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 | #ifndef RESONANCE_AUDIO_DSP_GAIN_MIXER_H_ |
18 | #define RESONANCE_AUDIO_DSP_GAIN_MIXER_H_ |
19 | |
20 | #include <memory> |
21 | #include <unordered_map> |
22 | #include <vector> |
23 | |
24 | #include "base/audio_buffer.h" |
25 | #include "base/constants_and_types.h" |
26 | #include "dsp/gain_processor.h" |
27 | |
28 | namespace vraudio { |
29 | |
30 | class GainMixer { |
31 | public: |
32 | GainMixer(size_t num_channels, size_t frames_per_buffer); |
33 | |
34 | // Adds a separately scaled version of each channel of the input buffer to the |
35 | // output buffer's corresponding channels. |
36 | // |
37 | // @param input Input buffer to be added. |
38 | // @param gains Gains to be applied to the buffers channels. Must be equal in |
39 | // length to the number of channels in |input|. |
40 | void AddInput(const AudioBuffer& input, const std::vector<float>& gains); |
41 | |
42 | // Adds a single input channel to each of the output buffer's channels, with |
43 | // a separate gain applied to the input channel per output channel. |
44 | // |
45 | // @param input Input channel to be added. |
46 | // @param source_id Identifier corresponding to the input. |
47 | // @param gains Gains to be applied to the buffers channels. Must be equal in |
48 | // length to the number of channels in the output buffer. |
49 | void AddInputChannel(const AudioBuffer::Channel& input, SourceId source_id, |
50 | const std::vector<float>& gains); |
51 | |
52 | // Returns a pointer to the accumulator. |
53 | // |
54 | // @return Pointer to the processed (mixed) output buffer, or nullptr if no |
55 | // input has been added to the accumulator. |
56 | const AudioBuffer* GetOutput() const; |
57 | |
58 | // Resets the state of the accumulator. |
59 | void Reset(); |
60 | |
61 | private: |
62 | // Comprises one |GainProcessor| per channel of a source and a boolean to |
63 | // denote whether that source is active. |
64 | struct GainProcessors { |
65 | explicit GainProcessors(size_t num_channels); |
66 | |
67 | // Bool to signify if a given source is still passing data to a processor. |
68 | bool processors_active; |
69 | |
70 | // Scale and accumulation processors, one per channel for each source. |
71 | std::vector<GainProcessor> processors; |
72 | }; |
73 | |
74 | // Returns the |GainProcessor|s associated with a |source_id| (or creates |
75 | // one if needed) and sets the corresponding |processors_active| flag to true. |
76 | // |
77 | // @param source_id Identifier for a given input. |
78 | // @return The corresponding |ScalingAccumulators|. |
79 | std::vector<GainProcessor>* GetOrCreateProcessors(SourceId source_id); |
80 | |
81 | // Number of channels. |
82 | const size_t num_channels_; |
83 | |
84 | // Output buffer (accumulator). |
85 | AudioBuffer output_; |
86 | |
87 | // Denotes whether the accumulator has processed any inputs or not. |
88 | bool is_empty_; |
89 | |
90 | // Scale and accumulation processors, one per channel for each source. |
91 | std::unordered_map<SourceId, GainProcessors> source_gain_processors_; |
92 | }; |
93 | |
94 | } // namespace vraudio |
95 | |
96 | #endif // RESONANCE_AUDIO_DSP_GAIN_MIXER_H_ |
97 | |