Android 音频录制为 wav
Android Audio Record to wav
我在 Android 上使用录音机录制了一段音频，它生成了一个原始 PCM 文件。我正在尝试将其转换为我可以收听的格式（例如 wav 或 mp3。
我已经从这个例子开始，但不知道从哪里开始：Android AudioRecord example
试过以下这些：
http://computermusicblog.com/blog/2008/08/29/reading-and-writing-wav-files-in-java
Recording .Wav with Android AudioRecorder
这是我要记录的代码（请注意，我正在使用倒数计时器来告诉它何时开始和停止记录。
public class AudioRecordService extends Service {
Toast toast;
private static final int RECORDER_SAMPLERATE = 44100;
private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
private AudioRecord record = null;
int BufferElements2Rec = 1024; // want to play 2048 (2K) since 2 bytes we use only 1024
int BytesPerElement = 2; // 2 bytes in 16bit format
private Thread recordingThread = null;
private boolean isRecording = false;
int buffsize = 0;
public AudioRecordService() {
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
public int onStartCommand(Intent intent, int flags, int startId)
{
try {
buffsize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
record = new AudioRecord(MediaRecorder.AudioSource.MIC,
RECORDER_SAMPLERATE, RECORDER_CHANNELS,
RECORDER_AUDIO_ENCODING, buffsize);
record.startRecording();
CountDownTimer countDowntimer = new CountDownTimer(15000, 1000) {
public void onTick(long millisUntilFinished) {
toast = Toast.makeText(AudioRecordService.this, "Recording", Toast.LENGTH_SHORT);
toast.show();
isRecording = true;
recordingThread = new Thread(new Runnable() {
public void run() {
writeAudioDataToFile();
}
}, "AudioRecorder Thread");
recordingThread.start();
}
public void onFinish() {
try {
toast.cancel();
Toast.makeText(AudioRecordService.this, "Done Recording ", Toast.LENGTH_SHORT).show();
isRecording = false;
record.stop();
record.release();
record = null;
recordingThread = null;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}};
countDowntimer.start();
}
catch (Exception ex)
{
ex.printStackTrace();
}
return Service.START_STICKY;
}
private byte[] short2byte(short[] sData) {
int shortArrsize = sData.length;
byte[] bytes = new byte[shortArrsize * 2];
for (int i = 0; i < shortArrsize; i++) {
bytes[i * 2] = (byte) (sData[i] & 0x00FF);
bytes[(i * 2) + 1] = (byte) (sData[i] >> 8);
sData[i] = 0;
}
return bytes;
}
private void writeAudioDataToFile() {
try {
//String filePath = "/sdcard/voice8K16bitmono.pcm";
String extState = Environment.getExternalStorageState();
// Path to write files to
String path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC + "/test").getAbsolutePath();
String fileName = "audio.pcm";
String externalStorage = Environment.getExternalStorageDirectory().getAbsolutePath();
File file = new File(externalStorage + File.separator + fileName);
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
short sData[] = new short[BufferElements2Rec];
FileOutputStream os = null;
try {
os = new FileOutputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
while (isRecording) {
// gets the voice output from microphone to byte format
record.read(sData, 0, BufferElements2Rec);
System.out.println("Short wirting to file" + sData.toString());
try {
// // writes the data to file from buffer
// // stores the voice buffer
byte bData[] = short2byte(sData);
os.write(bData, 0, BufferElements2Rec * BytesPerElement);
} catch (IOException e) {
e.printStackTrace();
}
}
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
catch (Exception ex) {
ex.printStackTrace();
}
}
}
我的 audio.pcm 已创建。但是我不知道怎么玩。我假设 bDate[] 是正在写入的字节数组。我创建的链接说他们使用了这些文件，但没有显示如何完成的示例。
如果重要的话，我已经使用 GoldWave 打开了文件。它可以打开，但音频很乱。
我还注意到我的文件是 2 秒，我认为这是因为 BytesPerElement 和 BufferElements2Rec。如果你能帮助我，那么 15 秒就太好了。
提前致谢！
PCM 文件和 WAV 文件之间的唯一区别是 PCM 文件没有 header 而 WAV 文件有。 WAV header 具有播放的关键信息，例如采样率、每个样本的位数和通道数。当您加载 PCM 文件时，应用程序必须事先知道此信息，或者您必须告诉它。例如，如果您将 PCM 文件加载到 audacity 中，它会提示您填写所有这些内容。
为了使现有的保存文件成为 .WAV，您需要在前面加上适当的 header。我不打算详细介绍它，因为已经有很多关于 SO 的详细答案，而且它很容易在网上找到 (https://en.wikipedia.org/wiki/WAV)
你提出的关于文件长度的第二个问题可能与以下事实有关：AudioRecord.read returns 一个整数，它是实际读取的样本数，因为它可能比你少要求。不过这确实是第二个问题
这是从 OMRECORDER:
中提取的示例 .WAV Header 格式
private byte[] wavFileHeader(long totalAudioLen, long totalDataLen, long longSampleRate,
int channels, long byteRate, byte bitsPerSample) {
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) (channels * (bitsPerSample / 8)); //
// block align
header[33] = 0;
header[34] = bitsPerSample; // 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);
return header;
}
下面是从 WhatsappAudioRecorder 中提取的 .aac 的 Header 格式：
private byte[] createAdtsHeader(int length) {
int frameLength = length + 7;
byte[] adtsHeader = new byte[7];
adtsHeader[0] = (byte) 0xFF; // Sync Word
adtsHeader[1] = (byte) 0xF1; // MPEG-4, Layer (0), No CRC
adtsHeader[2] = (byte) ((MediaCodecInfo.CodecProfileLevel.AACObjectLC - 1) << 6);
adtsHeader[2] |= (((byte) SAMPLE_RATE_INDEX) << 2);
adtsHeader[2] |= (((byte) CHANNELS) >> 2);
adtsHeader[3] = (byte) (((CHANNELS & 3) << 6) | ((frameLength >> 11) & 0x03));
adtsHeader[4] = (byte) ((frameLength >> 3) & 0xFF);
adtsHeader[5] = (byte) (((frameLength & 0x07) << 5) | 0x1f);
adtsHeader[6] = (byte) 0xFC;
return adtsHeader;
}
我在 Android 上使用录音机录制了一段音频，它生成了一个原始 PCM 文件。我正在尝试将其转换为我可以收听的格式（例如 wav 或 mp3。
我已经从这个例子开始，但不知道从哪里开始：Android AudioRecord example
试过以下这些： http://computermusicblog.com/blog/2008/08/29/reading-and-writing-wav-files-in-java
Recording .Wav with Android AudioRecorder
这是我要记录的代码（请注意，我正在使用倒数计时器来告诉它何时开始和停止记录。
public class AudioRecordService extends Service {
Toast toast;
private static final int RECORDER_SAMPLERATE = 44100;
private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
private AudioRecord record = null;
int BufferElements2Rec = 1024; // want to play 2048 (2K) since 2 bytes we use only 1024
int BytesPerElement = 2; // 2 bytes in 16bit format
private Thread recordingThread = null;
private boolean isRecording = false;
int buffsize = 0;
public AudioRecordService() {
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
public int onStartCommand(Intent intent, int flags, int startId)
{
try {
buffsize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
record = new AudioRecord(MediaRecorder.AudioSource.MIC,
RECORDER_SAMPLERATE, RECORDER_CHANNELS,
RECORDER_AUDIO_ENCODING, buffsize);
record.startRecording();
CountDownTimer countDowntimer = new CountDownTimer(15000, 1000) {
public void onTick(long millisUntilFinished) {
toast = Toast.makeText(AudioRecordService.this, "Recording", Toast.LENGTH_SHORT);
toast.show();
isRecording = true;
recordingThread = new Thread(new Runnable() {
public void run() {
writeAudioDataToFile();
}
}, "AudioRecorder Thread");
recordingThread.start();
}
public void onFinish() {
try {
toast.cancel();
Toast.makeText(AudioRecordService.this, "Done Recording ", Toast.LENGTH_SHORT).show();
isRecording = false;
record.stop();
record.release();
record = null;
recordingThread = null;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}};
countDowntimer.start();
}
catch (Exception ex)
{
ex.printStackTrace();
}
return Service.START_STICKY;
}
private byte[] short2byte(short[] sData) {
int shortArrsize = sData.length;
byte[] bytes = new byte[shortArrsize * 2];
for (int i = 0; i < shortArrsize; i++) {
bytes[i * 2] = (byte) (sData[i] & 0x00FF);
bytes[(i * 2) + 1] = (byte) (sData[i] >> 8);
sData[i] = 0;
}
return bytes;
}
private void writeAudioDataToFile() {
try {
//String filePath = "/sdcard/voice8K16bitmono.pcm";
String extState = Environment.getExternalStorageState();
// Path to write files to
String path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC + "/test").getAbsolutePath();
String fileName = "audio.pcm";
String externalStorage = Environment.getExternalStorageDirectory().getAbsolutePath();
File file = new File(externalStorage + File.separator + fileName);
// if file doesnt exists, then create it
if (!file.exists()) {
file.createNewFile();
}
short sData[] = new short[BufferElements2Rec];
FileOutputStream os = null;
try {
os = new FileOutputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
while (isRecording) {
// gets the voice output from microphone to byte format
record.read(sData, 0, BufferElements2Rec);
System.out.println("Short wirting to file" + sData.toString());
try {
// // writes the data to file from buffer
// // stores the voice buffer
byte bData[] = short2byte(sData);
os.write(bData, 0, BufferElements2Rec * BytesPerElement);
} catch (IOException e) {
e.printStackTrace();
}
}
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
catch (Exception ex) {
ex.printStackTrace();
}
}
}
我的 audio.pcm 已创建。但是我不知道怎么玩。我假设 bDate[] 是正在写入的字节数组。我创建的链接说他们使用了这些文件，但没有显示如何完成的示例。
如果重要的话，我已经使用 GoldWave 打开了文件。它可以打开，但音频很乱。
我还注意到我的文件是 2 秒，我认为这是因为 BytesPerElement 和 BufferElements2Rec。如果你能帮助我，那么 15 秒就太好了。
提前致谢！
PCM 文件和 WAV 文件之间的唯一区别是 PCM 文件没有 header 而 WAV 文件有。 WAV header 具有播放的关键信息，例如采样率、每个样本的位数和通道数。当您加载 PCM 文件时，应用程序必须事先知道此信息，或者您必须告诉它。例如，如果您将 PCM 文件加载到 audacity 中，它会提示您填写所有这些内容。
为了使现有的保存文件成为 .WAV，您需要在前面加上适当的 header。我不打算详细介绍它，因为已经有很多关于 SO 的详细答案，而且它很容易在网上找到 (https://en.wikipedia.org/wiki/WAV)
你提出的关于文件长度的第二个问题可能与以下事实有关：AudioRecord.read returns 一个整数，它是实际读取的样本数，因为它可能比你少要求。不过这确实是第二个问题
这是从 OMRECORDER:
中提取的示例.WAV Header 格式
private byte[] wavFileHeader(long totalAudioLen, long totalDataLen, long longSampleRate,
int channels, long byteRate, byte bitsPerSample) {
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) (channels * (bitsPerSample / 8)); //
// block align
header[33] = 0;
header[34] = bitsPerSample; // 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);
return header;
}
下面是从 WhatsappAudioRecorder 中提取的 .aac 的 Header 格式：
private byte[] createAdtsHeader(int length) {
int frameLength = length + 7;
byte[] adtsHeader = new byte[7];
adtsHeader[0] = (byte) 0xFF; // Sync Word
adtsHeader[1] = (byte) 0xF1; // MPEG-4, Layer (0), No CRC
adtsHeader[2] = (byte) ((MediaCodecInfo.CodecProfileLevel.AACObjectLC - 1) << 6);
adtsHeader[2] |= (((byte) SAMPLE_RATE_INDEX) << 2);
adtsHeader[2] |= (((byte) CHANNELS) >> 2);
adtsHeader[3] = (byte) (((CHANNELS & 3) << 6) | ((frameLength >> 11) & 0x03));
adtsHeader[4] = (byte) ((frameLength >> 3) & 0xFF);
adtsHeader[5] = (byte) (((frameLength & 0x07) << 5) | 0x1f);
adtsHeader[6] = (byte) 0xFC;
return adtsHeader;
}