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1 /*
2  * Copyright (C) 2017 The Android Open Source Project
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 LB2_SOUND_SYSTEM_H_
18 #define LB2_SOUND_SYSTEM_H_
19 
20 #include <functional>
21 
22 #include "lb2/audio_buffer.h"
23 #include "lb2/test_context.h"  // for PerformanceMode
24 
25 // Interface for sound systems.
26 // It is assumed that "pull" model (callback) is used for providing
27 // sound data to the system, and "push" model (sync read) is used
28 // for sound input.
29 class SoundSystem {
30   public:
31     // The memory region pointed by this buffer must remain
32     // valid until the write callback is called the next time,
33     // or until 'shutdown' is called.
34     using WriteCallback = std::function<AudioBufferView<sample_t>(size_t expectedFrames)>;
35 
36     SoundSystem() = default;
37     SoundSystem(const SoundSystem&) = delete;
38     SoundSystem& operator=(const SoundSystem&) = delete;
~SoundSystem()39     virtual ~SoundSystem() {}
40 
41     // Probes the output hardware for the recommended parameters for input
42     // and output streams. Returns 'false' if probing is impossible or has failed.
43     // Note that this is a separate use case for the sound system. After commencing
44     // probing, the instance of the sound system used for probing must be shut down.
probeDefaultSettings(PerformanceMode,int *,int *,int *)45     virtual bool probeDefaultSettings(PerformanceMode /*performanceMode*/, int* /*samplingRate*/,
46             int* /*playerBufferFrameCount*/, int* /*recorderBufferFrameCount*/) { return false; }
47     // Initializes the sound system for the regular testing scenario.
48     // Returns 'true' if initialization was successful, 'false' otherwise.
49     virtual bool init(WriteCallback callback) = 0;
50     // Make sure the buffer of the input stream is empty, so fresh audio data
51     // can be received immediately on the next call to 'readAudio'.
52     // Returns 'true' if there were no errors, 'false' otherwise.
53     virtual bool drainInput() = 0;
54     // Reads from audio input into the provided buffer. A non-negative result value
55     // indicates success, a negative return value indicates an error.
56     virtual ssize_t readAudio(AudioBufferView<sample_t> buffer) = 0;
57     // Shuts the sound system down.
58     virtual void shutdown() = 0;
59 };
60 
61 #endif  // LB2_SOUND_SYSTEM_H_
62