Rename neteq4 folder to neteq

Keep the old neteq4/audio_decoder_unittests.isolate while waiting for
a hard-coded reference to change.

This CL effectively reverts r6257 "Rename neteq4 folder to neteq".

BUG=2996
TBR=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/21629004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6367 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_coding/neteq/timestamp_scaler.cc b/webrtc/modules/audio_coding/neteq/timestamp_scaler.cc
new file mode 100644
index 0000000..0189013
--- /dev/null
+++ b/webrtc/modules/audio_coding/neteq/timestamp_scaler.cc
@@ -0,0 +1,111 @@
+/*
+ *  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.
+ */
+
+#include "webrtc/modules/audio_coding/neteq/timestamp_scaler.h"
+
+#include "webrtc/modules/audio_coding/neteq/decoder_database.h"
+#include "webrtc/modules/audio_coding/neteq/defines.h"
+#include "webrtc/system_wrappers/interface/logging.h"
+
+namespace webrtc {
+
+void TimestampScaler::ToInternal(Packet* packet) {
+  if (!packet) {
+    return;
+  }
+  packet->header.timestamp = ToInternal(packet->header.timestamp,
+                                        packet->header.payloadType);
+}
+
+void TimestampScaler::ToInternal(PacketList* packet_list) {
+  PacketList::iterator it;
+  for (it = packet_list->begin(); it != packet_list->end(); ++it) {
+    ToInternal(*it);
+  }
+}
+
+uint32_t TimestampScaler::ToInternal(uint32_t external_timestamp,
+                                     uint8_t rtp_payload_type) {
+  const DecoderDatabase::DecoderInfo* info =
+      decoder_database_.GetDecoderInfo(rtp_payload_type);
+  if (!info) {
+    // Payload type is unknown. Do not scale.
+    return external_timestamp;
+  }
+  switch (info->codec_type) {
+    case kDecoderG722:
+    case kDecoderG722_2ch: {
+      // Use timestamp scaling with factor 2 (two output samples per RTP
+      // timestamp).
+      numerator_ = 2;
+      denominator_ = 1;
+      break;
+    }
+    case kDecoderOpus:
+    case kDecoderOpus_2ch:
+    case kDecoderISACfb:
+    case kDecoderCNGswb48kHz: {
+      // Use timestamp scaling with factor 2/3 (32 kHz sample rate, but RTP
+      // timestamps run on 48 kHz).
+      // TODO(tlegrand): Remove scaling for kDecoderCNGswb48kHz once ACM has
+      // full 48 kHz support.
+      numerator_ = 2;
+      denominator_ = 3;
+    }
+    case kDecoderAVT:
+    case kDecoderCNGnb:
+    case kDecoderCNGwb:
+    case kDecoderCNGswb32kHz: {
+      // Do not change the timestamp scaling settings for DTMF or CNG.
+      break;
+    }
+    default: {
+      // Do not use timestamp scaling for any other codec.
+      numerator_ = 1;
+      denominator_ = 1;
+      break;
+    }
+  }
+
+  if (!(numerator_ == 1 && denominator_ == 1)) {
+    // We have a scale factor != 1.
+    if (!first_packet_received_) {
+      external_ref_ = external_timestamp;
+      internal_ref_ = external_timestamp;
+      first_packet_received_ = true;
+    }
+    int32_t external_diff = external_timestamp - external_ref_;
+    assert(denominator_ > 0);  // Should not be possible.
+    external_ref_ = external_timestamp;
+    internal_ref_ += (external_diff * numerator_) / denominator_;
+    LOG(LS_VERBOSE) << "Converting timestamp: " << external_timestamp <<
+        " -> " << internal_ref_;
+    return internal_ref_;
+  } else {
+    // No scaling.
+    return external_timestamp;
+  }
+}
+
+
+uint32_t TimestampScaler::ToExternal(uint32_t internal_timestamp) const {
+  if (!first_packet_received_ || (numerator_ == 1 && denominator_ == 1)) {
+    // Not initialized, or scale factor is 1.
+    return internal_timestamp;
+  } else {
+    int32_t internal_diff = internal_timestamp - internal_ref_;
+    assert(numerator_ > 0);  // Should not be possible.
+    // Do not update references in this method.
+    // Switch |denominator_| and |numerator_| to convert the other way.
+    return external_ref_ + (internal_diff * denominator_) / numerator_;
+  }
+}
+
+}  // namespace webrtc