NetEq: Implement muted output

webrtc/modules/audio_coding/neteq/neteq_impl.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 90 matching lines @@
       reset_decoder_(false),
       current_rtp_payload_type_(0xFF),      // Invalid RTP payload type.
       current_cng_rtp_payload_type_(0xFF),  // Invalid RTP payload type.
       ssrc_(0),
       first_packet_(true),
       error_code_(0),
       decoder_error_code_(0),
       background_noise_mode_(config.background_noise_mode),
       playout_mode_(config.playout_mode),
       enable_fast_accelerate_(config.enable_fast_accelerate),
-      nack_enabled_(false) {
+      nack_enabled_(false),
+      enable_muted_state_(config.enable_muted_state) {
   LOG(LS_INFO) << "NetEq config: " << config.ToString();
   int fs = config.sample_rate_hz;
   if (fs != 8000 && fs != 16000 && fs != 32000 && fs != 48000) {
     LOG(LS_ERROR) << "Sample rate " << fs << " Hz not supported. " <<
         "Changing to 8000 Hz.";
     fs = 8000;
   }
   delay_manager_->SetMaximumDelay(config.max_delay_ms);
   fs_hz_ = fs;
   fs_mult_ = fs / 8000;
@@ skipping 75 matching lines @@
     }
     default:
       RTC_NOTREACHED();
   }
   if (!vad_enabled) {
     // Always set kVadUnknown when receive VAD is inactive.
     audio_frame->vad_activity_ = AudioFrame::kVadUnknown;
   }
 }
 }  // namespace
 

[minyue-webrtc, 2016/05/11 11:29:54]

how about allowing the bool* to be nullptr. calling does not need to define for
it if it is not cared.

[hlundin-webrtc, 2016/05/12 07:44:40]

That is going to be a bit tricky, I think. What if you have enabled muted state
(through config.enable_muted_state), but you don't provide a valid pointer?
Should NetEq still be allowed to enter muted state, and leave the output samples
possibly undefined?

[minyue-webrtc, 2016/05/12 10:56:06]

good point.

-int NetEqImpl::GetAudio(AudioFrame* audio_frame) {
+int NetEqImpl::GetAudio(AudioFrame* audio_frame, bool* muted_output) {
   TRACE_EVENT0("webrtc", "NetEqImpl::GetAudio");
   rtc::CritScope lock(&crit_sect_);
-  int error = GetAudioInternal(audio_frame);
+  int error = GetAudioInternal(audio_frame, muted_output);
   RTC_DCHECK_EQ(
       audio_frame->sample_rate_hz_,
       rtc::checked_cast<int>(audio_frame->samples_per_channel_ * 100));
   if (error != 0) {
     error_code_ = error;
     return kFail;
   }
   SetAudioFrameActivityAndType(vad_->enabled(), LastOutputType(),
                                last_vad_activity_, audio_frame);
   last_vad_activity_ = audio_frame->vad_activity_;
@@ skipping 580 matching lines @@
   } else if (delay_manager_->last_pack_cng_or_dtmf() == -1) {
     // This is first "normal" packet after CNG or DTMF.
     // Reset packet time counter and measure time until next packet,
     // but don't update statistics.
     delay_manager_->set_last_pack_cng_or_dtmf(0);
     delay_manager_->ResetPacketIatCount();
   }
   return 0;
 }
 
-int NetEqImpl::GetAudioInternal(AudioFrame* audio_frame) {
+int NetEqImpl::GetAudioInternal(AudioFrame* audio_frame, bool* muted_output) {
   PacketList packet_list;
   DtmfEvent dtmf_event;
   Operations operation;
   bool play_dtmf;
+  *muted_output = false;
   tick_timer_->Increment();
   stats_.IncreaseCounter(output_size_samples_, fs_hz_);
+
+  // Check for muted state.
+  if (enable_muted_state_ && expand_->Muted() && packet_buffer_->Empty()) {

[minyue-webrtc, 2016/05/11 11:29:53]

what if packet_buffer_ are not empty but all old packets?

[hlundin-webrtc, 2016/05/12 07:44:40]

I think we want to exit muted state for this. It is safer, I think. It should be
rare, so exiting muted state for this reason is an acceptable cost IMO.

+    RTC_DCHECK_EQ(last_mode_, kModeExpand);

[minyue-webrtc, 2016/05/11 11:29:53]

why should this be a CHECK but not a if condition?

[hlundin-webrtc, 2016/05/12 07:44:40]

The logic in NetEq should lead to this being always true. Otherwise, we are
doing something wrong in the programming. Hence, DCHECK.

+    playout_timestamp_ += static_cast<uint32_t>(output_size_samples_);
+    audio_frame->sample_rate_hz_ = fs_hz_;
+    audio_frame->samples_per_channel_ = output_size_samples_;
+    audio_frame->timestamp_ =

[hlundin-webrtc, 2016/05/10 12:28:15]

The setting of timestamp is identical to line 1028 at the end of
GetAudioInternal.

+        first_packet_
+            ? 0
+            : timestamp_scaler_->ToExternal(playout_timestamp_) -
+                  static_cast<uint32_t>(audio_frame->samples_per_channel_);
+    audio_frame->num_channels_ = sync_buffer_->Channels();
+    *muted_output = true;
+    return 0;
+  }
+
   int return_value = GetDecision(&operation, &packet_list, &dtmf_event,
                                  &play_dtmf);
   if (return_value != 0) {
     last_mode_ = kModeError;
     return return_value;
   }
 
   AudioDecoder::SpeechType speech_type;
   int length = 0;
   int decode_return_value = Decode(&packet_list, &operation,
@@ skipping 1315 matching lines @@
   }
 }
 
 void NetEqImpl::CreateDecisionLogic() {
   decision_logic_.reset(DecisionLogic::Create(
       fs_hz_, output_size_samples_, playout_mode_, decoder_database_.get(),
       *packet_buffer_.get(), delay_manager_.get(), buffer_level_filter_.get(),
       tick_timer_.get()));
 }
 }  // namespace webrtc