remoting/codec/audio_encoder_speex.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "remoting/codec/audio_encoder_speex.h"
   6
   7 #include <string>
   8 #include <sstream>
   9
  10 #include "base/basictypes.h"
  11 #include "base/logging.h"
  12 #include "base/stl_util.h"
  13 #include "remoting/proto/audio.pb.h"
  14 #include "third_party/speex/include/speex/speex_callbacks.h"
  15 #include "third_party/speex/include/speex/speex_stereo.h"
  16
  17 namespace {
  18 // A quality of 8 in wide band mode corresponds to 27,800 bits per second.
  19 const int kSpeexHighQuality = 8;
  20 const int kEncodedDataBufferSize = 0xFF;
  21 }  // namespace
  22
  23 namespace remoting {
  24
  25 AudioEncoderSpeex::AudioEncoderSpeex()
  26     : leftover_frames_(0) {
  27   // Create and initialize the Speex structures.
  28   speex_bits_.reset(new SpeexBits());
  29   speex_bits_init(speex_bits_.get());
  30   speex_state_ = speex_encoder_init(&speex_wb_mode);
  31
  32   // Set the encoding quality.
  33   int quality = kSpeexHighQuality;
  34   speex_encoder_ctl(speex_state_, SPEEX_SET_QUALITY, &quality);
  35
  36   // Get the frame size and construct the input buffer accordingly.
  37   int result = speex_encoder_ctl(speex_state_,
  38                                  SPEEX_GET_FRAME_SIZE,
  39                                  &speex_frame_size_);
  40   CHECK_EQ(result, 0);
  41
  42   leftover_buffer_.reset(
  43       new int16[speex_frame_size_ * AudioPacket::CHANNELS_STEREO]);
  44 }
  45
  46 AudioEncoderSpeex::~AudioEncoderSpeex() {
  47   speex_encoder_destroy(speex_state_);
  48   speex_bits_destroy(speex_bits_.get());
  49 }
  50
  51 scoped_ptr<AudioPacket> AudioEncoderSpeex::Encode(
  52     scoped_ptr<AudioPacket> packet) {
  53   DCHECK_EQ(AudioPacket::ENCODING_RAW, packet->encoding());
  54   DCHECK_EQ(1, packet->data_size());
  55   DCHECK_EQ(AudioPacket::BYTES_PER_SAMPLE_2, packet->bytes_per_sample());
  56   DCHECK_NE(AudioPacket::SAMPLING_RATE_INVALID, packet->sampling_rate());
  57   DCHECK_EQ(AudioPacket::CHANNELS_STEREO, packet->channels());
  58
  59   int frames_left =
  60       packet->data(0).size() / packet->bytes_per_sample() / packet->channels();
  61   const int16* next_sample =
  62       reinterpret_cast<const int16*>(packet->data(0).data());
  63
  64   // Create a new packet of encoded data.
  65   scoped_ptr<AudioPacket> encoded_packet(new AudioPacket());
  66   encoded_packet->set_encoding(AudioPacket::ENCODING_SPEEX);
  67   encoded_packet->set_sampling_rate(packet->sampling_rate());
  68   encoded_packet->set_bytes_per_sample(packet->bytes_per_sample());
  69   encoded_packet->set_channels(packet->channels());
  70
  71   while (leftover_frames_ + frames_left >= speex_frame_size_) {
  72     int16* unencoded_buffer = NULL;
  73     int frames_consumed = 0;
  74
  75     if (leftover_frames_ > 0) {
  76       unencoded_buffer = leftover_buffer_.get();
  77       frames_consumed = speex_frame_size_ - leftover_frames_;
  78
  79       memcpy(leftover_buffer_.get() + leftover_frames_ * packet->channels(),
  80              next_sample,
  81              frames_consumed * packet->bytes_per_sample() * packet->channels());
  82
  83       leftover_frames_ = 0;
  84     } else {
  85       unencoded_buffer = const_cast<int16*>(next_sample);
  86       frames_consumed = speex_frame_size_;
  87     }
  88
  89     // Transform stereo to mono.
  90     speex_encode_stereo_int(unencoded_buffer,
  91                             speex_frame_size_,
  92                             speex_bits_.get());
  93
  94     // Encode the frame, treating all samples as integers.
  95     speex_encode_int(speex_state_,
  96                      unencoded_buffer,
  97                      speex_bits_.get());
  98
  99     next_sample += frames_consumed * packet->channels();
 100     frames_left -= frames_consumed;
 101
 102     std::string* new_data = encoded_packet->add_data();
 103     new_data->resize(speex_bits_nbytes(speex_bits_.get()));
 104
 105     // Copy the encoded data from the bits structure into the buffer.
 106     int bytes_written = speex_bits_write(speex_bits_.get(),
 107                                          string_as_array(new_data),
 108                                          new_data->size());
 109
 110     // Expect that the bytes are all written.
 111     DCHECK_EQ(bytes_written, static_cast<int>(new_data->size()));
 112
 113     // Reset the bits structure for this frame.
 114     speex_bits_reset(speex_bits_.get());
 115   }
 116
 117   // Store the leftover samples.
 118   if (frames_left > 0) {
 119     CHECK_LE(leftover_frames_ + frames_left, speex_frame_size_);
 120     memcpy(leftover_buffer_.get() + leftover_frames_ * packet->channels(),
 121            next_sample,
 122            frames_left * packet->bytes_per_sample() * packet->channels());
 123     leftover_frames_ += frames_left;
 124   }
 125
 126   // Return NULL if there's nothing in the packet.
 127   if (encoded_packet->data_size() == 0)
 128     return scoped_ptr<AudioPacket>();
 129
 130   return encoded_packet.Pass();
 131 }
 132
 133 }  // namespace remoting