Speex encoding/decoding.

remoting/codec/audio_decoder_speex.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/codec/audio_decoder_speex.h"
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "remoting/proto/audio.pb.h"
+#include "third_party/speex/speex.h"
+
+namespace remoting {
+
+AudioDecoderSpeex::AudioDecoderSpeex() {
+  // Create and initialize the Speex structures.
+  speex_bits_.reset(new SpeexBits());
+  speex_bits_init(speex_bits_.get());
+  speex_state_ = speex_decoder_init(&speex_wb_mode);

[Sergey Ulanov, 2012/08/17 21:52:17]

Do we tell speex anywhere that this is a stereo stream?

[kxing, 2012/08/20 21:50:21]

Done.

+
+  // Turn perceptual enhancer.
+  int enhancer = 1;
+  speex_decoder_ctl(speex_state_, SPEEX_SET_ENH, &enhancer);

[Sergey Ulanov, 2012/08/17 21:52:17]

DCHECK here and below to verify that it returns 0.

[kxing, 2012/08/20 21:50:21]

Done.

+
+  // Get the frame size.
+  speex_decoder_ctl(speex_state_, SPEEX_GET_FRAME_SIZE, &speex_frame_size_);
+}
+
+AudioDecoderSpeex::~AudioDecoderSpeex() {
+  speex_decoder_destroy(speex_state_);
+  speex_bits_destroy(speex_bits_.get());
+}
+
+scoped_ptr<AudioPacket> AudioDecoderSpeex::Decode(
+    scoped_ptr<AudioPacket> packet) {
+  if ((packet->encoding() != AudioPacket::ENCODING_SPEEX) ||
+      (packet->bytes_per_sample() != AudioPacket::BYTES_PER_SAMPLE_2)) {
+    LOG(WARNING) << "Received a corrupted packet.";
+    return scoped_ptr<AudioPacket>(NULL);
+  }
+
+  // Create a new packet of decoded data.
+  scoped_ptr<AudioPacket> decoded_packet(new AudioPacket());
+  decoded_packet->set_encoding(AudioPacket::ENCODING_RAW);
+  decoded_packet->set_sampling_rate(packet->sampling_rate());
+  decoded_packet->set_bytes_per_sample(packet->bytes_per_sample());
+  decoded_packet->set_channels(packet->channels());
+
+  std::string* decoded_data = decoded_packet->add_data();
+  decoded_data->resize(
+      packet->data_size() * speex_frame_size_ * packet->bytes_per_sample());
+  int16* samples = reinterpret_cast<int16*>(string_as_array(decoded_data));
+
+  for (int i = 0; i < packet->data_size(); ++i) {
+    // Read the bytes into the bits structure.
+    speex_bits_read_from(speex_bits_.get(),
+                         string_as_array(packet->mutable_data(i)),
+                         packet->data(i).size());
+
+    // Decode the frame and store it in the buffer.
+    int status = speex_decode_int(speex_state_, speex_bits_.get(), samples);
+    if (status < 0) {
+      LOG(ERROR) << "Error in decoding Speex data.";
+      return scoped_ptr<AudioPacket>(NULL);
+    }
+
+    samples += speex_frame_size_;
+  }
+
+  return decoded_packet.Pass();
+}
+
+}  // namespace remoting