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
18 namespace webrtc {
19
PushSincResampler(size_t source_frames,size_t destination_frames)20 PushSincResampler::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
~PushSincResampler()31 PushSincResampler::~PushSincResampler() {
32 }
33
Resample(const int16_t * source,size_t source_length,int16_t * destination,size_t destination_capacity)34 size_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
Resample(const float * source,size_t source_length,float * destination,size_t destination_capacity)49 size_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
Run(size_t frames,float * destination)81 void 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