remoting/codec/audio_decoder_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_decoder_speex.h"
   6
   7 #include <string>
   8
   9 #include "base/basictypes.h"
  10 #include "base/memory/scoped_ptr.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 remoting {
  18
  19 namespace {
  20
  21 // Hosts will never generate more than 100 frames in a single packet.
  22 const int kMaxFramesPerPacket = 100;
  23
  24 }  // namespace
  25
  26 AudioDecoderSpeex::AudioDecoderSpeex() {
  27   // Create and initialize the Speex structures.
  28   speex_bits_.reset(new SpeexBits());
  29   speex_bits_init(speex_bits_.get());
  30   speex_state_ = speex_decoder_init(&speex_wb_mode);
  31
  32   // Create and initialize the Speex stereo state.
  33   speex_stereo_state_ = speex_stereo_state_init();
  34
  35   // Create and initialize the stereo callback.
  36   speex_callback_.reset(new SpeexCallback());
  37   speex_callback_->callback_id = SPEEX_INBAND_STEREO;
  38   speex_callback_->func = speex_std_stereo_request_handler;
  39   speex_callback_->data = speex_stereo_state_;
  40
  41   int result;
  42
  43   // Turn on perceptual enhancer, which will make the audio sound better,
  44   // at the price of further distorting the decoded samples.
  45   int enhancer = 1;
  46   result = speex_decoder_ctl(speex_state_, SPEEX_SET_ENH, &enhancer);
  47   CHECK_EQ(result, 0);
  48
  49   // Get the frame size, so that we know the size of output when we decode
  50   // frame by frame.
  51   result = speex_decoder_ctl(speex_state_,
  52                              SPEEX_GET_FRAME_SIZE,
  53                              &speex_frame_size_);
  54   CHECK_EQ(result, 0);
  55
  56   // Set the stereo callback, so that the Speex decoder can get the intensity
  57   // stereo information.
  58   result = speex_decoder_ctl(speex_state_,
  59                              SPEEX_SET_HANDLER,
  60                              speex_callback_.get());
  61   CHECK_EQ(result, 0);
  62 }
  63
  64 AudioDecoderSpeex::~AudioDecoderSpeex() {
  65   speex_stereo_state_destroy(speex_stereo_state_);
  66   speex_decoder_destroy(speex_state_);
  67   speex_bits_destroy(speex_bits_.get());
  68 }
  69
  70 scoped_ptr<AudioPacket> AudioDecoderSpeex::Decode(
  71     scoped_ptr<AudioPacket> packet) {
  72   if ((packet->encoding() != AudioPacket::ENCODING_SPEEX) ||
  73       (packet->bytes_per_sample() != AudioPacket::BYTES_PER_SAMPLE_2) ||
  74       (packet->sampling_rate() == AudioPacket::SAMPLING_RATE_INVALID) ||
  75       (packet->channels() != AudioPacket::CHANNELS_STEREO)) {
  76     LOG(WARNING) << "Received an unsupported packet.";
  77     return scoped_ptr<AudioPacket>();
  78   }
  79   if (packet->data_size() > kMaxFramesPerPacket) {
  80     LOG(WARNING) << "Received an packet with too many frames.";
  81     return scoped_ptr<AudioPacket>();
  82   }
  83
  84   // Create a new packet of decoded data.
  85   scoped_ptr<AudioPacket> decoded_packet(new AudioPacket());
  86   decoded_packet->set_encoding(AudioPacket::ENCODING_RAW);
  87   decoded_packet->set_sampling_rate(packet->sampling_rate());
  88   decoded_packet->set_bytes_per_sample(packet->bytes_per_sample());
  89   decoded_packet->set_channels(packet->channels());
  90
  91   std::string* decoded_data = decoded_packet->add_data();
  92   decoded_data->resize(packet->data_size() *
  93                        speex_frame_size_ *
  94                        packet->bytes_per_sample() *
  95                        packet->channels());
  96   int16* samples = reinterpret_cast<int16*>(string_as_array(decoded_data));
  97
  98   for (int i = 0; i < packet->data_size(); ++i) {
  99     // Read the bytes into the bits structure.
 100     speex_bits_read_from(speex_bits_.get(),
 101                          string_as_array(packet->mutable_data(i)),
 102                          packet->data(i).size());
 103
 104     // Decode the frame and store it in the buffer.
 105     int status = speex_decode_int(speex_state_, speex_bits_.get(), samples);
 106     if (status < 0) {
 107       LOG(ERROR) << "Error in decoding Speex data.";
 108       return scoped_ptr<AudioPacket>();
 109     }
 110     // Transform mono to stereo.
 111     speex_decode_stereo_int(samples, speex_frame_size_, speex_stereo_state_);
 112
 113     samples += (speex_frame_size_ * packet->channels());
 114   }
 115
 116   return decoded_packet.Pass();
 117 }
 118
 119 }  // namespace remoting