ExtAudioRecorder：“写入失败：EBADF（错误文件描述符）”将音频录制到 WAV 文件 - Android Studio
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【中文标题】ExtAudioRecorder：“写入失败：EBADF（错误文件描述符）”将音频录制到 WAV 文件 - Android Studio【英文标题】：ExtAudioRecorder: "write failed: EBADF (Bad file descriptor) " in recording Audio to WAV files - Android Studio 【发布时间】：2021-09-06 12:56:27 【问题描述】：我正在尝试创建一个从麦克风录制并将文件保存为 WAV 格式的应用程序。 我发现这个 java 类可以帮助我以 WAV 格式录制和保存我的录音。
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.media.MediaRecorder.Audiosource;
import android.util.Log;
public class ExtAudioRecorder
private final static int[] sampleRates = 44100, 22050, 11025, 8000;
public static ExtAudioRecorder getInstanse(Boolean recordingCompressed)
ExtAudioRecorder result = null;
if(recordingCompressed)
result = new ExtAudioRecorder( false,
AudioSource.MIC,
sampleRates[3],
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT);
else
int i=0;
do
result = new ExtAudioRecorder( true,
AudioSource.MIC,
sampleRates[i],
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT);
while((++i<sampleRates.length) & !(result.getState() == ExtAudioRecorder.State.INITIALIZING));
return result;
/**
* INITIALIZING : recorder is initializing;
* READY : recorder has been initialized, recorder not yet started
* RECORDING : recording
* ERROR : reconstruction needed
* STOPPED: reset needed
*/
public enum State INITIALIZING, READY, RECORDING, ERROR, STOPPED;
public static final boolean RECORDING_UNCOMPRESSED = true;
public static final boolean RECORDING_COMPRESSED = false;
// The interval in which the recorded samples are output to the file
// Used only in uncompressed mode
private static final int TIMER_INTERVAL = 120;
// Toggles uncompressed recording on/off; RECORDING_UNCOMPRESSED / RECORDING_COMPRESSED
private boolean rUncompressed;
// Recorder used for uncompressed recording
private AudioRecord audioRecorder = null;
// Recorder used for compressed recording
private MediaRecorder mediaRecorder = null;
// Stores current amplitude (only in uncompressed mode)
private int cAmplitude= 0;
// Output file path
private String filePath = null;
// Recorder state; see State
private State state;
// File writer (only in uncompressed mode)
private RandomAccessFile randomAccessWriter;
// Number of channels, sample rate, sample size(size in bits), buffer size, audio source, sample size(see AudioFormat)
private short nChannels;
private int sRate;
private short bSamples;
private int bufferSize;
private int aSource;
private int aFormat;
// Number of frames written to file on each output(only in uncompressed mode)
private int framePeriod;
// Buffer for output(only in uncompressed mode)
private byte[] buffer;
// Number of bytes written to file after header(only in uncompressed mode)
// after stop() is called, this size is written to the header/data chunk in the wave file
private int payloadSize;
/**
*
* Returns the state of the recorder in a RehearsalAudioRecord.State typed object.
* Useful, as no exceptions are thrown.
*
* @return recorder state
*/
public State getState()
return state;
/*
*
* Method used for recording.
*
*/
private AudioRecord.OnRecordPositionUpdateListener updateListener = new AudioRecord.OnRecordPositionUpdateListener()
public void onPeriodicNotification(AudioRecord recorder)
audioRecorder.read(buffer, 0, buffer.length); // Fill buffer
try
randomAccessWriter.write(buffer); // Write buffer to file
payloadSize += buffer.length;
if (bSamples == 16)
for (int i=0; i<buffer.length/2; i++)
// 16bit sample size
short curSample = getShort(buffer[i*2], buffer[i*2+1]);
if (curSample > cAmplitude)
// Check amplitude
cAmplitude = curSample;
else
// 8bit sample size
for (int i=0; i<buffer.length; i++)
if (buffer[i] > cAmplitude)
// Check amplitude
cAmplitude = buffer[i];
catch (IOException e)
Log.e(ExtAudioRecorder.class.getName(), "Error occured in updateListener, recording is aborted");
//stop();
public void onMarkerReached(AudioRecord recorder)
// NOT USED
;
/**
*
*
* Default constructor
*
* Instantiates a new recorder, in case of compressed recording the parameters can be left as 0.
* In case of errors, no exception is thrown, but the state is set to ERROR
*
*/
public ExtAudioRecorder(boolean uncompressed, int audioSource, int sampleRate, int channelConfig, int audioFormat)
try
rUncompressed = uncompressed;
if (rUncompressed)
// RECORDING_UNCOMPRESSED
Log.e(ExtAudioRecorder.class.getName(), "uncompressed recording");
if (audioFormat == AudioFormat.ENCODING_PCM_16BIT)
bSamples = 16;
else
bSamples = 8;
if (channelConfig == AudioFormat.CHANNEL_CONFIGURATION_MONO)
nChannels = 1;
else
nChannels = 2;
aSource = audioSource;
sRate = sampleRate;
aFormat = audioFormat;
framePeriod = sampleRate * TIMER_INTERVAL / 1000;
bufferSize = framePeriod * 2 * bSamples * nChannels / 8;
if (bufferSize < AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat))
// Check to make sure buffer size is not smaller than the smallest allowed one
bufferSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
// Set frame period and timer interval accordingly
framePeriod = bufferSize / ( 2 * bSamples * nChannels / 8 );
Log.w(ExtAudioRecorder.class.getName(), "Increasing buffer size to " + Integer.toString(bufferSize));
audioRecorder = new AudioRecord(audioSource, sampleRate, channelConfig, audioFormat, bufferSize);
if (audioRecorder.getState() != AudioRecord.STATE_INITIALIZED)
throw new Exception("AudioRecord initialization failed");
audioRecorder.setRecordPositionUpdateListener(updateListener);
audioRecorder.setPositionNotificationPeriod(framePeriod);
else
// RECORDING_COMPRESSED
Log.e(ExtAudioRecorder.class.getName(), "compressed recording");
mediaRecorder = new MediaRecorder();
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
cAmplitude = 0;
filePath = null;
state = State.INITIALIZING;
catch (Exception e)
if (e.getMessage() != null)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
else
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
state = State.ERROR;
/**
* Sets output file path, call directly after construction/reset.
*
* # @param output file path
*
*/
public void setOutputFile(String argPath)
try
if (state == State.INITIALIZING)
filePath = argPath;
if (!rUncompressed)
mediaRecorder.setOutputFile(filePath);
catch (Exception e)
if (e.getMessage() != null)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
else
Log.e(ExtAudioRecorder.class.getName(), "Unknown error occured while setting output path");
state = State.ERROR;
/**
*
* Returns the largest amplitude sampled since the last call to this method.
*
* @return returns the largest amplitude since the last call, or 0 when not in recording state.
*
*/
public int getMaxAmplitude()
if (state == State.RECORDING)
if (rUncompressed)
int result = cAmplitude;
cAmplitude = 0;
return result;
else
try
return mediaRecorder.getMaxAmplitude();
catch (IllegalStateException e)
return 0;
else
return 0;
/**
*
* Prepares the recorder for recording, in case the recorder is not in the INITIALIZING state and the file path was not set
* the recorder is set to the ERROR state, which makes a reconstruction necessary.
* In case uncompressed recording is toggled, the header of the wave file is written.
* In case of an exception, the state is changed to ERROR
*
*/
public void prepare()
try
if (state == State.INITIALIZING)
if (rUncompressed)
if ((audioRecorder.getState() == AudioRecord.STATE_INITIALIZED) & (filePath != null))
// write file header
randomAccessWriter = new RandomAccessFile(filePath, "rw");
randomAccessWriter.setLength(0); // Set file length to 0, to prevent unexpected behavior in case the file already existed
randomAccessWriter.writeBytes("RIFF");
randomAccessWriter.writeInt(0); // Final file size not known yet, write 0
randomAccessWriter.writeBytes("WAVE");
randomAccessWriter.writeBytes("fmt ");
randomAccessWriter.writeInt(Integer.reverseBytes(16)); // Sub-chunk size, 16 for PCM
randomAccessWriter.writeShort(Short.reverseBytes((short) 1)); // AudioFormat, 1 for PCM
randomAccessWriter.writeShort(Short.reverseBytes(nChannels));// Number of channels, 1 for mono, 2 for stereo
randomAccessWriter.writeInt(Integer.reverseBytes(sRate)); // Sample rate
randomAccessWriter.writeInt(Integer.reverseBytes(sRate*bSamples*nChannels/8)); // Byte rate, SampleRate*NumberOfChannels*BitsPerSample/8
randomAccessWriter.writeShort(Short.reverseBytes((short)(nChannels*bSamples/8))); // Block align, NumberOfChannels*BitsPerSample/8
randomAccessWriter.writeShort(Short.reverseBytes(bSamples)); // Bits per sample
randomAccessWriter.writeBytes("data");
randomAccessWriter.writeInt(0); // Data chunk size not known yet, write 0
buffer = new byte[framePeriod*bSamples/8*nChannels];
state = State.READY;
else
Log.e(ExtAudioRecorder.class.getName(), "prepare() method called on uninitialized recorder");
state = State.ERROR;
else
mediaRecorder.prepare();
state = State.READY;
else
Log.e(ExtAudioRecorder.class.getName(), "prepare() method called on illegal state");
release();
state = State.ERROR;
catch(Exception e)
if (e.getMessage() != null)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
else
Log.e(ExtAudioRecorder.class.getName(), "Unknown error occured in prepare()");
state = State.ERROR;
/**
*
*
* Releases the resources associated with this class, and removes the unnecessary files, when necessary
*
*/
public void release()
if (state == State.RECORDING)
stop();
else
if ((state == State.READY) & (rUncompressed))
try
randomAccessWriter.close(); // Remove prepared file
catch (IOException e)
Log.e(ExtAudioRecorder.class.getName(), "I/O exception occured while closing output file");
(new File(filePath)).delete();
if (rUncompressed)
if (audioRecorder != null)
audioRecorder.release();
else
if (mediaRecorder != null)
mediaRecorder.release();
/**
*
*
* Resets the recorder to the INITIALIZING state, as if it was just created.
* In case the class was in RECORDING state, the recording is stopped.
* In case of exceptions the class is set to the ERROR state.
*
*/
public void reset()
try
if (state != State.ERROR)
release();
filePath = null; // Reset file path
cAmplitude = 0; // Reset amplitude
if (rUncompressed)
audioRecorder = new AudioRecord(aSource, sRate, nChannels+1, aFormat, bufferSize);
else
mediaRecorder = new MediaRecorder();
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
state = State.INITIALIZING;
catch (Exception e)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
state = State.ERROR;
/**
*
*
* Starts the recording, and sets the state to RECORDING.
* Call after prepare().
*
*/
public void start()
if (state == State.READY)
if (rUncompressed)
payloadSize = 0;
audioRecorder.startRecording();
audioRecorder.read(buffer, 0, buffer.length);
else
mediaRecorder.start();
state = State.RECORDING;
else
Log.e(ExtAudioRecorder.class.getName(), "start() called on illegal state");
state = State.ERROR;
/**
*
*
* Stops the recording, and sets the state to STOPPED.
* In case of further usage, a reset is needed.
* Also finalizes the wave file in case of uncompressed recording.
*
*/
public void stop()
if (state == State.RECORDING)
if (rUncompressed)
audioRecorder.stop();
try
randomAccessWriter.seek(4); // Write size to RIFF header
randomAccessWriter.writeInt(Integer.reverseBytes(36+payloadSize));
randomAccessWriter.seek(40); // Write size to Subchunk2Size field
randomAccessWriter.writeInt(Integer.reverseBytes(payloadSize));
randomAccessWriter.close();
catch(IOException e)
Log.e(ExtAudioRecorder.class.getName(), "I/O exception occured while closing output file");
state = State.ERROR;
else
mediaRecorder.stop();
state = State.STOPPED;
else
Log.e(ExtAudioRecorder.class.getName(), "stop() called on illegal state");
state = State.ERROR;
/*
*
* Converts a byte[2] to a short, in LITTLE_ENDIAN format
*
*/
private short getShort(byte argB1, byte argB2)
return (short)(argB1 | (argB2 << 8));
我的主要活动是：
import static android.Manifest.permission.RECORD_AUDIO;
import static android.Manifest.permission.WRITE_EXTERNAL_STORAGE;
public class MainActivity extends AppCompatActivity
Button buttonStart, buttonStop, buttonPlayLastRecordAudio,
buttonStopPlayingRecording, buttonGet;
String AudioSavePathInDevice = null;
MediaRecorder mediaRecorder ;
Random random ;
View loader;
AudioRecordView audioRecordView;
String RandomAudioFileName = "ABCDEFGHIJKLMNOPQ";
public static final int RequestPermissionCode = 1;
MediaPlayer mediaPlayer ;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonStart = (Button) findViewById(R.id.button_record);
buttonStop = (Button) findViewById(R.id.button_stop_record);
buttonPlayLastRecordAudio = (Button) findViewById(R.id.button_play);
buttonStopPlayingRecording = (Button)findViewById(R.id.button_stop_play);
loader = findViewById(R.id.loader);
ExtAudioRecorder extAudioRecorder = ExtAudioRecorder.getInstanse(false);
random = new Random();
buttonStart.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
if(checkPermission())
AudioSavePathInDevice =
Environment.getExternalStorageDirectory().getAbsolutePath() + "/" +
CreateRandomAudioFileName(5) + "AudioRecording.WAV";
extAudioRecorder.setOutputFile(AudioSavePathInDevice);
try
extAudioRecorder.prepare();
extAudioRecorder.start();
catch (IllegalStateException e)
// TODO Auto-generated catch block
e.printStackTrace();
else
requestPermission();
);
buttonStop.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
extAudioRecorder.stop();
extAudioRecorder.release();
Toast.makeText(MainActivity.this, "Recording Completed",
Toast.LENGTH_LONG).show();
);
buttonPlayLastRecordAudio.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view) throws IllegalArgumentException,
SecurityException, IllegalStateException
mediaPlayer = new MediaPlayer();
try
mediaPlayer.setDataSource(AudioSavePathInDevice);
mediaPlayer.prepare();
catch (IOException e)
e.printStackTrace();
mediaPlayer.start();
Toast.makeText(MainActivity.this, "Recording Playing",
Toast.LENGTH_LONG).show();
);
buttonStopPlayingRecording.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
if(mediaPlayer != null)
mediaPlayer.stop();
mediaPlayer.release();
MediaRecorderReady();
);
public void MediaRecorderReady()
mediaRecorder = new MediaRecorder();
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
mediaRecorder.setOutputFile(AudioSavePathInDevice);
public String CreateRandomAudioFileName(int string)
StringBuilder stringBuilder = new StringBuilder( string );
int i = 0 ;
while(i < string )
stringBuilder.append(RandomAudioFileName.
charAt(random.nextInt(RandomAudioFileName.length())));
i++ ;
return stringBuilder.toString();
private void requestPermission()
ActivityCompat.requestPermissions(MainActivity.this, new
String[]WRITE_EXTERNAL_STORAGE, RECORD_AUDIO, RequestPermissionCode);
@Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults)
switch (requestCode)
case RequestPermissionCode:
if (grantResults.length> 0)
boolean StoragePermission = grantResults[0] ==
PackageManager.PERMISSION_GRANTED;
boolean RecordPermission = grantResults[1] ==
PackageManager.PERMISSION_GRANTED;
if (StoragePermission && RecordPermission)
Toast.makeText(MainActivity.this, "Permission Granted",
Toast.LENGTH_LONG).show();
else
Toast.makeText(MainActivity.this,"Permission Denied",Toast.LENGTH_LONG).show();
break;
public boolean checkPermission()
int result = ContextCompat.checkSelfPermission(getApplicationContext(),
WRITE_EXTERNAL_STORAGE);
int result1 = ContextCompat.checkSelfPermission(getApplicationContext(),
RECORD_AUDIO);
return result == PackageManager.PERMISSION_GRANTED &&
result1 == PackageManager.PERMISSION_GRANTED;
public static String getMimeType(String url)
String type = null;
String extension = MimeTypeMap.getFileExtensionFromUrl(url);
if (extension != null)
type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
return type;
我可以录制我的第一个录音并使用媒体录音机播放，但我似乎无法录制第二个录音也无法播放。
在我停止第一次录制后，我收到此错误：
E/com.example.app.ExtAudioRecorder: write failed: EBADF (Bad file descriptor)
我已经添加了所有必需的权限，但我真的被这个权限卡住了。
有什么想法吗？
【问题讨论】：
【参考方案1】：事实证明，如果其他人遇到同样的问题，我找到了解决问题的方法。我实际上修改了 ExtAudioRecorder 类，现在一切似乎都正常了。
尤其是在改变这一行之后：
audioRecorder = new AudioRecord(aSource, sRate, nChannels + 1, aFormat, bufferSize);
进入这个：
audioRecorder = new AudioRecord(aSource, sRate, nChannels, aFormat, bufferSize);
我认为问题出在某个地方。
ExtAudioRecorder.java 文件的修改代码如下：
public class ExtAudioRecorder
private final static int[] sampleRates = 44100, 22050, 11025, 8000;
public static ExtAudioRecorder getInstanse(Boolean recordingCompressed)
ExtAudioRecorder result = null;
if(recordingCompressed)
result = new ExtAudioRecorder( false,
AudioSource.MIC,
sampleRates[3],
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT);
else
int i=0;
do
result = new ExtAudioRecorder( true,
AudioSource.MIC,
sampleRates[i],
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT);
while((++i<sampleRates.length) & !(result.getState() == ExtAudioRecorder.State.INITIALIZING));
return result;
/**
* INITIALIZING : recorder is initializing;
* READY : recorder has been initialized, recorder not yet started
* RECORDING : recording
* ERROR : reconstruction needed
* STOPPED: reset needed
*/
public enum State INITIALIZING, READY, RECORDING, ERROR, STOPPED;
public static final boolean RECORDING_UNCOMPRESSED = true;
public static final boolean RECORDING_COMPRESSED = false;
// The interval in which the recorded samples are output to the file
// Used only in uncompressed mode
private static final int TIMER_INTERVAL = 120;
// Toggles uncompressed recording on/off; RECORDING_UNCOMPRESSED / RECORDING_COMPRESSED
private boolean rUncompressed;
// Recorder used for uncompressed recording
private AudioRecord audioRecorder = null;
// Recorder used for compressed recording
private MediaRecorder mediaRecorder = null;
// Stores current amplitude (only in uncompressed mode)
private int cAmplitude= 0;
// Output file path
private String filePath = null;
// Recorder state; see State
private State state;
// File writer (only in uncompressed mode)
private RandomAccessFile randomAccessWriter;
// Number of channels, sample rate, sample size(size in bits), buffer size, audio source, sample size(see AudioFormat)
private short nChannels;
private int sRate;
private short bSamples;
private int bufferSize;
private int aSource;
private int aFormat;
// Number of frames written to file on each output(only in uncompressed mode)
private int framePeriod;
// Buffer for output(only in uncompressed mode)
private byte[] buffer;
// Number of bytes written to file after header(only in uncompressed mode)
// after stop() is called, this size is written to the header/data chunk in the wave file
private int payloadSize;
/**
*
* Returns the state of the recorder in a RehearsalAudioRecord.State typed object.
* Useful, as no exceptions are thrown.
*
* @return recorder state
*/
public State getState()
return state;
/*
*
* Method used for recording.
*
*/
private AudioRecord.OnRecordPositionUpdateListener updateListener = new AudioRecord.OnRecordPositionUpdateListener()
public void onPeriodicNotification(AudioRecord recorder)
if (State.STOPPED == state)
Log.d(ExtAudioRecorder.this.getClass().getName(), "recorder stopped");
return;
audioRecorder.read(buffer, 0, buffer.length); // Fill buffer
try
randomAccessWriter.write(buffer); // Write buffer to file
payloadSize += buffer.length;
if (bSamples == 16)
for (int i=0; i<buffer.length/2; i++)
// 16bit sample size
short curSample = getShort(buffer[i*2], buffer[i*2+1]);
if (curSample > cAmplitude)
// Check amplitude
cAmplitude = curSample;
else
// 8bit sample size
for (int i=0; i<buffer.length; i++)
if (buffer[i] > cAmplitude)
// Check amplitude
cAmplitude = buffer[i];
catch (IOException e)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
public void onMarkerReached(AudioRecord recorder)
;
/**
*
*
* Default constructor
*
* Instantiates a new recorder, in case of compressed recording the parameters can be left as 0.
* In case of errors, no exception is thrown, but the state is set to ERROR
*
*/
public ExtAudioRecorder(boolean uncompressed, int audioSource, int sampleRate, int channelConfig, int audioFormat)
try
rUncompressed = uncompressed;
if (rUncompressed)
// RECORDING_UNCOMPRESSED
Log.d(ExtAudioRecorder.class.getName(), "uncompressed recording");
if (audioFormat == AudioFormat.ENCODING_PCM_16BIT)
bSamples = 16;
else
bSamples = 8;
if (channelConfig == AudioFormat.CHANNEL_CONFIGURATION_MONO)
nChannels = 1;
else
nChannels = 2;
aSource = audioSource;
sRate = sampleRate;
aFormat = audioFormat;
framePeriod = sampleRate * TIMER_INTERVAL / 1000;
bufferSize = framePeriod * 2 * bSamples * nChannels / 8;
if (bufferSize < AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat))
// Check to make sure buffer size is not smaller than the smallest allowed one
bufferSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
// Set frame period and timer interval accordingly
framePeriod = bufferSize / ( 2 * bSamples * nChannels / 8 );
Log.w(ExtAudioRecorder.class.getName(), "Increasing buffer size to " + Integer.toString(bufferSize));
audioRecorder = new AudioRecord(audioSource, sampleRate, channelConfig, audioFormat, bufferSize);
if (audioRecorder.getState() != AudioRecord.STATE_INITIALIZED)
throw new Exception("AudioRecord initialization failed");
audioRecorder.setRecordPositionUpdateListener(updateListener);
audioRecorder.setPositionNotificationPeriod(framePeriod);
else
// RECORDING_COMPRESSED
Log.e(ExtAudioRecorder.class.getName(), "compressed recording");
mediaRecorder = new MediaRecorder();
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
cAmplitude = 0;
filePath = null;
state = State.INITIALIZING;
catch (Exception e)
if (e.getMessage() != null)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
else
Log.e(ExtAudioRecorder.class.getName(), "Unknown error occured while initializing recording");
state = State.ERROR;
/**
* Sets output file path, call directly after construction/reset.
*
* # @param output file path
*
*/
public void setOutputFile(String argPath)
try
if (state == State.INITIALIZING)
filePath = argPath;
if (!rUncompressed)
mediaRecorder.setOutputFile(filePath);
catch (Exception e)
if (e.getMessage() != null)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
else
Log.e(ExtAudioRecorder.class.getName(), "Unknown error occured while setting output path");
state = State.ERROR;
/**
*
* Returns the largest amplitude sampled since the last call to this method.
*
* @return returns the largest amplitude since the last call, or 0 when not in recording state.
*
*/
public int getMaxAmplitude()
if (state == State.RECORDING)
if (rUncompressed)
int result = cAmplitude;
cAmplitude = 0;
return result;
else
try
return mediaRecorder.getMaxAmplitude();
catch (IllegalStateException e)
return 0;
else
return 0;
/**
*
* Prepares the recorder for recording, in case the recorder is not in the INITIALIZING state and the file path was not set
* the recorder is set to the ERROR state, which makes a reconstruction necessary.
* In case uncompressed recording is toggled, the header of the wave file is written.
* In case of an exception, the state is changed to ERROR
*
*/
public void prepare()
try
if (state == State.INITIALIZING)
if (rUncompressed)
if ((audioRecorder.getState() == AudioRecord.STATE_INITIALIZED) & (filePath != null))
// write file header
randomAccessWriter = new RandomAccessFile(filePath, "rw");
randomAccessWriter.setLength(0); // Set file length to 0, to prevent unexpected behavior in case the file already existed
randomAccessWriter.writeBytes("RIFF");
randomAccessWriter.writeInt(0); // Final file size not known yet, write 0
randomAccessWriter.writeBytes("WAVE");
randomAccessWriter.writeBytes("fmt ");
randomAccessWriter.writeInt(Integer.reverseBytes(16)); // Sub-chunk size, 16 for PCM
randomAccessWriter.writeShort(Short.reverseBytes((short) 1)); // AudioFormat, 1 for PCM
randomAccessWriter.writeShort(Short.reverseBytes(nChannels));// Number of channels, 1 for mono, 2 for stereo
randomAccessWriter.writeInt(Integer.reverseBytes(sRate)); // Sample rate
randomAccessWriter.writeInt(Integer.reverseBytes(sRate*bSamples*nChannels/8)); // Byte rate, SampleRate*NumberOfChannels*BitsPerSample/8
randomAccessWriter.writeShort(Short.reverseBytes((short)(nChannels*bSamples/8))); // Block align, NumberOfChannels*BitsPerSample/8
randomAccessWriter.writeShort(Short.reverseBytes(bSamples)); // Bits per sample
randomAccessWriter.writeBytes("data");
randomAccessWriter.writeInt(0); // Data chunk size not known yet, write 0
buffer = new byte[framePeriod*bSamples/8*nChannels];
state = State.READY;
else
Log.e(ExtAudioRecorder.class.getName(), "prepare() method called on uninitialized recorder");
state = State.ERROR;
else
mediaRecorder.prepare();
state = State.READY;
else
Log.e(ExtAudioRecorder.class.getName(), "prepare() method called on illegal state");
release();
state = State.ERROR;
catch(Exception e)
if (e.getMessage() != null)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
else
Log.e(ExtAudioRecorder.class.getName(), "Unknown error occured in prepare()");
state = State.ERROR;
/**
*
*
* Releases the resources associated with this class, and removes the unnecessary files, when necessary
*
*/
public void release()
if (state == State.RECORDING)
stop();
else
if ((state == State.READY) & (rUncompressed))
try
randomAccessWriter.close(); // Remove prepared file
catch (IOException e)
Log.e(ExtAudioRecorder.class.getName(), "I/O exception occured while closing output file");
(new File(filePath)).delete();
if (rUncompressed)
if (audioRecorder != null)
audioRecorder.release();
else
if (mediaRecorder != null)
mediaRecorder.release();
/**
*
*
* Resets the recorder to the INITIALIZING state, as if it was just created.
* In case the class was in RECORDING state, the recording is stopped.
* In case of exceptions the class is set to the ERROR state.
*
*/
public void reset()
try
if (state != State.ERROR)
release();
filePath = null; // Reset file path
cAmplitude = 0; // Reset amplitude
if (rUncompressed)
audioRecorder = new AudioRecord(aSource, sRate, nChannels, aFormat, bufferSize);
audioRecorder.setRecordPositionUpdateListener(updateListener);
audioRecorder.setPositionNotificationPeriod(framePeriod);
else
mediaRecorder = new MediaRecorder();
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
state = State.INITIALIZING;
catch (Exception e)
Log.e(ExtAudioRecorder.class.getName(), e.getMessage());
state = State.ERROR;
/**
*
*
* Starts the recording, and sets the state to RECORDING.
* Call after prepare().
*
*/
public void start()
if (state == State.READY)
if (rUncompressed)
payloadSize = 0;
audioRecorder.startRecording();
audioRecorder.read(buffer, 0, buffer.length);
else
mediaRecorder.start();
state = State.RECORDING;
else
Log.e(ExtAudioRecorder.class.getName(), "start() called on illegal state");
state = State.ERROR;
/**
*
*
* Stops the recording, and sets the state to STOPPED.
* In case of further usage, a reset is needed.
* Also finalizes the wave file in case of uncompressed recording.
*
*/
public void stop()
if (state == State.RECORDING)
if (rUncompressed)
audioRecorder.stop();
try
randomAccessWriter.seek(4); // Write size to RIFF header
randomAccessWriter.writeInt(Integer.reverseBytes(36+payloadSize));
randomAccessWriter.seek(40); // Write size to Subchunk2Size field
randomAccessWriter.writeInt(Integer.reverseBytes(payloadSize));
randomAccessWriter.close();
catch(IOException e)
Log.e(ExtAudioRecorder.class.getName(), "I/O exception occured while closing output file");
state = State.ERROR;
else
mediaRecorder.stop();
state = State.STOPPED;
else
Log.e(ExtAudioRecorder.class.getName(), "stop() called on illegal state");
state = State.ERROR;
/*
*
* Converts a byte[2] to a short, in LITTLE_ENDIAN format
*
*/
private short getShort(byte argB1, byte argB2)
return (short)(argB1 | (argB2 << 8));
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