我正在尝试使用Playback Capture API在Android 10(Q)上录制音频。由于Playback Capture API仅允许使用USAGE_GAME、USAGE_MEDIA或USAGE_UNKNOWN记录声音，因此我已下载了Uamp示例，并在播放歌曲时设置了USAGE_MEDIA。我还在
我开发了一个名为CaptureAudio的项目，目标SDK为29，并将其安装在已安装Android 10的OnePlus 7 Pro上。UI上有两个按钮，用于开始和停止捕获。当应用程序开始捕获时，读取函数会将缓冲区中的所有0填充。
要在项目中使用回放捕获，我已经按照以下步骤设置：
The problem is, 1. 文件
AndroidManifest.xml中添加了android:allowAudioPlaybackCapture="true"。然后我启动了Uamp，开始播放歌曲并让其处于后台状态。我开发了一个名为CaptureAudio的项目，目标SDK为29，并将其安装在已安装Android 10的OnePlus 7 Pro上。UI上有两个按钮，用于开始和停止捕获。当应用程序开始捕获时，读取函数会将缓冲区中的所有0填充。
要在项目中使用回放捕获，我已经按照以下步骤设置：
1. 清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.captureaudio">
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAPTURE_AUDIO_OUTPUT" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:allowBackup="false"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme"
tools:ignore="GoogleAppIndexingWarning">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service
android:name=".services.MediaProjectionService"
android:enabled="true"
android:exported="false"
android:foregroundServiceType="mediaProjection"
tools:targetApi="q" />
</application>
</manifest>
2. MainActivity：
class MainActivity : AppCompatActivity() {
companion object {
private const val REQUEST_CODE_CAPTURE_INTENT = 1
private const val TAG = "CaptureAudio"
private const val RECORDER_SAMPLE_RATE = 48000
private const val RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO
//or AudioFormat.CHANNEL_IN_BACK
private const val RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT
// AudioFormat.ENCODING_PCM_16BIT
}
private var audioRecord: AudioRecord? = null
private val mediaProjectionManager by lazy { (this@MainActivity).getSystemService(Context.MEDIA_PROJECTION_SERVICE) as MediaProjectionManager }
private val rxPermissions by lazy { RxPermissions(this) }
private val minBufferSize by lazy {
AudioRecord.getMinBufferSize(
RECORDER_SAMPLE_RATE,
RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING
)
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val intent = Intent(this, MediaProjectionService::class.java)
startForegroundService(intent)
getPermissions()
}
private fun getPermissions() {
rxPermissions
.request(
Manifest.permission.RECORD_AUDIO,
Manifest.permission.FOREGROUND_SERVICE,
Manifest.permission.WRITE_EXTERNAL_STORAGE
)
.subscribe {
log("Permission result: $it")
if (it) { // Always true pre-M
val captureIntent = mediaProjectionManager.createScreenCaptureIntent()
startActivityForResult(captureIntent, REQUEST_CODE_CAPTURE_INTENT)
} else {
getPermissions()
}
}
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == REQUEST_CODE_CAPTURE_INTENT && data != null) {
val mediaProjection = mediaProjectionManager.getMediaProjection(resultCode, data)
val playbackConfig = AudioPlaybackCaptureConfiguration.Builder(mediaProjection)
.addMatchingUsage(AudioAttributes.USAGE_MEDIA)
.addMatchingUsage(AudioAttributes.USAGE_UNKNOWN)
.addMatchingUsage(AudioAttributes.USAGE_GAME)
.build()
audioRecord = AudioRecord.Builder()
.setAudioPlaybackCaptureConfig(playbackConfig)
.setBufferSizeInBytes(minBufferSize * 2)
.setAudioFormat(
AudioFormat.Builder()
.setEncoding(RECORDER_AUDIO_ENCODING)
.setSampleRate(RECORDER_SAMPLE_RATE)
.setChannelMask(RECORDER_CHANNELS)
.build()
)
.build()
}
}
fun startCapture(view: View) {
audioRecord?.apply {
startRecording()
log("Is stopped: $state $recordingState")
startRecordingIntoFile()
}
stopRecBtn.visibility = View.VISIBLE
startRecBtn.visibility = View.INVISIBLE
}
private fun AudioRecord.startRecordingIntoFile() {
val file = File(
getExternalFilesDir(Environment.DIRECTORY_MUSIC),
"temp.wav"
//System.currentTimeMillis().toString() + ".wav"
)
if (!file.exists())
file.createNewFile()
GlobalScope.launch {
val out = file.outputStream()
audioRecord.apply {
while (recordingState == AudioRecord.RECORDSTATE_RECORDING) {
val buffer = ShortArray(minBufferSize)//ByteBuffer.allocate(MIN_BUFFER_SIZE)
val result = read(buffer, 0, minBufferSize)
// Checking if I am actually getting something in a buffer
val b: Short = 0
var nonZeroValueCount = 0
for (i in 0 until minBufferSize) {
if (buffer[i] != b) {
nonZeroValueCount += 1
log("Value: ${buffer[i]}")
}
}
if (nonZeroValueCount != 0) {
// Record the non-zero values in the file..
log("Result $nonZeroValueCount")
when (result) {
AudioRecord.ERROR -> showToast("ERROR")
AudioRecord.ERROR_INVALID_OPERATION -> showToast("ERROR_INVALID_OPERATION")
AudioRecord.ERROR_DEAD_OBJECT -> showToast("ERROR_DEAD_OBJECT")
AudioRecord.ERROR_BAD_VALUE -> showToast("ERROR_BAD_VALUE")
else -> {
log("Appending $buffer into ${file.absolutePath}")
out.write(shortToByte(buffer))
}
}
}
}
}
out.close()
}
}
private fun shortToByte(shortArray: ShortArray): ByteArray {
val byteOut = ByteArray(shortArray.size * 2)
ByteBuffer.wrap(byteOut).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().put(shortArray)
return byteOut
}
private fun showToast(msg: String) {
runOnUiThread {
log("Toast: $msg")
Toast.makeText(this@MainActivity, msg, Toast.LENGTH_LONG).show()
}
}
fun stopCapture(view: View) {
audioRecord?.apply {
stop()
log("Is stopped: $state $recordingState")
}
stopRecBtn.visibility = View.INVISIBLE
startRecBtn.visibility = View.VISIBLE
}
private fun log(msg: String) {
Log.d(TAG, msg)
}
override fun onDestroy() {
super.onDestroy()
audioRecord?.stop()
audioRecord?.release()
audioRecord = null
}
}
3. 媒体投影服务
class MediaProjectionService : Service() {
companion object {
private const val CHANNEL_ID = "ForegroundServiceChannel"
}
override fun onBind(intent: Intent?): IBinder? {
return null
}
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
createNotificationChannel()
val notificationIntent = Intent(this, MainActivity::class.java)
val pendingIntent = PendingIntent.getActivity(
this,
0, notificationIntent, 0
)
val notification = NotificationCompat.Builder(this, CHANNEL_ID)
.setContentTitle("Foreground Service")
.setContentText("Call Recording Service")
// .setSmallIcon(R.drawable.ic_stat_name)
.setContentIntent(pendingIntent)
.build()
startForeground(1, notification)
return START_NOT_STICKY
}
private fun createNotificationChannel() {
val serviceChannel = NotificationChannel(
CHANNEL_ID,
"Foreground Service Channel",
NotificationManager.IMPORTANCE_DEFAULT
)
val manager = getSystemService(NotificationManager::class.java)
manager!!.createNotificationChannel(serviceChannel)
}
}
The problem is, 1. 文件
/storage/emulated/0/Android/data/com.example.captureaudio/files/Music/temp.wav 已创建，但其中只有 0 秒的内容。我也使用以下命令检查了文件：xxd /storage/emulated/0/Android/data/com.example.captureaudio/files/Music/temp.wav。OnePlus7Pro:/sdcard # xxd /storage/emulated/0/Android/data/com.example.captureaudio/files/Music/temp.wav | head
00000000: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000010: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000020: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000030: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000040: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000050: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000060: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000070: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000080: 0000 0000 0000 0000 0000 0000 0000 0000 ................
00000090: 0000 0000 0000 0000 0000 0000 0000 0000 ................
2. 在设备上播放时，出现错误“无法播放请求的音轨”。
有什么帮助或建议，我错过了什么吗？