1/*
2 *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#include "webrtc/common_audio/resampler/push_sinc_resampler.h"
12
13#include <cstring>
14
15#include "webrtc/base/checks.h"
16#include "webrtc/common_audio/include/audio_util.h"
17
18namespace webrtc {
19
20PushSincResampler::PushSincResampler(size_t source_frames,
21                                     size_t destination_frames)
22    : resampler_(new SincResampler(source_frames * 1.0 / destination_frames,
23                                   source_frames,
24                                   this)),
25      source_ptr_(nullptr),
26      source_ptr_int_(nullptr),
27      destination_frames_(destination_frames),
28      first_pass_(true),
29      source_available_(0) {}
30
31PushSincResampler::~PushSincResampler() {
32}
33
34size_t PushSincResampler::Resample(const int16_t* source,
35                                   size_t source_length,
36                                   int16_t* destination,
37                                   size_t destination_capacity) {
38  if (!float_buffer_.get())
39    float_buffer_.reset(new float[destination_frames_]);
40
41  source_ptr_int_ = source;
42  // Pass nullptr as the float source to have Run() read from the int16 source.
43  Resample(nullptr, source_length, float_buffer_.get(), destination_frames_);
44  FloatS16ToS16(float_buffer_.get(), destination_frames_, destination);
45  source_ptr_int_ = nullptr;
46  return destination_frames_;
47}
48
49size_t PushSincResampler::Resample(const float* source,
50                                   size_t source_length,
51                                   float* destination,
52                                   size_t destination_capacity) {
53  RTC_CHECK_EQ(source_length, resampler_->request_frames());
54  RTC_CHECK_GE(destination_capacity, destination_frames_);
55  // Cache the source pointer. Calling Resample() will immediately trigger
56  // the Run() callback whereupon we provide the cached value.
57  source_ptr_ = source;
58  source_available_ = source_length;
59
60  // On the first pass, we call Resample() twice. During the first call, we
61  // provide dummy input and discard the output. This is done to prime the
62  // SincResampler buffer with the correct delay (half the kernel size), thereby
63  // ensuring that all later Resample() calls will only result in one input
64  // request through Run().
65  //
66  // If this wasn't done, SincResampler would call Run() twice on the first
67  // pass, and we'd have to introduce an entire |source_frames| of delay, rather
68  // than the minimum half kernel.
69  //
70  // It works out that ChunkSize() is exactly the amount of output we need to
71  // request in order to prime the buffer with a single Run() request for
72  // |source_frames|.
73  if (first_pass_)
74    resampler_->Resample(resampler_->ChunkSize(), destination);
75
76  resampler_->Resample(destination_frames_, destination);
77  source_ptr_ = nullptr;
78  return destination_frames_;
79}
80
81void PushSincResampler::Run(size_t frames, float* destination) {
82  // Ensure we are only asked for the available samples. This would fail if
83  // Run() was triggered more than once per Resample() call.
84  RTC_CHECK_EQ(source_available_, frames);
85
86  if (first_pass_) {
87    // Provide dummy input on the first pass, the output of which will be
88    // discarded, as described in Resample().
89    std::memset(destination, 0, frames * sizeof(*destination));
90    first_pass_ = false;
91    return;
92  }
93
94  if (source_ptr_) {
95    std::memcpy(destination, source_ptr_, frames * sizeof(*destination));
96  } else {
97    for (size_t i = 0; i < frames; ++i)
98      destination[i] = static_cast<float>(source_ptr_int_[i]);
99  }
100  source_available_ -= frames;
101}
102
103}  // namespace webrtc
104