From 7e937e951ca6273d524720efc59a651fd1a0adbe Mon Sep 17 00:00:00 2001
From: minyuel <minyue@webrtc.org>
Date: Mon, 29 Feb 2016 10:24:15 +0100
Subject: [PATCH] Remove workaround for Opus DTX noise pumping issue.

A workaround for Opus DTX noise pumping issue was made according upon this
https://codereview.webrtc.org/1422213003

Recently, Opus has fixed this problem internally, and hence the workaround is not needed any longer.

This CL removes this workaround.

BUG=586175
R=flim@webrtc.org, tina.legrand@webrtc.org

Review URL: https://codereview.webrtc.org/1715423002 .

Cr-Commit-Position: refs/heads/master@{#11805}
---
 .../audio_coding/codecs/opus/opus_inst.h      |  6 ---
 .../audio_coding/codecs/opus/opus_interface.c | 45 +------------------
 .../audio_coding/codecs/opus/opus_unittest.cc |  7 ++-
 3 files changed, 7 insertions(+), 51 deletions(-)

diff --git a/webrtc/modules/audio_coding/codecs/opus/opus_inst.h b/webrtc/modules/audio_coding/codecs/opus/opus_inst.h
index 8d032baf35..aa79b46f04 100644
--- a/webrtc/modules/audio_coding/codecs/opus/opus_inst.h
+++ b/webrtc/modules/audio_coding/codecs/opus/opus_inst.h
@@ -19,12 +19,6 @@ struct WebRtcOpusEncInst {
   OpusEncoder* encoder;
   size_t channels;
   int in_dtx_mode;
-  // When Opus is in DTX mode, we use |zero_counts| to count consecutive zeros
-  // to break long zero segment so as to prevent DTX from going wrong. We use
-  // one counter for each channel. After each encoding, |zero_counts| contain
-  // the remaining zeros from the last frame.
-  // TODO(minyue): remove this when Opus gets an internal fix to DTX.
-  size_t* zero_counts;
 };
 
 struct WebRtcOpusDecInst {
diff --git a/webrtc/modules/audio_coding/codecs/opus/opus_interface.c b/webrtc/modules/audio_coding/codecs/opus/opus_interface.c
index 9dc7ef95fe..bcb0596644 100644
--- a/webrtc/modules/audio_coding/codecs/opus/opus_interface.c
+++ b/webrtc/modules/audio_coding/codecs/opus/opus_interface.c
@@ -30,15 +30,6 @@ enum {
 
   /* Default frame size, 20 ms @ 48 kHz, in samples (for one channel). */
   kWebRtcOpusDefaultFrameSize = 960,
-
-  // Maximum number of consecutive zeros, beyond or equal to which DTX can fail.
-  kZeroBreakCount = 157,
-
-#if defined(OPUS_FIXED_POINT)
-  kZeroBreakValue = 10,
-#else
-  kZeroBreakValue = 1,
-#endif
 };
 
 int16_t WebRtcOpus_EncoderCreate(OpusEncInst** inst,
@@ -62,10 +53,6 @@ int16_t WebRtcOpus_EncoderCreate(OpusEncInst** inst,
   OpusEncInst* state = calloc(1, sizeof(OpusEncInst));
   assert(state);
 
-  // Allocate zero counters.
-  state->zero_counts = calloc(channels, sizeof(size_t));
-  assert(state->zero_counts);
-
   int error;
   state->encoder = opus_encoder_create(48000, (int)channels, opus_app,
                                        &error);
@@ -84,7 +71,6 @@ int16_t WebRtcOpus_EncoderCreate(OpusEncInst** inst,
 int16_t WebRtcOpus_EncoderFree(OpusEncInst* inst) {
   if (inst) {
     opus_encoder_destroy(inst->encoder);
-    free(inst->zero_counts);
     free(inst);
     return 0;
   } else {
@@ -98,42 +84,13 @@ int WebRtcOpus_Encode(OpusEncInst* inst,
                       size_t length_encoded_buffer,
                       uint8_t* encoded) {
   int res;
-  size_t i;
-  size_t c;
-
-  int16_t buffer[2 * 48 * kWebRtcOpusMaxEncodeFrameSizeMs];
 
   if (samples > 48 * kWebRtcOpusMaxEncodeFrameSizeMs) {
     return -1;
   }
 
-  const size_t channels = inst->channels;
-  int use_buffer = 0;
-
-  // Break long consecutive zeros by forcing a "1" every |kZeroBreakCount|
-  // samples.
-  if (inst->in_dtx_mode) {
-    for (i = 0; i < samples; ++i) {
-      for (c = 0; c < channels; ++c) {
-        if (audio_in[i * channels + c] == 0) {
-          ++inst->zero_counts[c];
-          if (inst->zero_counts[c] == kZeroBreakCount) {
-            if (!use_buffer) {
-              memcpy(buffer, audio_in, samples * channels * sizeof(int16_t));
-              use_buffer = 1;
-            }
-            buffer[i * channels + c] = kZeroBreakValue;
-            inst->zero_counts[c] = 0;
-          }
-        } else {
-          inst->zero_counts[c] = 0;
-        }
-      }
-    }
-  }
-
   res = opus_encode(inst->encoder,
-                    use_buffer ? buffer : audio_in,
+                    (const opus_int16*)audio_in,
                     (int)samples,
                     encoded,
                     (opus_int32)length_encoded_buffer);
diff --git a/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc b/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
index c33905a388..c634885e52 100644
--- a/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
+++ b/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
@@ -208,7 +208,12 @@ void OpusTest::TestDtxEffect(bool dtx, int block_length_ms) {
   const int kCheckTimeMs = 4000;
 
 #if defined(OPUS_FIXED_POINT)
-  const uint16_t kOutputValueBound = 20;
+  // Fixed-point Opus generates a random (comfort) noise, which has a less
+  // predictable value bound than its floating-point Opus. This value depends on
+  // input signal, and the time window for checking the output values (between
+  // |kCheckTimeMs| and |kRunTimeMs|).
+  const uint16_t kOutputValueBound = 30;
+
 #else
   const uint16_t kOutputValueBound = 2;
 #endif