1 << 8) * buffer_level_filter_->filtered_current_level()) /
-          packet_length_samples_;
-    }
-    if (buffer_level_packets >= high_limit << 2)
+    if (buffer_level_filter_->filtered_current_level() >= high_limit << 2)
       return kFastAccelerate;
     if (TimescaleAllowed()) {
-      if (buffer_level_packets >= high_limit)
+      if (buffer_level_filter_->filtered_current_level() >= high_limit)
         return kAccelerate;
-      if (buffer_level_packets < low_limit)
+      if (buffer_level_filter_->filtered_current_level() < low_limit)
         return kPreemptiveExpand;
     }
   }
@@ -297,6 +299,8 @@
 }
 
 Operations DecisionLogic::FuturePacketAvailable(
+    const SyncBuffer& sync_buffer,
+    const Expand& expand,
     size_t decoder_frame_length,
     Modes prev_mode,
     uint32_t target_timestamp,
@@ -323,8 +327,10 @@
     return kNormal;
   }
 
+  const size_t samples_left =
+      sync_buffer.FutureLength() - expand.overlap_length();
   const size_t cur_size_samples =
-      packet_buffer_.NumPacketsInBuffer() * decoder_frame_length;
+      samples_left + packet_buffer_.NumPacketsInBuffer() * decoder_frame_length;
 
   // If previous was comfort noise, then no merge is needed.
   if (prev_mode == kModeRfc3389Cng || prev_mode == kModeCodecInternalCng) {
@@ -359,13 +365,8 @@
 }
 
 bool DecisionLogic::UnderTargetLevel() const {
-  int buffer_level_packets = 0;
-  if (packet_length_samples_ > 0) {
-    buffer_level_packets =
-        ((1 << 8) * buffer_level_filter_->filtered_current_level()) /
-        packet_length_samples_;
-  }
-  return buffer_level_packets <= delay_manager_->TargetLevel();
+  return buffer_level_filter_->filtered_current_level() <=
+         delay_manager_->TargetLevel();
 }
 
 bool DecisionLogic::ReinitAfterExpands(uint32_t timestamp_leap) const {
diff --git a/modules/audio_coding/neteq/decision_logic.h b/modules/audio_coding/neteq/decision_logic.h
index 49020b0..2414e8c 100644
--- a/modules/audio_coding/neteq/decision_logic.h
+++ b/modules/audio_coding/neteq/decision_logic.h
@@ -134,7 +134,9 @@
 
   // Returns the operation to do given that the expected packet is not
   // available, but a packet further into the future is at hand.
-  Operations FuturePacketAvailable(size_t decoder_frame_length,
+  Operations FuturePacketAvailable(const SyncBuffer& sync_buffer,
+                                   const Expand& expand,
+                                   size_t decoder_frame_length,
                                    Modes prev_mode,
                                    uint32_t target_timestamp,
                                    uint32_t available_timestamp,
diff --git a/modules/audio_coding/neteq/mock/mock_buffer_level_filter.h b/modules/audio_coding/neteq/mock/mock_buffer_level_filter.h
index 031195c..bf9fd59 100644
--- a/modules/audio_coding/neteq/mock/mock_buffer_level_filter.h
+++ b/modules/audio_coding/neteq/mock/mock_buffer_level_filter.h
@@ -22,8 +22,10 @@
   virtual ~MockBufferLevelFilter() { Die(); }
   MOCK_METHOD0(Die, void());
   MOCK_METHOD0(Reset, void());
-  MOCK_METHOD2(Update,
-               void(size_t buffer_size_samples, int time_stretched_samples));
+  MOCK_METHOD3(Update,
+               void(size_t buffer_size_packets,
+                    int time_stretched_samples,
+                    size_t packet_len_samples));
   MOCK_METHOD1(SetTargetBufferLevel, void(int target_buffer_level));
   MOCK_CONST_METHOD0(filtered_current_level, int());
 };
diff --git a/modules/audio_coding/neteq/neteq_impl.cc b/modules/audio_coding/neteq/neteq_impl.cc
index 82ec18d..ad6becc 100644
--- a/modules/audio_coding/neteq/neteq_impl.cc
+++ b/modules/audio_coding/neteq/neteq_impl.cc
@@ -310,12 +310,18 @@
 
 int NetEqImpl::FilteredCurrentDelayMs() const {
   rtc::CritScope lock(&crit_sect_);
+  // Calculate the filtered packet buffer level in samples. The value from
+  // |buffer_level_filter_| is in number of packets, represented in Q8.
+  const size_t packet_buffer_samples =
+      (buffer_level_filter_->filtered_current_level() *
+       decoder_frame_length_) >>
+      8;
   // Sum up the filtered packet buffer level with the future length of the sync
-  // buffer.
-  const int delay_samples = buffer_level_filter_->filtered_current_level() +
-                            sync_buffer_->FutureLength();
+  // buffer, and divide the sum by the sample rate.
+  const size_t delay_samples =
+      packet_buffer_samples + sync_buffer_->FutureLength();
   // The division below will truncate. The return value is in ms.
-  return delay_samples / rtc::CheckedDivExact(fs_hz_, 1000);
+  return static_cast<int>(delay_samples) / rtc::CheckedDivExact(fs_hz_, 1000);
 }
 
 int NetEqImpl::NetworkStatistics(NetEqNetworkStatistics* stats) {
diff --git a/modules/audio_coding/neteq/neteq_unittest.cc b/modules/audio_coding/neteq/neteq_unittest.cc
index a864985..6c67ca8 100644
--- a/modules/audio_coding/neteq/neteq_unittest.cc
+++ b/modules/audio_coding/neteq/neteq_unittest.cc
@@ -458,16 +458,16 @@
       webrtc::test::ResourcePath("audio_coding/neteq_universal_new", "rtp");
 
   const std::string output_checksum =
-      PlatformChecksum("415cc2366810676aad27a92b7a9068e79b7e4093",
-                       "52411c46e946e1d50fa777bbfb4686e7161f9cc7", "not used",
-                       "415cc2366810676aad27a92b7a9068e79b7e4093",
-                       "3e02f268f3b4f3acfcc1c397214ea13d09c212fd");
+      PlatformChecksum("9652cee1d6771a9cbfda821ae1bbdb41b0dd4dee",
+                       "54a7e32f163663c0af35bf70bf45cefc24ad62ef", "not used",
+                       "9652cee1d6771a9cbfda821ae1bbdb41b0dd4dee",
+                       "79496b0a1ef0a3824f3ee04789748a461bed643f");
 
   const std::string network_stats_checksum =
-      PlatformChecksum("6c8726e8699cc61535e65ef9406d339954a05cf8",
-                       "b9f2c862328ddb8d3ec9e79f61cc1d937ee56df6", "not used",
-                       "6c8726e8699cc61535e65ef9406d339954a05cf8",
-                       "6c8726e8699cc61535e65ef9406d339954a05cf8");
+      PlatformChecksum("c59b1f9f282b6d8733cdff975e3c150ca4a47d51",
+                       "bca95e565996a4ffd6e2ac15736e08843bdca93b", "not used",
+                       "c59b1f9f282b6d8733cdff975e3c150ca4a47d51",
+                       "c59b1f9f282b6d8733cdff975e3c150ca4a47d51");
 
   DecodeAndCompare(input_rtp_file, output_checksum, network_stats_checksum,
                    FLAG_gen_ref);
@@ -486,17 +486,17 @@
   // Checksum depends on libopus being compiled with or without SSE.
   const std::string maybe_sse =
       "14a63b3c7b925c82296be4bafc71bec85f2915c2|"
-      "8884ffe98700454875a88d1c3ea9b55e829a2016";
+      "2c05677daa968d6c68b92adf4affb7cd9bb4d363";
   const std::string output_checksum = PlatformChecksum(
-      maybe_sse, "1f76c884d16812704dec85f2b98db697108d2d9b",
-      "f888efef2d0710f202f19ba167ed509609146929", maybe_sse, maybe_sse);
+      maybe_sse, "b7b7ed802b0e18ee416973bf3b9ae98599b0181d",
+      "5876e52dda90d5ca433c3726555b907b97c86374", maybe_sse, maybe_sse);
 
   const std::string network_stats_checksum =
-      PlatformChecksum("bb8d91f71873df562224fe0dc5822b5dfb030090",
-                       "9f858290a675c4ceabf575feb6a59bef76d62eaf",
-                       "12963c965d9d102ebbc1f619508e2960a1f7dbee",
-                       "bb8d91f71873df562224fe0dc5822b5dfb030090",
-                       "bb8d91f71873df562224fe0dc5822b5dfb030090");
+      PlatformChecksum("adb3272498e436d1c019cbfd71610e9510c54497",
+                       "fa935a91abc7291db47428a2d7c5361b98713a92",
+                       "42106aa5267300f709f63737707ef07afd9dac61",
+                       "adb3272498e436d1c019cbfd71610e9510c54497",
+                       "adb3272498e436d1c019cbfd71610e9510c54497");
 
   DecodeAndCompare(input_rtp_file, output_checksum, network_stats_checksum,
                    FLAG_gen_ref);
@@ -796,7 +796,7 @@
   const double kDriftFactor = 1000.0 / (1000.0 + 25.0);
   const double kNetworkFreezeTimeMs = 5000.0;
   const bool kGetAudioDuringFreezeRecovery = false;
-  const int kDelayToleranceMs = 60;
+  const int kDelayToleranceMs = 50;
   const int kMaxTimeToSpeechMs = 200;
   LongCngWithClockDrift(kDriftFactor, kNetworkFreezeTimeMs,
                         kGetAudioDuringFreezeRecovery, kDelayToleranceMs,