I'm developing an Android application, which supports audio recording with the following code, sample can be found here:
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:
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
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));
}