1 /*
2  * Copyright 2020 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 package org.hyphonate.megaaudio.player;
17 
18 public abstract class AudioSource {
AudioSource()19     public AudioSource() {}
20 
21     /**
22      * Called before the stream starts to allow initialization of the source
23      * @param numFrames The number of frames that will be requested in each pull() call.
24      * @param numChans The number of channels in the stream.
25      */
init(int numFrames, int numChans)26     public void init(int numFrames, int numChans) {}
27 
28     // This may be relevant to concrete classes which produce a sound with a notion of pitch
setSampleRate(int sampleRate)29     public void setSampleRate(int sampleRate) {}
30 
31     /**
32      * (for period sources) sets the frequency of the signal
33      * @param freq
34      */
setFreq(float freq)35     public void setFreq(float freq) {}
36 
start()37     public void start() {}
stop()38     public void stop() {}
39 
40     /**
41      * reset a stream to the beginning.
42      */
reset()43     public void reset() {}
44 
45     /**
46      * triggers some event in the AudioSource. Whatever that event is is up to the AudioSource
47      * subclass.
48      */
trigger()49     public void trigger() {}
50 
51     /**
52      * Process a request for audio data.
53      * @param audioData The buffer to be filled.
54      * @param numFrames The number of frames of audio to provide.
55      * @param numChans The number of channels (in the buffer) required by the player.
56      * @return The number of frames actually generated. If this value is less than that
57      * requested, it may be interpreted by the player as the end of playback.
58      * Note that the player will be blocked by this call.
59      * Note that the data is assumed to be *interleaved*.
60      */
pull(float[] audioData, int numFrames, int numChans)61     public abstract int pull(float[] audioData, int numFrames, int numChans);
62 }
63