From 766adcdeb845bf810045aca5cb987c056d0041e1 Mon Sep 17 00:00:00 2001
From: Jakob Ivarsson <jakobi@webrtc.org>
Date: Wed, 15 Mar 2023 22:40:33 +0100
Subject: [PATCH] Simplify NetEq CNG decision logic.
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This is in preparation of merging the PLC and CNG decision logic.

Bug: webrtc:13322
Change-Id: Ica782440b0d5c43c92ad5c33631b0cb708b51b0e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/297861
Commit-Queue: Jakob Ivarsson‎ <jakobi@webrtc.org>
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39580}
---
 modules/audio_coding/neteq/decision_logic.cc | 54 +++++++-------------
 1 file changed, 18 insertions(+), 36 deletions(-)

diff --git a/modules/audio_coding/neteq/decision_logic.cc b/modules/audio_coding/neteq/decision_logic.cc
index a52c3e9599..45402d9a83 100644
--- a/modules/audio_coding/neteq/decision_logic.cc
+++ b/modules/audio_coding/neteq/decision_logic.cc
@@ -378,51 +378,33 @@ NetEq::Operation DecisionLogic::FuturePacketAvailable(
   // Check if we should continue with an ongoing expand because the new packet
   // is too far into the future.
   if (IsExpand(status.last_mode) && ShouldContinueExpand(status)) {
-    if (status.play_dtmf) {
-      // Still have DTMF to play, so do not do expand.
-      return NetEq::Operation::kDtmf;
-    } else {
-      // Nothing to play.
-      return NetEq::Operation::kExpand;
-    }
+    return NoPacket(status);
   }
 
-  if (status.last_mode == NetEq::Mode::kCodecPlc) {
-    return NetEq::Operation::kNormal;
-  }
-
-  // If previous was comfort noise, then no merge is needed.
   if (IsCng(status.last_mode)) {
-    uint32_t timestamp_leap =
-        status.next_packet->timestamp - status.target_timestamp;
-    const bool generated_enough_noise =
-        status.generated_noise_samples >= timestamp_leap;
-
     int playout_delay_ms = GetNextPacketDelayMs(status);
     const bool above_target_delay = playout_delay_ms > HighThresholdCng();
     const bool below_target_delay = playout_delay_ms < LowThresholdCng();
-    // Keep the delay same as before CNG, but make sure that it is within the
-    // target window.
-    if ((generated_enough_noise && !below_target_delay) || above_target_delay) {
-      time_stretched_cn_samples_ =
-          timestamp_leap - status.generated_noise_samples;
-      return NetEq::Operation::kNormal;
+    if ((PacketTooEarly(status) && !above_target_delay) || below_target_delay) {
+      return NoPacket(status);
     }
-
-    if (status.last_mode == NetEq::Mode::kRfc3389Cng) {
-      return NetEq::Operation::kRfc3389CngNoPacket;
-    }
-    return NetEq::Operation::kCodecInternalCng;
+    uint32_t timestamp_leap =
+        status.next_packet->timestamp - status.target_timestamp;
+    time_stretched_cn_samples_ =
+        timestamp_leap - status.generated_noise_samples;
   }
 
-  // Do not merge unless we have done an expand before.
-  if (status.last_mode == NetEq::Mode::kExpand) {
-    return NetEq::Operation::kMerge;
-  } else if (status.play_dtmf) {
-    // Play DTMF instead of expand.
-    return NetEq::Operation::kDtmf;
-  } else {
-    return NetEq::Operation::kExpand;
+  // Time to play the next packet.
+  switch (status.last_mode) {
+    case NetEq::Mode::kExpand:
+      return NetEq::Operation::kMerge;
+    case NetEq::Mode::kCodecPlc:
+    case NetEq::Mode::kRfc3389Cng:
+    case NetEq::Mode::kCodecInternalCng:
+      return NetEq::Operation::kNormal;
+    default:
+      return status.play_dtmf ? NetEq::Operation::kDtmf
+                              : NetEq::Operation::kExpand;
   }
 }