1# 使用AudioCapturer开发音频录制功能
2
3AudioCapturer是音频采集器，用于录制PCM（Pulse Code Modulation）音频数据，适合有音频开发经验的开发者实现更灵活的录制功能。
4
5## 开发指导
6
7使用AudioCapturer录制音频涉及到AudioCapturer实例的创建、音频采集参数的配置、采集的开始与停止、资源的释放等。本开发指导将以一次录制音频数据的过程为例，向开发者讲解如何使用AudioCapturer进行音频录制，建议搭配[AudioCapturer的API说明](../../reference/apis-audio-kit/js-apis-audio.md#audiocapturer8)阅读。
8
9下图展示了AudioCapturer的状态变化，在创建实例后，调用对应的方法可以进入指定的状态实现对应的行为。需要注意的是在确定的状态执行不合适的方法可能导致AudioCapturer发生错误，建议开发者在调用状态转换的方法前进行状态检查，避免程序运行产生预期以外的结果。
10
11**图1** AudioCapturer状态变化示意图
12
13![AudioCapturer status change](figures/audiocapturer-status-change.png)
14
15使用on('stateChange')方法可以监听AudioCapturer的状态变化，每个状态对应值与说明见[AudioState](../../reference/apis-audio-kit/js-apis-audio.md#audiostate8)。
16
17### 开发步骤及注意事项
18
191. 配置音频采集参数并创建AudioCapturer实例，音频采集参数的详细信息可以查看[AudioCapturerOptions](../../reference/apis-audio-kit/js-apis-audio.md#audiocaptureroptions8)。
20
21   > **说明：**
22   > 当设置Mic音频源（即[SourceType](../../reference/apis-audio-kit/js-apis-audio.md#sourcetype8)为SOURCE_TYPE_MIC、SOURCE_TYPE_VOICE_RECOGNITION、SOURCE_TYPE_VOICE_COMMUNICATION、SOURCE_TYPE_VOICE_MESSAGE）时，需要申请麦克风权限ohos.permission.MICROPHONE，申请方式参考：[向用户申请授权](../../security/AccessToken/request-user-authorization.md)。
23
24   ```ts
25    import { audio } from '@kit.AudioKit';
26
27    let audioStreamInfo: audio.AudioStreamInfo = {
28      samplingRate: audio.AudioSamplingRate.SAMPLE_RATE_48000, // 采样率
29      channels: audio.AudioChannel.CHANNEL_2, // 通道
30      sampleFormat: audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE, // 采样格式
31      encodingType: audio.AudioEncodingType.ENCODING_TYPE_RAW // 编码格式
32    };
33
34    let audioCapturerInfo: audio.AudioCapturerInfo = {
35      source: audio.SourceType.SOURCE_TYPE_MIC,
36      capturerFlags: 0
37    };
38
39    let audioCapturerOptions: audio.AudioCapturerOptions = {
40      streamInfo: audioStreamInfo,
41      capturerInfo: audioCapturerInfo
42    };
43
44    audio.createAudioCapturer(audioCapturerOptions, (err, data) => {
45      if (err) {
46        console.error(`Invoke createAudioCapturer failed, code is ${err.code}, message is ${err.message}`);
47      } else {
48        console.info('Invoke createAudioCapturer succeeded.');
49        let audioCapturer = data;
50      }
51    });
52   ```
53
542. 调用on('readData')方法，订阅监听音频数据读入回调。
55
56   ```ts
57    import { BusinessError } from '@kit.BasicServicesKit';
58    import { fileIo as fs } from '@kit.CoreFileKit';
59
60    class Options {
61      offset?: number;
62      length?: number;
63    }
64
65    let bufferSize: number = 0;
66    let path = getContext().cacheDir;
67    let filePath = path + '/StarWars10s-2C-48000-4SW.pcm';
68    let file: fs.File = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
69    let readDataCallback = (buffer: ArrayBuffer) => {
70      let options: Options = {
71        offset: bufferSize,
72        length: buffer.byteLength
73      }
74      fs.writeSync(file.fd, buffer, options);
75      bufferSize += buffer.byteLength;
76    };
77
78    audioCapturer.on('readData', readDataCallback);
79   ```
80
813. 调用start()方法进入running状态，开始录制音频。
82
83   ```ts
84    import { BusinessError } from '@kit.BasicServicesKit';
85
86    audioCapturer.start((err: BusinessError) => {
87      if (err) {
88        console.error(`Capturer start failed, code is ${err.code}, message is ${err.message}`);
89      } else {
90        console.info('Capturer start success.');
91      }
92    });
93   ```
94
954. 调用stop()方法停止录制。
96
97   ```ts
98    import { BusinessError } from '@kit.BasicServicesKit';
99
100    audioCapturer.stop((err: BusinessError) => {
101      if (err) {
102        console.error(`Capturer stop failed, code is ${err.code}, message is ${err.message}`);
103      } else {
104        console.info('Capturer stopped.');
105      }
106    });
107   ```
108
1095. 调用release()方法销毁实例，释放资源。
110
111   ```ts
112    import { BusinessError } from '@kit.BasicServicesKit';
113
114    audioCapturer.release((err: BusinessError) => {
115      if (err) {
116        console.error(`capturer release failed, code is ${err.code}, message is ${err.message}`);
117      } else {
118        console.info('capturer released.');
119      }
120    });
121   ```
122
123### 完整示例
124
125下面展示了使用AudioCapturer录制音频的完整示例代码。
126
127```ts
128import { audio } from '@kit.AudioKit';
129import { BusinessError } from '@kit.BasicServicesKit';
130import { fileIo as fs } from '@kit.CoreFileKit';
131
132const TAG = 'AudioCapturerDemo';
133
134class Options {
135  offset?: number;
136  length?: number;
137}
138
139let bufferSize: number = 0;
140let audioCapturer: audio.AudioCapturer | undefined = undefined;
141let audioStreamInfo: audio.AudioStreamInfo = {
142  samplingRate: audio.AudioSamplingRate.SAMPLE_RATE_48000, // 采样率
143  channels: audio.AudioChannel.CHANNEL_2, // 通道
144  sampleFormat: audio.AudioSampleFormat.SAMPLE_FORMAT_S16LE, // 采样格式
145  encodingType: audio.AudioEncodingType.ENCODING_TYPE_RAW // 编码格式
146};
147let audioCapturerInfo: audio.AudioCapturerInfo = {
148  source: audio.SourceType.SOURCE_TYPE_MIC, // 音源类型
149  capturerFlags: 0 // 音频采集器标志
150};
151let audioCapturerOptions: audio.AudioCapturerOptions = {
152  streamInfo: audioStreamInfo,
153  capturerInfo: audioCapturerInfo
154};
155let path = getContext().cacheDir;
156let filePath = path + '/StarWars10s-2C-48000-4SW.pcm';
157let file: fs.File = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
158let readDataCallback = (buffer: ArrayBuffer) => {
159   let options: Options = {
160      offset: bufferSize,
161      length: buffer.byteLength
162   }
163   fs.writeSync(file.fd, buffer, options);
164   bufferSize += buffer.byteLength;
165};
166
167// 初始化，创建实例，设置监听事件
168function init() {
169  audio.createAudioCapturer(audioCapturerOptions, (err, capturer) => { // 创建AudioCapturer实例
170    if (err) {
171      console.error(`Invoke createAudioCapturer failed, code is ${err.code}, message is ${err.message}`);
172      return;
173    }
174    console.info(`${TAG}: create AudioCapturer success`);
175    audioCapturer = capturer;
176    if (audioCapturer !== undefined) {
177       (audioCapturer as audio.AudioCapturer).on('readData', readDataCallback);
178    }
179  });
180}
181
182// 开始一次音频采集
183function start() {
184  if (audioCapturer !== undefined) {
185    let stateGroup = [audio.AudioState.STATE_PREPARED, audio.AudioState.STATE_PAUSED, audio.AudioState.STATE_STOPPED];
186    if (stateGroup.indexOf((audioCapturer as audio.AudioCapturer).state.valueOf()) === -1) { // 当且仅当状态为STATE_PREPARED、STATE_PAUSED和STATE_STOPPED之一时才能启动采集
187      console.error(`${TAG}: start failed`);
188      return;
189    }
190
191    // 启动采集
192    (audioCapturer as audio.AudioCapturer).start((err: BusinessError) => {
193      if (err) {
194        console.error('Capturer start failed.');
195      } else {
196        console.info('Capturer start success.');
197      }
198    });
199  }
200}
201
202// 停止采集
203function stop() {
204  if (audioCapturer !== undefined) {
205    // 只有采集器状态为STATE_RUNNING或STATE_PAUSED的时候才可以停止
206    if ((audioCapturer as audio.AudioCapturer).state.valueOf() !== audio.AudioState.STATE_RUNNING && (audioCapturer as audio.AudioCapturer).state.valueOf() !== audio.AudioState.STATE_PAUSED) {
207      console.info('Capturer is not running or paused');
208      return;
209    }
210
211    //停止采集
212    (audioCapturer as audio.AudioCapturer).stop((err: BusinessError) => {
213      if (err) {
214        console.error('Capturer stop failed.');
215      } else {
216        fs.close(file);
217        console.info('Capturer stop success.');
218      }
219    });
220  }
221}
222
223// 销毁实例，释放资源
224function release() {
225  if (audioCapturer !== undefined) {
226    // 采集器状态不是STATE_RELEASED或STATE_NEW状态，才能release
227    if ((audioCapturer as audio.AudioCapturer).state.valueOf() === audio.AudioState.STATE_RELEASED || (audioCapturer as audio.AudioCapturer).state.valueOf() === audio.AudioState.STATE_NEW) {
228      console.info('Capturer already released');
229      return;
230    }
231
232    //释放资源
233    (audioCapturer as audio.AudioCapturer).release((err: BusinessError) => {
234      if (err) {
235        console.error('Capturer release failed.');
236      } else {
237        console.info('Capturer release success.');
238      }
239    });
240  }
241}
242```
243