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;
+const int kEncodedDataBufferSize = 0xFF;
+}  // namespace
+
+namespace remoting {
+
+AudioEncoderSpeex::AudioEncoderSpeex()
+    : leftover_samples_(0) {
+  // Create and initialize the Speex structures.
+  speex_bits_.reset(new SpeexBits());
+  speex_bits_init(speex_bits_.get());
+  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 input buffer accordingly.
+  speex_encoder_ctl(speex_state_, SPEEX_GET_FRAME_SIZE, &speex_frame_size_);
+  raw_data_buffer_.reset(new int16[speex_frame_size_]);
+}
+
+AudioEncoderSpeex::~AudioEncoderSpeex() {
+  speex_encoder_destroy(speex_state_);
+  speex_bits_destroy(speex_bits_.get());
+}
+
+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());
+  DCHECK_EQ(1, packet->data_size());
+
+  // Put the samples onto the queue.
+  int samples_left = packet->data(0).size() / packet->bytes_per_sample();

[Sergey Ulanov, 2012/08/17 21:52:18]

This is not correct because we normally have two channels. It looks to me that
you are encoding samples from two channels is if they are one channel. 
I think you need to use  speex_decode_stereo_int() and 
speex_encode_stereo_int() in order to encode/decode stereo stream

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

Done.

+  const int16* next_sample =
+      reinterpret_cast<const int16*>(packet->data(0).data());
+
+  // Create a new packet of encoded data.
+  scoped_ptr<AudioPacket> encoded_packet(new AudioPacket());
+  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());
+
+  while (leftover_samples_ + samples_left >= speex_frame_size_) {
+    if (leftover_samples_ > 0) {
+      int samples_needed = speex_frame_size_ - leftover_samples_;
+
+      memcpy(raw_data_buffer_.get() + leftover_samples_,
+             next_sample,
+             packet->bytes_per_sample() * samples_needed);
+
+      // Encode the frame, treating all samples as integers.
+      speex_encode_int(speex_state_, raw_data_buffer_.get(), speex_bits_.get());
+
+      leftover_samples_ = 0;
+      next_sample += samples_needed;
+      samples_left -= samples_needed;
+    } else {
+      // Encode the frame, treating all samples as integers.
+      speex_encode_int(speex_state_,
+                       const_cast<int16*>(next_sample),
+                       speex_bits_.get());
+    }
+
+    std::string* new_data = encoded_packet->add_data();
+    new_data->resize(speex_bits_nbytes(speex_bits_.get()));
+
+    // Copy the encoded data from the bits structure into the buffer.
+    int bytes_written = speex_bits_write(speex_bits_.get(),
+                                         string_as_array(new_data),
+                                         new_data->size());
+
+    // Expect that the bytes are all written.
+    DCHECK_EQ(bytes_written, static_cast<int>(new_data->size()));
+
+    next_sample += speex_frame_size_;
+    samples_left -= speex_frame_size_;
+
+    // Reset the bits structure for this frame.
+    speex_bits_reset(speex_bits_.get());
+  }
+
+  // Store the leftover samples.
+  if (samples_left > 0) {
+    memcpy(raw_data_buffer_.get() + leftover_samples_,

[Sergey Ulanov, 2012/08/17 21:52:18]

Need to verify that there is always space in the buffer. Add
CHECK_LE(lefover_samples + samples_left, speex_frame_size_);

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

Done.

+           next_sample,
+           packet->bytes_per_sample() * samples_left);
+    leftover_samples_ += samples_left;
+  }
+
+  return encoded_packet.Pass();
+}
+
+}  // namespace remoting