1 | /* |
2 | Copyright 2018 Google Inc. All Rights Reserved. |
3 | |
4 | Licensed under the Apache License, Version 2.0 (the "License"); |
5 | you may not use this file except in compliance with the License. |
6 | You may obtain a copy of the License at |
7 | |
8 | http://www.apache.org/licenses/LICENSE-2.0 |
9 | |
10 | Unless required by applicable law or agreed to in writing, software |
11 | distributed under the License is distributed on an "AS-IS" BASIS, |
12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | See the License for the specific language governing permissions and |
14 | limitations under the License. |
15 | */ |
16 | |
17 | #include "utils/buffer_crossfader.h" |
18 | |
19 | #include "base/constants_and_types.h" |
20 | #include "base/simd_utils.h" |
21 | |
22 | namespace vraudio { |
23 | |
24 | BufferCrossfader::BufferCrossfader(size_t num_frames) |
25 | : crossfade_buffer_(kNumStereoChannels, num_frames) { |
26 | DCHECK_NE(num_frames, 0); |
27 | // Initialize the |crossfade_buffer_|. |
28 | auto* fade_in_channel = &crossfade_buffer_[0]; |
29 | auto* fade_out_channel = &crossfade_buffer_[1]; |
30 | for (size_t frame = 0; frame < num_frames; ++frame) { |
31 | const float crossfade_factor = |
32 | static_cast<float>(frame) / static_cast<float>(num_frames); |
33 | (*fade_in_channel)[frame] = crossfade_factor; |
34 | (*fade_out_channel)[frame] = 1.0f - crossfade_factor; |
35 | } |
36 | } |
37 | |
38 | void BufferCrossfader::ApplyLinearCrossfade(const AudioBuffer& input_fade_in, |
39 | const AudioBuffer& input_fade_out, |
40 | AudioBuffer* output) const { |
41 | DCHECK(output); |
42 | DCHECK_NE(output, &input_fade_in); |
43 | DCHECK_NE(output, &input_fade_out); |
44 | |
45 | const size_t num_channels = input_fade_in.num_channels(); |
46 | const size_t num_frames = input_fade_in.num_frames(); |
47 | DCHECK_EQ(num_channels, input_fade_out.num_channels()); |
48 | DCHECK_EQ(num_channels, output->num_channels()); |
49 | DCHECK_EQ(num_frames, input_fade_out.num_frames()); |
50 | DCHECK_EQ(num_frames, output->num_frames()); |
51 | DCHECK_EQ(num_frames, crossfade_buffer_.num_frames()); |
52 | |
53 | const auto* gain_fade_in_channel = crossfade_buffer_[0].begin(); |
54 | const auto* gain_fade_out_channel = crossfade_buffer_[1].begin(); |
55 | for (size_t channel = 0; channel < num_channels; ++channel) { |
56 | const auto* input_fade_in_channel = input_fade_in[channel].begin(); |
57 | const auto* input_fade_out_channel = input_fade_out[channel].begin(); |
58 | auto* output_channel = ((*output)[channel]).begin(); |
59 | MultiplyPointwise(length: num_frames, input_a: gain_fade_in_channel, input_b: input_fade_in_channel, |
60 | output: output_channel); |
61 | MultiplyAndAccumulatePointwise(length: num_frames, input_a: gain_fade_out_channel, |
62 | input_b: input_fade_out_channel, accumulator: output_channel); |
63 | } |
64 | } |
65 | |
66 | } // namespace vraudio |
67 | |