Move AudioCodingModuleImpl to anonymous namespace in audio_coding_module.cc

webrtc/modules/audio_coding/acm2/audio_coding_module.cc

Index: webrtc/modules/audio_coding/acm2/audio_coding_module.cc
diff --git a/webrtc/modules/audio_coding/acm2/audio_coding_module.cc b/webrtc/modules/audio_coding/acm2/audio_coding_module.cc
index 03064fbefbb9570b8c411a2f2f5749675bf9a04c..6170d187bab14ab53b62fe9795c6c56332040c0a 100644
--- a/webrtc/modules/audio_coding/acm2/audio_coding_module.cc
+++ b/webrtc/modules/audio_coding/acm2/audio_coding_module.cc
@@ -11,15 +11,1233 @@
 #include "webrtc/modules/audio_coding/include/audio_coding_module.h"
 
 #include "webrtc/base/checks.h"
-#include "webrtc/common_types.h"
-#include "webrtc/modules/audio_coding/acm2/audio_coding_module_impl.h"
+#include "webrtc/base/safe_conversions.h"
+#include "webrtc/modules/audio_coding/acm2/acm_receiver.h"
+#include "webrtc/modules/audio_coding/acm2/acm_resampler.h"
+#include "webrtc/modules/audio_coding/acm2/codec_manager.h"
 #include "webrtc/modules/audio_coding/acm2/rent_a_codec.h"
 #include "webrtc/modules/audio_coding/codecs/builtin_audio_decoder_factory.h"
-#include "webrtc/system_wrappers/include/clock.h"
+#include "webrtc/system_wrappers/include/metrics.h"
 #include "webrtc/system_wrappers/include/trace.h"
 
 namespace webrtc {
 
+namespace {
+
+struct EncoderFactory {
+  AudioEncoder* external_speech_encoder = nullptr;
+  acm2::CodecManager codec_manager;
+  acm2::RentACodec rent_a_codec;
+};
+
+class AudioCodingModuleImpl final : public AudioCodingModule {
+ public:
+  explicit AudioCodingModuleImpl(const AudioCodingModule::Config& config);
+  ~AudioCodingModuleImpl() override;
+
+  /////////////////////////////////////////
+  //   Sender
+  //
+
+  // Can be called multiple times for Codec, CNG, RED.
+  int RegisterSendCodec(const CodecInst& send_codec) override;
+
+  void RegisterExternalSendCodec(
+      AudioEncoder* external_speech_encoder) override;
+
+  void ModifyEncoder(
+      FunctionView<void(std::unique_ptr<AudioEncoder>*)> modifier) override;
+
+  // Get current send codec.
+  rtc::Optional<CodecInst> SendCodec() const override;
+
+  // Get current send frequency.
+  int SendFrequency() const override;
+
+  // Sets the bitrate to the specified value in bits/sec. In case the codec does
+  // not support the requested value it will choose an appropriate value
+  // instead.
+  void SetBitRate(int bitrate_bps) override;
+
+  // Register a transport callback which will be
+  // called to deliver the encoded buffers.
+  int RegisterTransportCallback(AudioPacketizationCallback* transport) override;
+
+  // Add 10 ms of raw (PCM) audio data to the encoder.
+  int Add10MsData(const AudioFrame& audio_frame) override;
+
+  /////////////////////////////////////////
+  // (RED) Redundant Coding
+  //
+
+  // Configure RED status i.e. on/off.
+  int SetREDStatus(bool enable_red) override;
+
+  // Get RED status.
+  bool REDStatus() const override;
+
+  /////////////////////////////////////////
+  // (FEC) Forward Error Correction (codec internal)
+  //
+
+  // Configure FEC status i.e. on/off.
+  int SetCodecFEC(bool enabled_codec_fec) override;
+
+  // Get FEC status.
+  bool CodecFEC() const override;
+
+  // Set target packet loss rate
+  int SetPacketLossRate(int loss_rate) override;
+
+  /////////////////////////////////////////
+  //   (VAD) Voice Activity Detection
+  //   and
+  //   (CNG) Comfort Noise Generation
+  //
+
+  int SetVAD(bool enable_dtx = true,
+             bool enable_vad = false,
+             ACMVADMode mode = VADNormal) override;
+
+  int VAD(bool* dtx_enabled,
+          bool* vad_enabled,
+          ACMVADMode* mode) const override;
+
+  int RegisterVADCallback(ACMVADCallback* vad_callback) override;
+
+  /////////////////////////////////////////
+  //   Receiver
+  //
+
+  // Initialize receiver, resets codec database etc.
+  int InitializeReceiver() override;
+
+  // Get current receive frequency.
+  int ReceiveFrequency() const override;
+
+  // Get current playout frequency.
+  int PlayoutFrequency() const override;
+
+  int RegisterReceiveCodec(const CodecInst& receive_codec) override;
+  int RegisterReceiveCodec(
+      const CodecInst& receive_codec,
+      FunctionView<std::unique_ptr<AudioDecoder>()> isac_factory) override;
+
+  int RegisterExternalReceiveCodec(int rtp_payload_type,
+                                   AudioDecoder* external_decoder,
+                                   int sample_rate_hz,
+                                   int num_channels,
+                                   const std::string& name) override;
+
+  // Get current received codec.
+  int ReceiveCodec(CodecInst* current_codec) const override;
+
+  // Incoming packet from network parsed and ready for decode.
+  int IncomingPacket(const uint8_t* incoming_payload,
+                     const size_t payload_length,
+                     const WebRtcRTPHeader& rtp_info) override;
+
+  // Incoming payloads, without rtp-info, the rtp-info will be created in ACM.
+  // One usage for this API is when pre-encoded files are pushed in ACM.
+  int IncomingPayload(const uint8_t* incoming_payload,
+                      const size_t payload_length,
+                      uint8_t payload_type,
+                      uint32_t timestamp) override;
+
+  // Minimum playout delay.
+  int SetMinimumPlayoutDelay(int time_ms) override;
+
+  // Maximum playout delay.
+  int SetMaximumPlayoutDelay(int time_ms) override;
+
+  // Smallest latency NetEq will maintain.
+  int LeastRequiredDelayMs() const override;
+
+  RTC_DEPRECATED int32_t PlayoutTimestamp(uint32_t* timestamp) override;
+
+  rtc::Optional<uint32_t> PlayoutTimestamp() override;
+
+  // Get 10 milliseconds of raw audio data to play out, and
+  // automatic resample to the requested frequency if > 0.
+  int PlayoutData10Ms(int desired_freq_hz,
+                      AudioFrame* audio_frame,
+                      bool* muted) override;
+  int PlayoutData10Ms(int desired_freq_hz, AudioFrame* audio_frame) override;
+
+  /////////////////////////////////////////
+  //   Statistics
+  //
+
+  int GetNetworkStatistics(NetworkStatistics* statistics) override;
+
+  int SetOpusApplication(OpusApplicationMode application) override;
+
+  // If current send codec is Opus, informs it about the maximum playback rate
+  // the receiver will render.
+  int SetOpusMaxPlaybackRate(int frequency_hz) override;
+
+  int EnableOpusDtx() override;
+
+  int DisableOpusDtx() override;
+
+  int UnregisterReceiveCodec(uint8_t payload_type) override;
+
+  int EnableNack(size_t max_nack_list_size) override;
+
+  void DisableNack() override;
+
+  std::vector<uint16_t> GetNackList(int64_t round_trip_time_ms) const override;
+
+  void GetDecodingCallStatistics(AudioDecodingCallStats* stats) const override;
+
+ private:
+  struct InputData {
+    uint32_t input_timestamp;
+    const int16_t* audio;
+    size_t length_per_channel;
+    size_t audio_channel;
+    // If a re-mix is required (up or down), this buffer will store a re-mixed
+    // version of the input.
+    int16_t buffer[WEBRTC_10MS_PCM_AUDIO];
+  };
+
+  // This member class writes values to the named UMA histogram, but only if
+  // the value has changed since the last time (and always for the first call).
+  class ChangeLogger {
+   public:
+    explicit ChangeLogger(const std::string& histogram_name)
+        : histogram_name_(histogram_name) {}
+    // Logs the new value if it is different from the last logged value, or if
+    // this is the first call.
+    void MaybeLog(int value);
+
+   private:
+    int last_value_ = 0;
+    int first_time_ = true;
+    const std::string histogram_name_;
+  };
+
+  int RegisterReceiveCodecUnlocked(
+      const CodecInst& codec,
+      FunctionView<std::unique_ptr<AudioDecoder>()> isac_factory)
+      EXCLUSIVE_LOCKS_REQUIRED(acm_crit_sect_);
+
+  int Add10MsDataInternal(const AudioFrame& audio_frame, InputData* input_data)
+      EXCLUSIVE_LOCKS_REQUIRED(acm_crit_sect_);
+  int Encode(const InputData& input_data)
+      EXCLUSIVE_LOCKS_REQUIRED(acm_crit_sect_);
+
+  int InitializeReceiverSafe() EXCLUSIVE_LOCKS_REQUIRED(acm_crit_sect_);
+
+  bool HaveValidEncoder(const char* caller_name) const
+      EXCLUSIVE_LOCKS_REQUIRED(acm_crit_sect_);
+
+  // Preprocessing of input audio, including resampling and down-mixing if
+  // required, before pushing audio into encoder's buffer.
+  //
+  // in_frame: input audio-frame
+  // ptr_out: pointer to output audio_frame. If no preprocessing is required
+  //          |ptr_out| will be pointing to |in_frame|, otherwise pointing to
+  //          |preprocess_frame_|.
+  //
+  // Return value:
+  //   -1: if encountering an error.
+  //    0: otherwise.
+  int PreprocessToAddData(const AudioFrame& in_frame,
+                          const AudioFrame** ptr_out)
+      EXCLUSIVE_LOCKS_REQUIRED(acm_crit_sect_);
+
+  // Change required states after starting to receive the codec corresponding
+  // to |index|.
+  int UpdateUponReceivingCodec(int index);
+
+  rtc::CriticalSection acm_crit_sect_;
+  rtc::Buffer encode_buffer_ GUARDED_BY(acm_crit_sect_);
+  int id_;  // TODO(henrik.lundin) Make const.
+  uint32_t expected_codec_ts_ GUARDED_BY(acm_crit_sect_);
+  uint32_t expected_in_ts_ GUARDED_BY(acm_crit_sect_);
+  acm2::ACMResampler resampler_ GUARDED_BY(acm_crit_sect_);
+  acm2::AcmReceiver receiver_;  // AcmReceiver has it's own internal lock.
+  ChangeLogger bitrate_logger_ GUARDED_BY(acm_crit_sect_);
+
+  std::unique_ptr<EncoderFactory> encoder_factory_ GUARDED_BY(acm_crit_sect_);
+
+  // Current encoder stack, either obtained from
+  // encoder_factory_->rent_a_codec.RentEncoderStack or provided by a call to
+  // RegisterEncoder.
+  std::unique_ptr<AudioEncoder> encoder_stack_ GUARDED_BY(acm_crit_sect_);
+
+  std::unique_ptr<AudioDecoder> isac_decoder_16k_ GUARDED_BY(acm_crit_sect_);
+  std::unique_ptr<AudioDecoder> isac_decoder_32k_ GUARDED_BY(acm_crit_sect_);
+
+  // This is to keep track of CN instances where we can send DTMFs.
+  uint8_t previous_pltype_ GUARDED_BY(acm_crit_sect_);
+
+  // Used when payloads are pushed into ACM without any RTP info
+  // One example is when pre-encoded bit-stream is pushed from
+  // a file.
+  // IMPORTANT: this variable is only used in IncomingPayload(), therefore,
+  // no lock acquired when interacting with this variable. If it is going to
+  // be used in other methods, locks need to be taken.
+  std::unique_ptr<WebRtcRTPHeader> aux_rtp_header_;
+
+  bool receiver_initialized_ GUARDED_BY(acm_crit_sect_);
+
+  AudioFrame preprocess_frame_ GUARDED_BY(acm_crit_sect_);
+  bool first_10ms_data_ GUARDED_BY(acm_crit_sect_);
+
+  bool first_frame_ GUARDED_BY(acm_crit_sect_);
+  uint32_t last_timestamp_ GUARDED_BY(acm_crit_sect_);
+  uint32_t last_rtp_timestamp_ GUARDED_BY(acm_crit_sect_);
+
+  rtc::CriticalSection callback_crit_sect_;
+  AudioPacketizationCallback* packetization_callback_
+      GUARDED_BY(callback_crit_sect_);
+  ACMVADCallback* vad_callback_ GUARDED_BY(callback_crit_sect_);
+
+  int codec_histogram_bins_log_[static_cast<size_t>(
+      AudioEncoder::CodecType::kMaxLoggedAudioCodecTypes)];
+  int number_of_consecutive_empty_packets_;
+};
+
+// Adds a codec usage sample to the histogram.
+void UpdateCodecTypeHistogram(size_t codec_type) {
+  RTC_HISTOGRAM_ENUMERATION(
+      "WebRTC.Audio.Encoder.CodecType", static_cast<int>(codec_type),
+      static_cast<int>(
+          webrtc::AudioEncoder::CodecType::kMaxLoggedAudioCodecTypes));
+}
+
+// TODO(turajs): the same functionality is used in NetEq. If both classes
+// need them, make it a static function in ACMCodecDB.
+bool IsCodecRED(const CodecInst& codec) {
+  return (STR_CASE_CMP(codec.plname, "RED") == 0);
+}
+
+bool IsCodecCN(const CodecInst& codec) {
+  return (STR_CASE_CMP(codec.plname, "CN") == 0);
+}
+
+// Stereo-to-mono can be used as in-place.
+int DownMix(const AudioFrame& frame,
+            size_t length_out_buff,
+            int16_t* out_buff) {
+  if (length_out_buff < frame.samples_per_channel_) {
+    return -1;
+  }
+  for (size_t n = 0; n < frame.samples_per_channel_; ++n)
+    out_buff[n] = (frame.data_[2 * n] + frame.data_[2 * n + 1]) >> 1;
+  return 0;
+}
+
+// Mono-to-stereo can be used as in-place.
+int UpMix(const AudioFrame& frame, size_t length_out_buff, int16_t* out_buff) {
+  if (length_out_buff < frame.samples_per_channel_) {
+    return -1;
+  }
+  for (size_t n = frame.samples_per_channel_; n != 0; --n) {
+    size_t i = n - 1;
+    int16_t sample = frame.data_[i];
+    out_buff[2 * i + 1] = sample;
+    out_buff[2 * i] = sample;
+  }
+  return 0;
+}
+
+void ConvertEncodedInfoToFragmentationHeader(
+    const AudioEncoder::EncodedInfo& info,
+    RTPFragmentationHeader* frag) {
+  if (info.redundant.empty()) {
+    frag->fragmentationVectorSize = 0;
+    return;
+  }
+
+  frag->VerifyAndAllocateFragmentationHeader(
+      static_cast<uint16_t>(info.redundant.size()));
+  frag->fragmentationVectorSize = static_cast<uint16_t>(info.redundant.size());
+  size_t offset = 0;
+  for (size_t i = 0; i < info.redundant.size(); ++i) {
+    frag->fragmentationOffset[i] = offset;
+    offset += info.redundant[i].encoded_bytes;
+    frag->fragmentationLength[i] = info.redundant[i].encoded_bytes;
+    frag->fragmentationTimeDiff[i] = rtc::checked_cast<uint16_t>(
+        info.encoded_timestamp - info.redundant[i].encoded_timestamp);
+    frag->fragmentationPlType[i] = info.redundant[i].payload_type;
+  }
+}
+
+// Wraps a raw AudioEncoder pointer. The idea is that you can put one of these
+// in a unique_ptr, to protect the contained raw pointer from being deleted
+// when the unique_ptr expires. (This is of course a bad idea in general, but
+// backwards compatibility.)
+class RawAudioEncoderWrapper final : public AudioEncoder {
+ public:
+  RawAudioEncoderWrapper(AudioEncoder* enc) : enc_(enc) {}
+  int SampleRateHz() const override { return enc_->SampleRateHz(); }
+  size_t NumChannels() const override { return enc_->NumChannels(); }
+  int RtpTimestampRateHz() const override { return enc_->RtpTimestampRateHz(); }
+  size_t Num10MsFramesInNextPacket() const override {
+    return enc_->Num10MsFramesInNextPacket();
+  }
+  size_t Max10MsFramesInAPacket() const override {
+    return enc_->Max10MsFramesInAPacket();
+  }
+  int GetTargetBitrate() const override { return enc_->GetTargetBitrate(); }
+  EncodedInfo EncodeImpl(uint32_t rtp_timestamp,
+                         rtc::ArrayView<const int16_t> audio,
+                         rtc::Buffer* encoded) override {
+    return enc_->Encode(rtp_timestamp, audio, encoded);
+  }
+  void Reset() override { return enc_->Reset(); }
+  bool SetFec(bool enable) override { return enc_->SetFec(enable); }
+  bool SetDtx(bool enable) override { return enc_->SetDtx(enable); }
+  bool SetApplication(Application application) override {
+    return enc_->SetApplication(application);
+  }
+  void SetMaxPlaybackRate(int frequency_hz) override {
+    return enc_->SetMaxPlaybackRate(frequency_hz);
+  }
+  void SetProjectedPacketLossRate(double fraction) override {
+    return enc_->SetProjectedPacketLossRate(fraction);
+  }
+  void SetTargetBitrate(int target_bps) override {
+    return enc_->SetTargetBitrate(target_bps);
+  }
+
+ private:
+  AudioEncoder* enc_;
+};
+
+// Return false on error.
+bool CreateSpeechEncoderIfNecessary(EncoderFactory* ef) {
+  auto* sp = ef->codec_manager.GetStackParams();
+  if (sp->speech_encoder) {
+    // Do nothing; we already have a speech encoder.
+  } else if (ef->codec_manager.GetCodecInst()) {
+    RTC_DCHECK(!ef->external_speech_encoder);
+    // We have no speech encoder, but we have a specification for making one.
+    std::unique_ptr<AudioEncoder> enc =
+        ef->rent_a_codec.RentEncoder(*ef->codec_manager.GetCodecInst());
+    if (!enc)
+      return false;  // Encoder spec was bad.
+    sp->speech_encoder = std::move(enc);
+  } else if (ef->external_speech_encoder) {
+    RTC_DCHECK(!ef->codec_manager.GetCodecInst());
+    // We have an external speech encoder.
+    sp->speech_encoder = std::unique_ptr<AudioEncoder>(
+        new RawAudioEncoderWrapper(ef->external_speech_encoder));
+  }
+  return true;
+}
+
+void AudioCodingModuleImpl::ChangeLogger::MaybeLog(int value) {
+  if (value != last_value_ || first_time_) {
+    first_time_ = false;
+    last_value_ = value;
+    RTC_HISTOGRAM_COUNTS_SPARSE_100(histogram_name_, value);
+  }
+}
+
+AudioCodingModuleImpl::AudioCodingModuleImpl(
+    const AudioCodingModule::Config& config)
+    : id_(config.id),
+      expected_codec_ts_(0xD87F3F9F),
+      expected_in_ts_(0xD87F3F9F),
+      receiver_(config),
+      bitrate_logger_("WebRTC.Audio.TargetBitrateInKbps"),
+      encoder_factory_(new EncoderFactory),
+      encoder_stack_(nullptr),
+      previous_pltype_(255),
+      receiver_initialized_(false),
+      first_10ms_data_(false),
+      first_frame_(true),
+      packetization_callback_(NULL),
+      vad_callback_(NULL),
+      codec_histogram_bins_log_(),
+      number_of_consecutive_empty_packets_(0) {
+  if (InitializeReceiverSafe() < 0) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Cannot initialize receiver");
+  }
+  WEBRTC_TRACE(webrtc::kTraceMemory, webrtc::kTraceAudioCoding, id_, "Created");
+}
+
+AudioCodingModuleImpl::~AudioCodingModuleImpl() = default;
+
+int32_t AudioCodingModuleImpl::Encode(const InputData& input_data) {
+  AudioEncoder::EncodedInfo encoded_info;
+  uint8_t previous_pltype;
+
+  // Check if there is an encoder before.
+  if (!HaveValidEncoder("Process"))
+    return -1;
+
+  // Scale the timestamp to the codec's RTP timestamp rate.
+  uint32_t rtp_timestamp =
+      first_frame_ ? input_data.input_timestamp
+                   : last_rtp_timestamp_ +
+                         rtc::CheckedDivExact(
+                             input_data.input_timestamp - last_timestamp_,
+                             static_cast<uint32_t>(rtc::CheckedDivExact(
+                                 encoder_stack_->SampleRateHz(),
+                                 encoder_stack_->RtpTimestampRateHz())));
+  last_timestamp_ = input_data.input_timestamp;
+  last_rtp_timestamp_ = rtp_timestamp;
+  first_frame_ = false;
+
+  // Clear the buffer before reuse - encoded data will get appended.
+  encode_buffer_.Clear();
+  encoded_info = encoder_stack_->Encode(
+      rtp_timestamp, rtc::ArrayView<const int16_t>(
+                         input_data.audio, input_data.audio_channel *
+                                               input_data.length_per_channel),
+      &encode_buffer_);
+
+  bitrate_logger_.MaybeLog(encoder_stack_->GetTargetBitrate() / 1000);
+  if (encode_buffer_.size() == 0 && !encoded_info.send_even_if_empty) {
+    // Not enough data.
+    return 0;
+  }
+  previous_pltype = previous_pltype_;  // Read it while we have the critsect.
+
+  // Log codec type to histogram once every 500 packets.
+  if (encoded_info.encoded_bytes == 0) {
+    ++number_of_consecutive_empty_packets_;
+  } else {
+    size_t codec_type = static_cast<size_t>(encoded_info.encoder_type);
+    codec_histogram_bins_log_[codec_type] +=
+        number_of_consecutive_empty_packets_ + 1;
+    number_of_consecutive_empty_packets_ = 0;
+    if (codec_histogram_bins_log_[codec_type] >= 500) {
+      codec_histogram_bins_log_[codec_type] -= 500;
+      UpdateCodecTypeHistogram(codec_type);
+    }
+  }
+
+  RTPFragmentationHeader my_fragmentation;
+  ConvertEncodedInfoToFragmentationHeader(encoded_info, &my_fragmentation);
+  FrameType frame_type;
+  if (encode_buffer_.size() == 0 && encoded_info.send_even_if_empty) {
+    frame_type = kEmptyFrame;
+    encoded_info.payload_type = previous_pltype;
+  } else {
+    RTC_DCHECK_GT(encode_buffer_.size(), 0u);
+    frame_type = encoded_info.speech ? kAudioFrameSpeech : kAudioFrameCN;
+  }
+
+  {
+    rtc::CritScope lock(&callback_crit_sect_);
+    if (packetization_callback_) {
+      packetization_callback_->SendData(
+          frame_type, encoded_info.payload_type, encoded_info.encoded_timestamp,
+          encode_buffer_.data(), encode_buffer_.size(),
+          my_fragmentation.fragmentationVectorSize > 0 ? &my_fragmentation
+                                                       : nullptr);
+    }
+
+    if (vad_callback_) {
+      // Callback with VAD decision.
+      vad_callback_->InFrameType(frame_type);
+    }
+  }
+  previous_pltype_ = encoded_info.payload_type;
+  return static_cast<int32_t>(encode_buffer_.size());
+}
+
+/////////////////////////////////////////
+//   Sender
+//
+
+// Can be called multiple times for Codec, CNG, RED.
+int AudioCodingModuleImpl::RegisterSendCodec(const CodecInst& send_codec) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (!encoder_factory_->codec_manager.RegisterEncoder(send_codec)) {
+    return -1;
+  }
+  if (encoder_factory_->codec_manager.GetCodecInst()) {
+    encoder_factory_->external_speech_encoder = nullptr;
+  }
+  if (!CreateSpeechEncoderIfNecessary(encoder_factory_.get())) {
+    return -1;
+  }
+  auto* sp = encoder_factory_->codec_manager.GetStackParams();
+  if (sp->speech_encoder)
+    encoder_stack_ = encoder_factory_->rent_a_codec.RentEncoderStack(sp);
+  return 0;
+}
+
+void AudioCodingModuleImpl::RegisterExternalSendCodec(
+    AudioEncoder* external_speech_encoder) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  encoder_factory_->codec_manager.UnsetCodecInst();
+  encoder_factory_->external_speech_encoder = external_speech_encoder;
+  RTC_CHECK(CreateSpeechEncoderIfNecessary(encoder_factory_.get()));
+  auto* sp = encoder_factory_->codec_manager.GetStackParams();
+  RTC_CHECK(sp->speech_encoder);
+  encoder_stack_ = encoder_factory_->rent_a_codec.RentEncoderStack(sp);
+}
+
+void AudioCodingModuleImpl::ModifyEncoder(
+    FunctionView<void(std::unique_ptr<AudioEncoder>*)> modifier) {
+  rtc::CritScope lock(&acm_crit_sect_);
+
+  // Wipe the encoder factory, so that everything that relies on it will fail.
+  // We don't want the complexity of supporting swapping back and forth.
+  if (encoder_factory_) {
+    encoder_factory_.reset();
+    RTC_CHECK(!encoder_stack_);  // Ensure we hadn't started using the factory.
+  }
+
+  modifier(&encoder_stack_);
+}
+
+// Get current send codec.
+rtc::Optional<CodecInst> AudioCodingModuleImpl::SendCodec() const {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (encoder_factory_) {
+    auto* ci = encoder_factory_->codec_manager.GetCodecInst();
+    if (ci) {
+      return rtc::Optional<CodecInst>(*ci);
+    }
+    CreateSpeechEncoderIfNecessary(encoder_factory_.get());
+    const std::unique_ptr<AudioEncoder>& enc =
+        encoder_factory_->codec_manager.GetStackParams()->speech_encoder;
+    if (enc) {
+      return rtc::Optional<CodecInst>(
+          acm2::CodecManager::ForgeCodecInst(enc.get()));
+    }
+    return rtc::Optional<CodecInst>();
+  } else {
+    return encoder_stack_
+               ? rtc::Optional<CodecInst>(
+                     acm2::CodecManager::ForgeCodecInst(encoder_stack_.get()))
+               : rtc::Optional<CodecInst>();
+  }
+}
+
+// Get current send frequency.
+int AudioCodingModuleImpl::SendFrequency() const {
+  WEBRTC_TRACE(webrtc::kTraceStream, webrtc::kTraceAudioCoding, id_,
+               "SendFrequency()");
+  rtc::CritScope lock(&acm_crit_sect_);
+
+  if (!encoder_stack_) {
+    WEBRTC_TRACE(webrtc::kTraceStream, webrtc::kTraceAudioCoding, id_,
+                 "SendFrequency Failed, no codec is registered");
+    return -1;
+  }
+
+  return encoder_stack_->SampleRateHz();
+}
+
+void AudioCodingModuleImpl::SetBitRate(int bitrate_bps) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (encoder_stack_) {
+    encoder_stack_->SetTargetBitrate(bitrate_bps);
+  }
+}
+
+// Register a transport callback which will be called to deliver
+// the encoded buffers.
+int AudioCodingModuleImpl::RegisterTransportCallback(
+    AudioPacketizationCallback* transport) {
+  rtc::CritScope lock(&callback_crit_sect_);
+  packetization_callback_ = transport;
+  return 0;
+}
+
+// Add 10MS of raw (PCM) audio data to the encoder.
+int AudioCodingModuleImpl::Add10MsData(const AudioFrame& audio_frame) {
+  InputData input_data;
+  rtc::CritScope lock(&acm_crit_sect_);
+  int r = Add10MsDataInternal(audio_frame, &input_data);
+  return r < 0 ? r : Encode(input_data);
+}
+
+int AudioCodingModuleImpl::Add10MsDataInternal(const AudioFrame& audio_frame,
+                                               InputData* input_data) {
+  if (audio_frame.samples_per_channel_ == 0) {
+    assert(false);
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Cannot Add 10 ms audio, payload length is zero");
+    return -1;
+  }
+
+  if (audio_frame.sample_rate_hz_ > 48000) {
+    assert(false);
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Cannot Add 10 ms audio, input frequency not valid");
+    return -1;
+  }
+
+  // If the length and frequency matches. We currently just support raw PCM.
+  if (static_cast<size_t>(audio_frame.sample_rate_hz_ / 100) !=
+      audio_frame.samples_per_channel_) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Cannot Add 10 ms audio, input frequency and length doesn't"
+                 " match");
+    return -1;
+  }
+
+  if (audio_frame.num_channels_ != 1 && audio_frame.num_channels_ != 2) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Cannot Add 10 ms audio, invalid number of channels.");
+    return -1;
+  }
+
+  // Do we have a codec registered?
+  if (!HaveValidEncoder("Add10MsData")) {
+    return -1;
+  }
+
+  const AudioFrame* ptr_frame;
+  // Perform a resampling, also down-mix if it is required and can be
+  // performed before resampling (a down mix prior to resampling will take
+  // place if both primary and secondary encoders are mono and input is in
+  // stereo).
+  if (PreprocessToAddData(audio_frame, &ptr_frame) < 0) {
+    return -1;
+  }
+
+  // Check whether we need an up-mix or down-mix?
+  const size_t current_num_channels = encoder_stack_->NumChannels();
+  const bool same_num_channels =
+      ptr_frame->num_channels_ == current_num_channels;
+
+  if (!same_num_channels) {
+    if (ptr_frame->num_channels_ == 1) {
+      if (UpMix(*ptr_frame, WEBRTC_10MS_PCM_AUDIO, input_data->buffer) < 0)
+        return -1;
+    } else {
+      if (DownMix(*ptr_frame, WEBRTC_10MS_PCM_AUDIO, input_data->buffer) < 0)
+        return -1;
+    }
+  }
+
+  // When adding data to encoders this pointer is pointing to an audio buffer
+  // with correct number of channels.
+  const int16_t* ptr_audio = ptr_frame->data_;
+
+  // For pushing data to primary, point the |ptr_audio| to correct buffer.
+  if (!same_num_channels)
+    ptr_audio = input_data->buffer;
+
+  input_data->input_timestamp = ptr_frame->timestamp_;
+  input_data->audio = ptr_audio;
+  input_data->length_per_channel = ptr_frame->samples_per_channel_;
+  input_data->audio_channel = current_num_channels;
+
+  return 0;
+}
+
+// Perform a resampling and down-mix if required. We down-mix only if
+// encoder is mono and input is stereo. In case of dual-streaming, both
+// encoders has to be mono for down-mix to take place.
+// |*ptr_out| will point to the pre-processed audio-frame. If no pre-processing
+// is required, |*ptr_out| points to |in_frame|.
+int AudioCodingModuleImpl::PreprocessToAddData(const AudioFrame& in_frame,
+                                               const AudioFrame** ptr_out) {
+  const bool resample =
+      in_frame.sample_rate_hz_ != encoder_stack_->SampleRateHz();
+
+  // This variable is true if primary codec and secondary codec (if exists)
+  // are both mono and input is stereo.
+  // TODO(henrik.lundin): This condition should probably be
+  //   in_frame.num_channels_ > encoder_stack_->NumChannels()
+  const bool down_mix =
+      in_frame.num_channels_ == 2 && encoder_stack_->NumChannels() == 1;
+
+  if (!first_10ms_data_) {
+    expected_in_ts_ = in_frame.timestamp_;
+    expected_codec_ts_ = in_frame.timestamp_;
+    first_10ms_data_ = true;
+  } else if (in_frame.timestamp_ != expected_in_ts_) {
+    // TODO(turajs): Do we need a warning here.
+    expected_codec_ts_ +=
+        (in_frame.timestamp_ - expected_in_ts_) *
+        static_cast<uint32_t>(
+            static_cast<double>(encoder_stack_->SampleRateHz()) /
+            static_cast<double>(in_frame.sample_rate_hz_));
+    expected_in_ts_ = in_frame.timestamp_;
+  }
+
+
+  if (!down_mix && !resample) {
+    // No pre-processing is required.
+    expected_in_ts_ += static_cast<uint32_t>(in_frame.samples_per_channel_);
+    expected_codec_ts_ += static_cast<uint32_t>(in_frame.samples_per_channel_);
+    *ptr_out = &in_frame;
+    return 0;
+  }
+
+  *ptr_out = &preprocess_frame_;
+  preprocess_frame_.num_channels_ = in_frame.num_channels_;
+  int16_t audio[WEBRTC_10MS_PCM_AUDIO];
+  const int16_t* src_ptr_audio = in_frame.data_;
+  int16_t* dest_ptr_audio = preprocess_frame_.data_;
+  if (down_mix) {
+    // If a resampling is required the output of a down-mix is written into a
+    // local buffer, otherwise, it will be written to the output frame.
+    if (resample)
+      dest_ptr_audio = audio;
+    if (DownMix(in_frame, WEBRTC_10MS_PCM_AUDIO, dest_ptr_audio) < 0)
+      return -1;
+    preprocess_frame_.num_channels_ = 1;
+    // Set the input of the resampler is the down-mixed signal.
+    src_ptr_audio = audio;
+  }
+
+  preprocess_frame_.timestamp_ = expected_codec_ts_;
+  preprocess_frame_.samples_per_channel_ = in_frame.samples_per_channel_;
+  preprocess_frame_.sample_rate_hz_ = in_frame.sample_rate_hz_;
+  // If it is required, we have to do a resampling.
+  if (resample) {
+    // The result of the resampler is written to output frame.
+    dest_ptr_audio = preprocess_frame_.data_;
+
+    int samples_per_channel = resampler_.Resample10Msec(
+        src_ptr_audio, in_frame.sample_rate_hz_, encoder_stack_->SampleRateHz(),
+        preprocess_frame_.num_channels_, AudioFrame::kMaxDataSizeSamples,
+        dest_ptr_audio);
+
+    if (samples_per_channel < 0) {
+      WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                   "Cannot add 10 ms audio, resampling failed");
+      return -1;
+    }
+    preprocess_frame_.samples_per_channel_ =
+        static_cast<size_t>(samples_per_channel);
+    preprocess_frame_.sample_rate_hz_ = encoder_stack_->SampleRateHz();
+  }
+
+  expected_codec_ts_ +=
+      static_cast<uint32_t>(preprocess_frame_.samples_per_channel_);
+  expected_in_ts_ += static_cast<uint32_t>(in_frame.samples_per_channel_);
+
+  return 0;
+}
+
+/////////////////////////////////////////
+//   (RED) Redundant Coding
+//
+
+bool AudioCodingModuleImpl::REDStatus() const {
+  rtc::CritScope lock(&acm_crit_sect_);
+  return encoder_factory_->codec_manager.GetStackParams()->use_red;
+}
+
+// Configure RED status i.e on/off.
+int AudioCodingModuleImpl::SetREDStatus(bool enable_red) {
+#ifdef WEBRTC_CODEC_RED
+  rtc::CritScope lock(&acm_crit_sect_);
+  CreateSpeechEncoderIfNecessary(encoder_factory_.get());
+  if (!encoder_factory_->codec_manager.SetCopyRed(enable_red)) {
+    return -1;
+  }
+  auto* sp = encoder_factory_->codec_manager.GetStackParams();
+  if (sp->speech_encoder)
+    encoder_stack_ = encoder_factory_->rent_a_codec.RentEncoderStack(sp);
+  return 0;
+#else
+  WEBRTC_TRACE(webrtc::kTraceWarning, webrtc::kTraceAudioCoding, id_,
+               "  WEBRTC_CODEC_RED is undefined");
+  return -1;
+#endif
+}
+
+/////////////////////////////////////////
+//   (FEC) Forward Error Correction (codec internal)
+//
+
+bool AudioCodingModuleImpl::CodecFEC() const {
+  rtc::CritScope lock(&acm_crit_sect_);
+  return encoder_factory_->codec_manager.GetStackParams()->use_codec_fec;
+}
+
+int AudioCodingModuleImpl::SetCodecFEC(bool enable_codec_fec) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  CreateSpeechEncoderIfNecessary(encoder_factory_.get());
+  if (!encoder_factory_->codec_manager.SetCodecFEC(enable_codec_fec)) {
+    return -1;
+  }
+  auto* sp = encoder_factory_->codec_manager.GetStackParams();
+  if (sp->speech_encoder)
+    encoder_stack_ = encoder_factory_->rent_a_codec.RentEncoderStack(sp);
+  if (enable_codec_fec) {
+    return sp->use_codec_fec ? 0 : -1;
+  } else {
+    RTC_DCHECK(!sp->use_codec_fec);
+    return 0;
+  }
+}
+
+int AudioCodingModuleImpl::SetPacketLossRate(int loss_rate) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (HaveValidEncoder("SetPacketLossRate")) {
+    encoder_stack_->SetProjectedPacketLossRate(loss_rate / 100.0);
+  }
+  return 0;
+}
+
+/////////////////////////////////////////
+//   (VAD) Voice Activity Detection
+//
+int AudioCodingModuleImpl::SetVAD(bool enable_dtx,
+                                  bool enable_vad,
+                                  ACMVADMode mode) {
+  // Note: |enable_vad| is not used; VAD is enabled based on the DTX setting.
+  RTC_DCHECK_EQ(enable_dtx, enable_vad);
+  rtc::CritScope lock(&acm_crit_sect_);
+  CreateSpeechEncoderIfNecessary(encoder_factory_.get());
+  if (!encoder_factory_->codec_manager.SetVAD(enable_dtx, mode)) {
+    return -1;
+  }
+  auto* sp = encoder_factory_->codec_manager.GetStackParams();
+  if (sp->speech_encoder)
+    encoder_stack_ = encoder_factory_->rent_a_codec.RentEncoderStack(sp);
+  return 0;
+}
+
+// Get VAD/DTX settings.
+int AudioCodingModuleImpl::VAD(bool* dtx_enabled, bool* vad_enabled,
+                               ACMVADMode* mode) const {
+  rtc::CritScope lock(&acm_crit_sect_);
+  const auto* sp = encoder_factory_->codec_manager.GetStackParams();
+  *dtx_enabled = *vad_enabled = sp->use_cng;
+  *mode = sp->vad_mode;
+  return 0;
+}
+
+/////////////////////////////////////////
+//   Receiver
+//
+
+int AudioCodingModuleImpl::InitializeReceiver() {
+  rtc::CritScope lock(&acm_crit_sect_);
+  return InitializeReceiverSafe();
+}
+
+// Initialize receiver, resets codec database etc.
+int AudioCodingModuleImpl::InitializeReceiverSafe() {
+  // If the receiver is already initialized then we want to destroy any
+  // existing decoders. After a call to this function, we should have a clean
+  // start-up.
+  if (receiver_initialized_) {
+    if (receiver_.RemoveAllCodecs() < 0)
+      return -1;
+  }
+  receiver_.ResetInitialDelay();
+  receiver_.SetMinimumDelay(0);
+  receiver_.SetMaximumDelay(0);
+  receiver_.FlushBuffers();
+
+  // Register RED and CN.
+  auto db = acm2::RentACodec::Database();
+  for (size_t i = 0; i < db.size(); i++) {
+    if (IsCodecRED(db[i]) || IsCodecCN(db[i])) {
+      if (receiver_.AddCodec(static_cast<int>(i),
+                             static_cast<uint8_t>(db[i].pltype), 1,
+                             db[i].plfreq, nullptr, db[i].plname) < 0) {
+        WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                     "Cannot register master codec.");
+        return -1;
+      }
+    }
+  }
+  receiver_initialized_ = true;
+  return 0;
+}
+
+// Get current receive frequency.
+int AudioCodingModuleImpl::ReceiveFrequency() const {
+  const auto last_packet_sample_rate = receiver_.last_packet_sample_rate_hz();
+  return last_packet_sample_rate ? *last_packet_sample_rate
+                                 : receiver_.last_output_sample_rate_hz();
+}
+
+// Get current playout frequency.
+int AudioCodingModuleImpl::PlayoutFrequency() const {
+  WEBRTC_TRACE(webrtc::kTraceStream, webrtc::kTraceAudioCoding, id_,
+               "PlayoutFrequency()");
+  return receiver_.last_output_sample_rate_hz();
+}
+
+int AudioCodingModuleImpl::RegisterReceiveCodec(const CodecInst& codec) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  auto* ef = encoder_factory_.get();
+  return RegisterReceiveCodecUnlocked(
+      codec, [&] { return ef->rent_a_codec.RentIsacDecoder(codec.plfreq); });
+}
+
+int AudioCodingModuleImpl::RegisterReceiveCodec(
+    const CodecInst& codec,
+    FunctionView<std::unique_ptr<AudioDecoder>()> isac_factory) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  return RegisterReceiveCodecUnlocked(codec, isac_factory);
+}
+
+int AudioCodingModuleImpl::RegisterReceiveCodecUnlocked(
+    const CodecInst& codec,
+    FunctionView<std::unique_ptr<AudioDecoder>()> isac_factory) {
+  RTC_DCHECK(receiver_initialized_);
+  if (codec.channels > 2) {
+    LOG_F(LS_ERROR) << "Unsupported number of channels: " << codec.channels;
+    return -1;
+  }
+
+  auto codec_id = acm2::RentACodec::CodecIdByParams(codec.plname, codec.plfreq,
+                                                    codec.channels);
+  if (!codec_id) {
+    LOG_F(LS_ERROR) << "Wrong codec params to be registered as receive codec";
+    return -1;
+  }
+  auto codec_index = acm2::RentACodec::CodecIndexFromId(*codec_id);
+  RTC_CHECK(codec_index) << "Invalid codec ID: " << static_cast<int>(*codec_id);
+
+  // Check if the payload-type is valid.
+  if (!acm2::RentACodec::IsPayloadTypeValid(codec.pltype)) {
+    LOG_F(LS_ERROR) << "Invalid payload type " << codec.pltype << " for "
+                    << codec.plname;
+    return -1;
+  }
+
+  AudioDecoder* isac_decoder = nullptr;
+  if (STR_CASE_CMP(codec.plname, "isac") == 0) {
+    std::unique_ptr<AudioDecoder>& saved_isac_decoder =
+        codec.plfreq == 16000 ? isac_decoder_16k_ : isac_decoder_32k_;
+    if (!saved_isac_decoder) {
+      saved_isac_decoder = isac_factory();
+    }
+    isac_decoder = saved_isac_decoder.get();
+  }
+  return receiver_.AddCodec(*codec_index, codec.pltype, codec.channels,
+                            codec.plfreq, isac_decoder, codec.plname);
+}
+
+int AudioCodingModuleImpl::RegisterExternalReceiveCodec(
+    int rtp_payload_type,
+    AudioDecoder* external_decoder,
+    int sample_rate_hz,
+    int num_channels,
+    const std::string& name) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  RTC_DCHECK(receiver_initialized_);
+  if (num_channels > 2 || num_channels < 0) {
+    LOG_F(LS_ERROR) << "Unsupported number of channels: " << num_channels;
+    return -1;
+  }
+
+  // Check if the payload-type is valid.
+  if (!acm2::RentACodec::IsPayloadTypeValid(rtp_payload_type)) {
+    LOG_F(LS_ERROR) << "Invalid payload-type " << rtp_payload_type
+                    << " for external decoder.";
+    return -1;
+  }
+
+  return receiver_.AddCodec(-1 /* external */, rtp_payload_type, num_channels,
+                            sample_rate_hz, external_decoder, name);
+}
+
+// Get current received codec.
+int AudioCodingModuleImpl::ReceiveCodec(CodecInst* current_codec) const {
+  rtc::CritScope lock(&acm_crit_sect_);
+  return receiver_.LastAudioCodec(current_codec);
+}
+
+// Incoming packet from network parsed and ready for decode.
+int AudioCodingModuleImpl::IncomingPacket(const uint8_t* incoming_payload,
+                                          const size_t payload_length,
+                                          const WebRtcRTPHeader& rtp_header) {
+  return receiver_.InsertPacket(
+      rtp_header,
+      rtc::ArrayView<const uint8_t>(incoming_payload, payload_length));
+}
+
+// Minimum playout delay (Used for lip-sync).
+int AudioCodingModuleImpl::SetMinimumPlayoutDelay(int time_ms) {
+  if ((time_ms < 0) || (time_ms > 10000)) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Delay must be in the range of 0-1000 milliseconds.");
+    return -1;
+  }
+  return receiver_.SetMinimumDelay(time_ms);
+}
+
+int AudioCodingModuleImpl::SetMaximumPlayoutDelay(int time_ms) {
+  if ((time_ms < 0) || (time_ms > 10000)) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "Delay must be in the range of 0-1000 milliseconds.");
+    return -1;
+  }
+  return receiver_.SetMaximumDelay(time_ms);
+}
+
+// Get 10 milliseconds of raw audio data to play out.
+// Automatic resample to the requested frequency.
+int AudioCodingModuleImpl::PlayoutData10Ms(int desired_freq_hz,
+                                           AudioFrame* audio_frame,
+                                           bool* muted) {
+  // GetAudio always returns 10 ms, at the requested sample rate.
+  if (receiver_.GetAudio(desired_freq_hz, audio_frame, muted) != 0) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "PlayoutData failed, RecOut Failed");
+    return -1;
+  }
+  audio_frame->id_ = id_;
+  return 0;
+}
+
+int AudioCodingModuleImpl::PlayoutData10Ms(int desired_freq_hz,
+                                           AudioFrame* audio_frame) {
+  bool muted;
+  int ret = PlayoutData10Ms(desired_freq_hz, audio_frame, &muted);
+  RTC_DCHECK(!muted);
+  return ret;
+}
+
+/////////////////////////////////////////
+//   Statistics
+//
+
+// TODO(turajs) change the return value to void. Also change the corresponding
+// NetEq function.
+int AudioCodingModuleImpl::GetNetworkStatistics(NetworkStatistics* statistics) {
+  receiver_.GetNetworkStatistics(statistics);
+  return 0;
+}
+
+int AudioCodingModuleImpl::RegisterVADCallback(ACMVADCallback* vad_callback) {
+  WEBRTC_TRACE(webrtc::kTraceDebug, webrtc::kTraceAudioCoding, id_,
+               "RegisterVADCallback()");
+  rtc::CritScope lock(&callback_crit_sect_);
+  vad_callback_ = vad_callback;
+  return 0;
+}
+
+// TODO(kwiberg): Remove this method, and have callers call IncomingPacket
+// instead. The translation logic and state belong with them, not with
+// AudioCodingModuleImpl.
+int AudioCodingModuleImpl::IncomingPayload(const uint8_t* incoming_payload,
+                                           size_t payload_length,
+                                           uint8_t payload_type,
+                                           uint32_t timestamp) {
+  // We are not acquiring any lock when interacting with |aux_rtp_header_| no
+  // other method uses this member variable.
+  if (!aux_rtp_header_) {
+    // This is the first time that we are using |dummy_rtp_header_|
+    // so we have to create it.
+    aux_rtp_header_.reset(new WebRtcRTPHeader);
+    aux_rtp_header_->header.payloadType = payload_type;
+    // Don't matter in this case.
+    aux_rtp_header_->header.ssrc = 0;
+    aux_rtp_header_->header.markerBit = false;
+    // Start with random numbers.
+    aux_rtp_header_->header.sequenceNumber = 0x1234;  // Arbitrary.
+    aux_rtp_header_->type.Audio.channel = 1;
+  }
+
+  aux_rtp_header_->header.timestamp = timestamp;
+  IncomingPacket(incoming_payload, payload_length, *aux_rtp_header_);
+  // Get ready for the next payload.
+  aux_rtp_header_->header.sequenceNumber++;
+  return 0;
+}
+
+int AudioCodingModuleImpl::SetOpusApplication(OpusApplicationMode application) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (!HaveValidEncoder("SetOpusApplication")) {
+    return -1;
+  }
+  AudioEncoder::Application app;
+  switch (application) {
+    case kVoip:
+      app = AudioEncoder::Application::kSpeech;
+      break;
+    case kAudio:
+      app = AudioEncoder::Application::kAudio;
+      break;
+    default:
+      FATAL();
+      return 0;
+  }
+  return encoder_stack_->SetApplication(app) ? 0 : -1;
+}
+
+// Informs Opus encoder of the maximum playback rate the receiver will render.
+int AudioCodingModuleImpl::SetOpusMaxPlaybackRate(int frequency_hz) {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (!HaveValidEncoder("SetOpusMaxPlaybackRate")) {
+    return -1;
+  }
+  encoder_stack_->SetMaxPlaybackRate(frequency_hz);
+  return 0;
+}
+
+int AudioCodingModuleImpl::EnableOpusDtx() {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (!HaveValidEncoder("EnableOpusDtx")) {
+    return -1;
+  }
+  return encoder_stack_->SetDtx(true) ? 0 : -1;
+}
+
+int AudioCodingModuleImpl::DisableOpusDtx() {
+  rtc::CritScope lock(&acm_crit_sect_);
+  if (!HaveValidEncoder("DisableOpusDtx")) {
+    return -1;
+  }
+  return encoder_stack_->SetDtx(false) ? 0 : -1;
+}
+
+int32_t AudioCodingModuleImpl::PlayoutTimestamp(uint32_t* timestamp) {
+  rtc::Optional<uint32_t> ts = PlayoutTimestamp();
+  if (!ts)
+    return -1;
+  *timestamp = *ts;
+  return 0;
+}
+
+rtc::Optional<uint32_t> AudioCodingModuleImpl::PlayoutTimestamp() {
+  return receiver_.GetPlayoutTimestamp();
+}
+
+bool AudioCodingModuleImpl::HaveValidEncoder(const char* caller_name) const {
+  if (!encoder_stack_) {
+    WEBRTC_TRACE(webrtc::kTraceError, webrtc::kTraceAudioCoding, id_,
+                 "%s failed: No send codec is registered.", caller_name);
+    return false;
+  }
+  return true;
+}
+
+int AudioCodingModuleImpl::UnregisterReceiveCodec(uint8_t payload_type) {
+  return receiver_.RemoveCodec(payload_type);
+}
+
+int AudioCodingModuleImpl::EnableNack(size_t max_nack_list_size) {
+  return receiver_.EnableNack(max_nack_list_size);
+}
+
+void AudioCodingModuleImpl::DisableNack() {
+  receiver_.DisableNack();
+}
+
+std::vector<uint16_t> AudioCodingModuleImpl::GetNackList(
+    int64_t round_trip_time_ms) const {
+  return receiver_.GetNackList(round_trip_time_ms);
+}
+
+int AudioCodingModuleImpl::LeastRequiredDelayMs() const {
+  return receiver_.LeastRequiredDelayMs();
+}
+
+void AudioCodingModuleImpl::GetDecodingCallStatistics(
+      AudioDecodingCallStats* call_stats) const {
+  receiver_.GetDecodingCallStatistics(call_stats);
+}
+
+}  // namespace
+
 // Create module
 AudioCodingModule* AudioCodingModule::Create(int id) {
   Config config;
@@ -43,9 +1261,9 @@ AudioCodingModule* AudioCodingModule::Create(const Config& config) {
     // cycle.
     Config config_copy = config;
     config_copy.decoder_factory = CreateBuiltinAudioDecoderFactory();
-    return new acm2::AudioCodingModuleImpl(config_copy);
+    return new AudioCodingModuleImpl(config_copy);
   }
-  return new acm2::AudioCodingModuleImpl(config);
+  return new AudioCodingModuleImpl(config);
 }
 
 int AudioCodingModule::NumberOfCodecs() {