content/browser/speech/audio_buffer.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 "content/browser/speech/audio_buffer.h"
   6
   7 #include "base/logging.h"
   8 #include "base/stl_util.h"
   9
  10 namespace content {
  11
  12 AudioChunk::AudioChunk(int bytes_per_sample)
  13     : bytes_per_sample_(bytes_per_sample) {
  14 }
  15
  16 AudioChunk::AudioChunk(const uint8* data, size_t length, int bytes_per_sample)
  17     : data_string_(reinterpret_cast<const char*>(data), length),
  18       bytes_per_sample_(bytes_per_sample) {
  19   DCHECK_EQ(length % bytes_per_sample, 0U);
  20 }
  21
  22 bool AudioChunk::IsEmpty() const {
  23   return data_string_.empty();
  24 }
  25
  26 size_t AudioChunk::NumSamples() const {
  27   return data_string_.size() / bytes_per_sample_;
  28 }
  29
  30 const std::string& AudioChunk::AsString() const {
  31   return data_string_;
  32 }
  33
  34 int16 AudioChunk::GetSample16(size_t index) const {
  35   DCHECK(index < (data_string_.size() / sizeof(int16)));
  36   return SamplesData16()[index];
  37 }
  38
  39 const int16* AudioChunk::SamplesData16() const {
  40   return reinterpret_cast<const int16*>(data_string_.data());
  41 }
  42
  43
  44 AudioBuffer::AudioBuffer(int bytes_per_sample)
  45     : bytes_per_sample_(bytes_per_sample) {
  46   DCHECK(bytes_per_sample == 1 ||
  47          bytes_per_sample == 2 ||
  48          bytes_per_sample == 4);
  49 }
  50
  51 AudioBuffer::~AudioBuffer() {
  52   Clear();
  53 }
  54
  55 void AudioBuffer::Enqueue(const uint8* data, size_t length) {
  56   chunks_.push_back(new AudioChunk(data, length, bytes_per_sample_));
  57 }
  58
  59 scoped_refptr<AudioChunk> AudioBuffer::DequeueSingleChunk() {
  60   DCHECK(!chunks_.empty());
  61   scoped_refptr<AudioChunk> chunk(chunks_.front());
  62   chunks_.pop_front();
  63   return chunk;
  64 }
  65
  66 scoped_refptr<AudioChunk> AudioBuffer::DequeueAll() {
  67   scoped_refptr<AudioChunk> chunk(new AudioChunk(bytes_per_sample_));
  68   size_t resulting_length = 0;
  69   ChunksContainer::const_iterator it;
  70   // In order to improve performance, calulate in advance the total length
  71   // and then copy the chunks.
  72   for (it = chunks_.begin(); it != chunks_.end(); ++it) {
  73     resulting_length += (*it)->data_string_.length();
  74   }
  75   chunk->data_string_.reserve(resulting_length);
  76   for (it = chunks_.begin(); it != chunks_.end(); ++it) {
  77     chunk->data_string_.append((*it)->data_string_);
  78   }
  79   Clear();
  80   return chunk;
  81 }
  82
  83 void AudioBuffer::Clear() {
  84   chunks_.clear();
  85 }
  86
  87 bool AudioBuffer::IsEmpty() const {
  88   return chunks_.empty();
  89 }
  90
  91 }  // namespace content