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#ifndef RESONANCE_AUDIO_DSP_CIRCULAR_BUFFER_H_
18#define RESONANCE_AUDIO_DSP_CIRCULAR_BUFFER_H_
19
20#include "base/audio_buffer.h"
21
22namespace vraudio {
23// Class that implements a simple mono circular buffer, accepting input and
24// output of different length.
25class CircularBuffer {
26 public:
27 // Constructs a circular buffer.
28 //
29 // @param buffer_length The length of the Circular buffer. This value must be
30 // at least |num_input_frames| + |num_output_frames| so that we can always
31 // either add or remove data.
32 // @param num_input_frames Length of the input buffers in frames.
33 // @param num_output_frames Length of the output buffers in frames.
34 CircularBuffer(size_t buffer_length, size_t num_input_frames,
35 size_t num_output_frames);
36
37 // Inserts a buffer of mono input into the |CircularBuffer| if space permits.
38 //
39 // @param input A channel of input data |num_input_frames| in length.
40 // @return True if there was space in the buffer and the input was
41 // successfully inserted, false otherwise.
42 bool InsertBuffer(const AudioBuffer::Channel& input);
43
44 // Retrieves a buffer of output from the |CircularBuffer| if it contains
45 // sufficient data.
46 //
47 // @param output A channel to hold |num_output_frames| of output data. The
48 // channel may be greater in length than |num_output_frames|, in this
49 // case only the first |num_output_frames| will be overwritten.
50 // @return True if there was sufficient data in the buffer and the output was
51 // successfully retrieved.
52 bool RetrieveBuffer(AudioBuffer::Channel* output);
53
54 // Retrieves a buffer of output from the |CircularBuffer| to an offset
55 // location in an output channel, provided it contains sufficient data.
56 //
57 // @param offset Number of samples of offset into the |output| channel.
58 // @param output A channel to hold |num_output_frames| of output data. The
59 // channel may be greater in length than |num_output_frames| + |offset|,
60 // in this case only the first |num_output_frames| after |offset| will be
61 // overwritten.
62 // @return True if there was sufficient data in the buffer and the output was
63 // successfully retrieved.
64 bool RetrieveBufferWithOffset(size_t offset, AudioBuffer::Channel* output);
65
66 // Returns the number of samples of data currently in the |CircularBuffer|.
67 //
68 // @return The number of samples of data currently in the buffer.
69 size_t GetOccupancy() const { return num_valid_frames_; }
70
71 // Resets the |CircularBuffer|.
72 void Clear();
73
74 private:
75 // Number of input frames to be inserted into the buffer.
76 const size_t num_input_frames_;
77
78 // Number of output frames to be retrieved from the buffer.
79 const size_t num_output_frames_;
80
81 // Mono audio buffer to hold the data.
82 AudioBuffer buffer_;
83
84 // Position at which we are writing into the buffer.
85 size_t write_cursor_;
86
87 // position at which we are reading from the buffer.
88 size_t read_cursor_;
89
90 // Number of frames of data currently stored within the buffer.
91 size_t num_valid_frames_;
92};
93
94} // namespace vraudio
95
96#endif // RESONANCE_AUDIO_DSP_CIRCULAR_BUFFER_H_
97

source code of qtmultimedia/src/3rdparty/resonance-audio/resonance_audio/dsp/circular_buffer.h