问题
I'm developing an Android application, which supports audio recording with the following code, sample can be found here:
http://developer.samsung.com/technical-doc/view.do;jsessionid=tT01JrgM5DRC15pN56v20xzJXcDYv7hZVLvPhT0zJ4kfvSc1TlTM!-846162528?v=T000000090
Variables:
private static final int RECORDER_BPP = 16;
private static final int RECORDER_SAMPLERATE = 22050;
private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
private static final int RECORDER_CHANNELS_NUMBER = 1;
private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
private AudioRecord recorder = null;
private short[] mBuffer;
private int bufferSize = 0;
private boolean IsRecording = false;
Assign a value to bufferSize:
bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT);
Create the recorder:
recorder = new AudioRecord(source, RECORDER_SAMPLERATE, RECORDER_CHANNELS,RECORDER_AUDIO_ENCODING, bufferSize);
The source indicates the microphone to use.
Storing the received content in the raw file:
new Thread(new Runnable() {
@Override
public void run() {
DataOutputStream output = null;
try {
output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(new File(getTempFilename()))));
while (IsRecording) {
int readSize = recorder.read(mBuffer, 0, mBuffer.length);
for (int i = 0; i < readSize; i++) {
output.writeShort(mBuffer[i]);
}
}
} catch (IOException e) {
Toast.makeText(mContext, e.getMessage(), Toast.LENGTH_SHORT).show();
} finally {
if (output != null) {
try {
output.flush();
} catch (IOException e) {
Toast.makeText(mContext, e.getMessage(), Toast.LENGTH_SHORT).show();
} finally {
try {
output.close();
} catch (IOException e) {
Toast.makeText(mContext, e.getMessage(), Toast.LENGTH_SHORT).show();
}
}
}
}
}
}).start();
I would like to:
- Play the recorded audio with android.media.MediaPlayer
- On another activity, encode the raw source to mp3.
According to the above page I could compile the Lame library and create the wrapper. So, this raw file can be encoded to mp3 without any problems, but I can not find a way how to make this raw source playable before encoding. The found solutions for create wave header for the raw are unusable.
Has anybody have a solution for this?
Update: For creating the headers I tried this: ...
in = new FileInputStream(inFilename);
totalAudioLen = in.getChannel().size();
totalDataLen = totalAudioLen + 36;
long longSampleRate = RECORDER_SAMPLERATE;
int channels = 1;
long byteRate = RECORDER_BPP * RECORDER_SAMPLERATE * channels/8;
...
WriteWaveFileHeader(out, totalAudioLen, totalDataLen,
longSampleRate, channels, byteRate);
private void WriteWaveFileHeader(
FileOutputStream out, long totalAudioLen,
long totalDataLen, long longSampleRate, int channels,
long byteRate) throws IOException {
byte[] header = new byte[44];
header[0] = 'R'; // RIFF/WAVE header
header[1] = 'I';
header[2] = 'F';
header[3] = 'F';
header[4] = (byte) (totalDataLen & 0xff);
header[5] = (byte) ((totalDataLen >> 8) & 0xff);
header[6] = (byte) ((totalDataLen >> 16) & 0xff);
header[7] = (byte) ((totalDataLen >> 24) & 0xff);
header[8] = 'W';
header[9] = 'A';
header[10] = 'V';
header[11] = 'E';
header[12] = 'f'; // 'fmt ' chunk
header[13] = 'm';
header[14] = 't';
header[15] = ' ';
header[16] = 16; // 4 bytes: size of 'fmt ' chunk
header[17] = 0;
header[18] = 0;
header[19] = 0;
header[20] = 1; // format = 1
header[21] = 0;
header[22] = (byte) channels;
header[23] = 0;
header[24] = (byte) (longSampleRate & 0xff);
header[25] = (byte) ((longSampleRate >> 8) & 0xff);
header[26] = (byte) ((longSampleRate >> 16) & 0xff);
header[27] = (byte) ((longSampleRate >> 24) & 0xff);
header[28] = (byte) (byteRate & 0xff);
header[29] = (byte) ((byteRate >> 8) & 0xff);
header[30] = (byte) ((byteRate >> 16) & 0xff);
header[31] = (byte) ((byteRate >> 24) & 0xff);
header[32] = (byte) (2 * 16 / 8); // block align
header[33] = 0;
header[34] = RECORDER_BPP; // bits per sample
header[35] = 0;
header[36] = 'd';
header[37] = 'a';
header[38] = 't';
header[39] = 'a';
header[40] = (byte) (totalAudioLen & 0xff);
header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
out.write(header, 0, 44);
}
The result is a noisy wave file
Thank you
回答1:
If you are getting a noisy WAV, the reason could be a problem with the endian-ness of your 16-bit samples. Try swizzling the bytes around when you write them, like this:
int readSize = recorder.read(mBuffer, 0, mBuffer.length);
for (int i = 0; i < readSize; i++) {
output.writeShort(((mBuffer[i] >> 8) & 255) | (mBuffer[i] << 8));
}
回答2:
Here, this is my code, which work for me (record raw pcm audio and save it, play it afterwards with audiotrack):
public class MainActivity extends Activity
{
AudioRecord record = null;
AudioTrack track = null;
boolean isRecording;
int sampleRate = 44100;
Button startRecord, stopRecord, playRecord = null;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setVolumeControlStream(AudioManager.MODE_IN_COMMUNICATION);
startRecord = (Button) findViewById(R.id.start_recording);
stopRecord = (Button) findViewById(R.id.stop_recording);
playRecord = (Button) findViewById(R.id.play_recording);
startRecord.setOnClickListener(new StartRecordListener());
stopRecord.setOnClickListener(new StopRecordListener());
playRecord.setOnClickListener(new PlayRecordListener());
stopRecord.setEnabled(false);
}
private void startRecord()
{
File recordFile = new File(Environment.getExternalStorageDirectory(), "Record.pcm");
try
{
recordFile.createNewFile();
OutputStream outputStream = new FileOutputStream(recordFile);
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outputStream);
DataOutputStream dataOutputStream = new DataOutputStream(bufferedOutputStream);
int minBufferSize = AudioRecord.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
short[] audioData = new short[minBufferSize];
record = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT,
minBufferSize);
record.startRecording();
while (isRecording)
{
int numberOfShort = record.read(audioData, 0, minBufferSize);
for (int i = 0; i < numberOfShort; i++)
{
dataOutputStream.writeShort(audioData[i]);
}
}
record.stop();
dataOutputStream.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
public void playRecord()
{
File recordFile = new File(Environment.getExternalStorageDirectory(), "Record.pcm");
int shortSizeInBytes = Short.SIZE / Byte.SIZE;
int bufferSizeInBytes = (int) (recordFile.length() / shortSizeInBytes);
short[] audioData = new short[bufferSizeInBytes];
try
{
InputStream inputStream = new FileInputStream(recordFile);
BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
DataInputStream dataInputStream = new DataInputStream(bufferedInputStream);
int i = 0;
while (dataInputStream.available() > 0)
{
audioData[i] = dataInputStream.readShort();
i++;
}
dataInputStream.close();
track = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT,
bufferSizeInBytes, AudioTrack.MODE_STREAM);
track.play();
track.write(audioData, 0, bufferSizeInBytes);
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
}
public class StartRecordListener implements View.OnClickListener
{
@Override
public void onClick(View v)
{
Thread recordThread = new Thread(new Runnable()
{
@Override
public void run()
{
isRecording = true;
MainActivity.this.startRecord();
}
});
recordThread.start();
startRecord.setEnabled(false);
stopRecord.setEnabled(true);
}
}
public class StopRecordListener implements View.OnClickListener
{
@Override
public void onClick(View v)
{
isRecording = false;
startRecord.setEnabled(true);
stopRecord.setEnabled(false);
}
}
public class PlayRecordListener implements View.OnClickListener
{
@Override
public void onClick(View v)
{
MainActivity.this.playRecord();
}
}
}
XML layout contains 3 buttons with the following ids: start_recording, stop_recording, play_recording
And add to following permissions:
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
Good luck and I hope it's okay for you, that I'm using 3 buttons in the code above.
来源：https://stackoverflow.com/questions/28013253/android-make-a-recorded-pcm-raw-data-playable