Convert CNG into C++ and remove it from AudioDecoder

webrtc/modules/audio_coding/neteq/neteq_impl.cc

Index: webrtc/modules/audio_coding/neteq/neteq_impl.cc
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index db37e716d66dde966a4cac42f10dd47166c4f42c..ae4b70acb2e6390fa4270cc31ffbfde7165123a6 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -14,6 +14,7 @@
 #include <memory.h>  // memset
 
 #include <algorithm>
+#include <vector>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
@@ -664,18 +665,21 @@ int NetEqImpl::InsertPacketInternal(const WebRtcRTPHeader& rtp_header,
     }
   }
 
-  // Update bandwidth estimate, if the packet is not sync-packet.
+  // Update bandwidth estimate, if the packet is not sync-packet nor comfort
+  // noise.

[kwiberg-webrtc, 2016/04/12 13:35:31]

Is this additional requirement because CN's IncomingPacket method didn't do
anything anyway?

[ossu, 2016/04/12 13:54:50]

Well, it just returned -1 before, so the call was just a noop. We still want to
assert (actually, probably RTC_DCHECK) that decoder is valid below, though.

   if (!packet_list.empty() && !packet_list.front()->sync_packet) {
     // The list can be empty here if we got nothing but DTMF payloads.
-    AudioDecoder* decoder =
-        decoder_database_->GetDecoder(main_header.payloadType);
-    assert(decoder);  // Should always get a valid object, since we have
-                      // already checked that the payload types are known.
-    decoder->IncomingPacket(packet_list.front()->payload,
-                            packet_list.front()->payload_length,
-                            packet_list.front()->header.sequenceNumber,
-                            packet_list.front()->header.timestamp,
-                            receive_timestamp);
+    if (!decoder_database_->IsComfortNoise(main_header.payloadType)) {

[kwiberg-webrtc, 2016/04/12 13:35:31]

Merge these two ifs?

[ossu, 2016/04/12 13:54:50]

Acknowledged.

+      AudioDecoder* decoder =
+          decoder_database_->GetDecoder(main_header.payloadType);
+      assert(decoder);  // Should always get a valid object, since we have
+      // already checked that the payload types are known.
+      decoder->IncomingPacket(packet_list.front()->payload,
+                              packet_list.front()->payload_length,
+                              packet_list.front()->header.sequenceNumber,
+                              packet_list.front()->header.timestamp,
+                              receive_timestamp);
+    }
   }
 
   if (nack_enabled_) {
@@ -728,14 +732,18 @@ int NetEqImpl::InsertPacketInternal(const WebRtcRTPHeader& rtp_header,
     const RTPHeader* rtp_header = packet_buffer_->NextRtpHeader();
     assert(rtp_header);
     int payload_type = rtp_header->payloadType;
-    AudioDecoder* decoder = decoder_database_->GetDecoder(payload_type);
-    assert(decoder);  // Payloads are already checked to be valid.
+    size_t channels = 1;
+    if (!decoder_database_->IsComfortNoise(payload_type)) {
+      AudioDecoder* decoder = decoder_database_->GetDecoder(payload_type);
+      assert(decoder);  // Payloads are already checked to be valid.
+      channels = decoder->Channels();
+    }
     const DecoderDatabase::DecoderInfo* decoder_info =
         decoder_database_->GetDecoderInfo(payload_type);
     assert(decoder_info);
     if (decoder_info->fs_hz != fs_hz_ ||
-        decoder->Channels() != algorithm_buffer_->Channels()) {
-      SetSampleRateAndChannels(decoder_info->fs_hz, decoder->Channels());
+        channels != algorithm_buffer_->Channels()) {
+      SetSampleRateAndChannels(decoder_info->fs_hz, channels);
     }
     if (nack_enabled_) {
       RTC_DCHECK(nack_);
@@ -1297,7 +1305,7 @@ int NetEqImpl::Decode(PacketList* packet_list, Operations* operation,
       decoder->Reset();
 
     // Reset comfort noise decoder.
-    AudioDecoder* cng_decoder = decoder_database_->GetActiveCngDecoder();
+    ComfortNoiseDecoder* cng_decoder = decoder_database_->GetActiveCngDecoder();
     if (cng_decoder)
       cng_decoder->Reset();
 
@@ -1955,7 +1963,7 @@ int NetEqImpl::ExtractPackets(size_t required_samples,
           stats_.SecondaryDecodedSamples(packet_duration);
         }
       }
-    } else {
+    } else if (!decoder_database_->IsComfortNoise(packet->header.payloadType)) {
       LOG(LS_WARNING) << "Unknown payload type "
                       << static_cast<int>(packet->header.payloadType);
       assert(false);
@@ -2023,7 +2031,7 @@ void NetEqImpl::SetSampleRateAndChannels(int fs_hz, size_t channels) {
     mute_factor_array_[i] = 16384;  // 1.0 in Q14.
   }
 
-  AudioDecoder* cng_decoder = decoder_database_->GetActiveCngDecoder();
+  ComfortNoiseDecoder* cng_decoder = decoder_database_->GetActiveCngDecoder();
   if (cng_decoder)
     cng_decoder->Reset();