Make an enum class out of NetEqDecoder, and hide the neteq_decoders_ table

webrtc/modules/audio_coding/main/acm2/acm_receiver.cc

 /*
  *  Copyright (c) 2013 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 421 matching lines @@
   }
 
   return 0;
 }
 
 int32_t AcmReceiver::AddCodec(int acm_codec_id,
                               uint8_t payload_type,
                               int channels,
                               int sample_rate_hz,
                               AudioDecoder* audio_decoder) {
-  assert(acm_codec_id >= -1);  // -1 means external decoder
-  NetEqDecoder neteq_decoder = (acm_codec_id == -1)
-                                   ? kDecoderArbitrary
-                                   : ACMCodecDB::neteq_decoders_[acm_codec_id];
-
-  // Make sure the right decoder is registered for Opus.
-  if (neteq_decoder == kDecoderOpus && channels == 2) {
-    neteq_decoder = kDecoderOpus_2ch;
-  }
+  const auto neteq_decoder = [acm_codec_id, channels]() -> NetEqDecoder {
+    if (acm_codec_id == -1)
+      return NetEqDecoder::kDecoderArbitrary;  // External decoder.
+    const rtc::Maybe<RentACodec::CodecId> cid =
+        RentACodec::CodecIdFromIndex(acm_codec_id);
+    RTC_DCHECK(cid);  // acm_codec_id was a valid codec index.

[hlundin-webrtc, 2015/10/28 15:14:47]

I prefer you stream the debug information to RTC_DCHECK for improved
debuggability.

[kwiberg-webrtc, 2015/10/29 09:29:15]

Done.

+    const rtc::Maybe<NetEqDecoder> ned =
+        RentACodec::NetEqDecoderFromCodecId(*cid, channels);
+    RTC_DCHECK(ned);  // CodecIdFromIndex gives a valid CodecId.
+    return *ned;
+  }();
 
   CriticalSectionScoped lock(crit_sect_.get());
 
   // The corresponding NetEq decoder ID.
   // If this codec has been registered before.
   auto it = decoders_.find(payload_type);
   if (it != decoders_.end()) {
     const Decoder& decoder = it->second;
     if (acm_codec_id != -1 && decoder.acm_codec_id == acm_codec_id &&
         decoder.channels == channels &&
@@ skipping 325 matching lines @@
 
 void AcmReceiver::GetDecodingCallStatistics(
     AudioDecodingCallStats* stats) const {
   CriticalSectionScoped lock(crit_sect_.get());
   *stats = call_stats_.GetDecodingStatistics();
 }
 
 }  // namespace acm2
 
 }  // namespace webrtc