Speex encoding/decoding.

remoting/codec/audio_encoder_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_encoder_speex.h"
+
+#include <string>
+#include <sstream>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "remoting/proto/audio.pb.h"
+#include "third_party/speex/speex.h"
+
+namespace {
+const int kSpeexQuality = 8;
+}  // namespace
+
+namespace remoting {
+
+AudioEncoderSpeex::AudioEncoderSpeex() {
+  // Create and initialize the Speex structures.
+  speex_bits_init(&speex_bits_);
+  speex_state_ = speex_encoder_init(&speex_wb_mode);
+
+  // Set the encoding quality.
+  int quality = kSpeexQuality;
+  speex_encoder_ctl(speex_state_, SPEEX_SET_QUALITY, &quality);
+
+  // Get the frame size and construct the output buffer accordingly.
+  speex_encoder_ctl(speex_state_, SPEEX_GET_FRAME_SIZE, &speex_frame_size_);
+  buffer_size_ = speex_frame_size_ * sizeof(spx_int16_t);
+  buffer_.reset(new char[buffer_size_]);
+}
+
+AudioEncoderSpeex::~AudioEncoderSpeex() {
+  speex_encoder_destroy(speex_state_);
+  speex_bits_destroy(&speex_bits_);
+}
+
+scoped_ptr<AudioPacket> AudioEncoderSpeex::Encode(
+    scoped_ptr<AudioPacket> packet) {
+  DCHECK_EQ(AudioPacket::ENCODING_RAW, packet->encoding());
+  DCHECK_EQ(AudioPacket::BYTES_PER_SAMPLE_2, packet->bytes_per_sample());
+
+  int number_of_samples = packet->data().size() / sizeof(spx_int16_t);
+  // Either because the Speex encoder modifies the input data buffer,
+  // or the API is not const-correct, we have to convert the packet
+  // payload into a non-const pointer.
+  std::string* data = const_cast<std::string*>(&(packet->data()));
+  spx_int16_t* samples =
+      reinterpret_cast<spx_int16_t*>(string_as_array(data));
+
+  std::string encoded_data;
+
+  for (int i = 0; i < number_of_samples; i += speex_frame_size_) {
+    // Reset the bits structure for this frame.
+    speex_bits_reset(&speex_bits_);
+
+    // Encode the frame, treating all samples as integers.
+    speex_encode_int(speex_state_, samples + i, &speex_bits_);
+
+    // Sanity check to prevent overwriting the buffer.
+    if (speex_bits_nbytes(&speex_bits_) >= buffer_size_) {
+      LOG(ERROR) << "Speex encoder is not compressing data.";

[Sergey Ulanov, 2012/08/10 20:41:37]

WARNING?

[kxing, 2012/08/13 21:39:45]

Done.

+      buffer_size_ = speex_bits_nbytes(&speex_bits_);
+      buffer_.reset(new char[buffer_size_]);
+    }
+
+    // Copy the encoded data from the bits structure into the buffer.
+    int bytes_written =
+        speex_bits_write(&speex_bits_, buffer_.get(), buffer_size_);
+
+    // Write out the data as the data size followed by the encoded data.
+    // The data size is an unsigned int8 so we can support sizes up to 256
+    // bytes.
+    DCHECK_LE(bytes_written, 0xFF);
+    uint8 bytes_written_as_byte = static_cast<uint8>(bytes_written);
+    encoded_data.append(reinterpret_cast<char*>(&bytes_written_as_byte),
+                        sizeof(uint8));
+    encoded_data.append(buffer_.get(), bytes_written);
+  }
+
+  // Create a new packet of encoded data.
+  scoped_ptr<AudioPacket> encoded_packet(new AudioPacket());
+  encoded_packet->set_data(encoded_data);

[Sergey Ulanov, 2012/08/10 20:41:37]

To avoid copying it here it's better to allocate encoded_packet first and store
encoded data directly in it.

[kxing, 2012/08/13 21:39:45]

Done.

+  encoded_packet->set_encoding(AudioPacket::ENCODING_SPEEX);
+  encoded_packet->set_sampling_rate(packet->sampling_rate());
+  encoded_packet->set_bytes_per_sample(packet->bytes_per_sample());
+  encoded_packet->set_channels(packet->channels());
+  return encoded_packet.Pass();
+}
+
+}  // namespace remoting