1/*
2Copyright 2018 Google Inc. All Rights Reserved.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8 http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS-IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17#include "dsp/gain.h"
18
19#include "base/constants_and_types.h"
20#include "base/simd_macros.h"
21#include "base/simd_utils.h"
22
23namespace vraudio {
24
25float LinearGainRamp(size_t ramp_length, float start_gain, float end_gain,
26 const AudioBuffer::Channel& input_samples,
27 AudioBuffer::Channel* output_samples,
28 bool accumulate_output) {
29 DCHECK(output_samples);
30 DCHECK_EQ(input_samples.size(), output_samples->size());
31 DCHECK_GT(ramp_length, 0U);
32
33 const size_t process_length = std::min(a: ramp_length, b: input_samples.size());
34 const float gain_increment_per_sample =
35 (end_gain - start_gain) / static_cast<float>(ramp_length);
36
37 float current_gain = start_gain;
38 if (accumulate_output) {
39 for (size_t frame = 0; frame < process_length; ++frame) {
40 (*output_samples)[frame] += current_gain * input_samples[frame];
41 current_gain += gain_increment_per_sample;
42 }
43 } else {
44 for (size_t frame = 0; frame < process_length; ++frame) {
45 (*output_samples)[frame] = current_gain * input_samples[frame];
46 current_gain += gain_increment_per_sample;
47 }
48 }
49
50 return current_gain;
51}
52
53void ConstantGain(size_t offset_index, float gain,
54 const AudioBuffer::Channel& input_samples,
55 AudioBuffer::Channel* output_samples,
56 bool accumulate_output) {
57 DCHECK(output_samples);
58 const size_t input_size = input_samples.size();
59 DCHECK_EQ(input_size, output_samples->size());
60 DCHECK_LT(offset_index, input_size);
61
62 // Apply gain to samples at the beginning, prior to SIMD_LENGTH alignment.
63 const size_t unaligned_samples = SIMD_LENGTH - (offset_index % SIMD_LENGTH);
64 const size_t offset_index_simd =
65 std::min(a: input_size, b: offset_index + unaligned_samples);
66 if (accumulate_output) {
67 for (size_t i = offset_index; i < offset_index_simd; ++i) {
68 (*output_samples)[i] += input_samples[i] * gain;
69 }
70 } else {
71 for (size_t i = offset_index; i < offset_index_simd; ++i) {
72 (*output_samples)[i] = input_samples[i] * gain;
73 }
74 }
75
76 if (offset_index_simd == input_size) {
77 // Return if there are no remaining operations to carry out.
78 return;
79 }
80
81 const size_t aligned_length = input_size - offset_index_simd;
82 const float* aligned_input = &(input_samples[offset_index_simd]);
83 float* aligned_output = &(*output_samples)[offset_index_simd];
84
85 // Apply gain via SIMD operations.
86 if (accumulate_output) {
87 ScalarMultiplyAndAccumulate(length: aligned_length, gain, input: aligned_input,
88 accumulator: aligned_output);
89 } else {
90 ScalarMultiply(length: aligned_length, gain, input: aligned_input, output: aligned_output);
91 }
92}
93
94bool IsGainNearZero(float gain) {
95 return std::abs(x: gain) < kNegative60dbInAmplitude;
96}
97
98bool IsGainNearUnity(float gain) {
99 return std::abs(x: 1.0f - gain) < kNegative60dbInAmplitude;
100}
101
102} // namespace vraudio
103

source code of qtmultimedia/src/3rdparty/resonance-audio/resonance_audio/dsp/gain.cc