diff --git a/webrtc/modules/audio_coding/main/acm2/acm_codec_database.cc b/webrtc/modules/audio_coding/main/acm2/acm_codec_database.cc
index f99c85b494..225098aade 100644
--- a/webrtc/modules/audio_coding/main/acm2/acm_codec_database.cc
+++ b/webrtc/modules/audio_coding/main/acm2/acm_codec_database.cc
@@ -270,7 +270,7 @@ const ACMCodecDB::CodecSettings ACMCodecDB::codec_settings_[] = {
     // Opus supports frames shorter than 10ms,
     // but it doesn't help us to use them.
     // Mono and stereo.
-    {1, {960}, 0, 2, false},
+    {4, {480, 960, 1920, 2880}, 0, 2, false},
 #endif
 #ifdef WEBRTC_CODEC_SPEEX
     {3, {160, 320, 480}, 0, 1, false},
diff --git a/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc b/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc
index 949a70558d..d5acfac367 100644
--- a/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc
+++ b/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc
@@ -545,6 +545,8 @@ int AcmReceiver::RemoveAllCodecs() {
       }
     }
   }
+  // No codec is registered, invalidate last audio decoder.
+  last_audio_decoder_ = -1;
   return ret_val;
 }
 
@@ -561,6 +563,8 @@ int AcmReceiver::RemoveCodec(uint8_t payload_type) {
   }
   CriticalSectionScoped lock(neteq_crit_sect_);
   decoders_[codec_index].registered = false;
+  if (last_audio_decoder_ == codec_index)
+    last_audio_decoder_ = -1;  // Codec is removed, invalidate last decoder.
   return 0;
 }
 
diff --git a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
index 3a7d271810..3c704c2274 100644
--- a/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
+++ b/webrtc/modules/audio_coding/main/acm2/audio_coding_module_impl.cc
@@ -1536,8 +1536,7 @@ int AudioCodingModuleImpl::InitializeReceiverSafe() {
 // removing and registering a decoder we can achieve the effect of resetting.
 // Reset the decoder state.
 int AudioCodingModuleImpl::ResetDecoder() {
-  CriticalSectionScoped lock(acm_crit_sect_);
-  return -1;
+  return 0;
 }
 
 // Get current receive frequency.