我使用Android的AudioRecord录制音频并将其保存到WAV文件中。问题是，当我从WAV文件播放音频时，听起来它是快速转发（播放太快）。在我发布的课程中，我也有语音识别设置。语音识别工作和音频记录，但它是音频播放的速率是不对的。
我认为这可能是我编写WAV文件的问题，但我不确定。可以在WAV标题中修改哪些设置或将音频写入wav文件，以使音频播放速度变慢？
这是我正在使用的课程。我省略了类中的一些方法来保持代码更具可读性。
public class SpeechRecognizer {
protected static final String TAG = SpeechRecognizer.class.getSimpleName();
private final Decoder decoder;
private final int sampleRate;
private int bufferSize;
private final AudioRecord recorder;
private boolean record;
private boolean is_recording;
/* Files to record the audio into */
public File pcm_sound_file;
public File wav_sound_file;
private Thread recognizerThread;
public Thread recorder_thread;
private final Handler mainHandler = new Handler(Looper.getMainLooper());
private final Collection<RecognitionListener> listeners = new HashSet<RecognitionListener>();
/**
* Creates speech recognizer. Recognizer holds the AudioRecord object, so you
* need to call {@link release} in order to properly finalize it.
*
* @param config The configuration object
* @throws IOException thrown if audio recorder can not be created for some reason.
*/
protected SpeechRecognizer(Config config, boolean record) throws IOException {
this.record = record;
decoder = new Decoder(config);
sampleRate = (int)decoder.getConfig().getFloat("-samprate");
bufferSize = AudioRecord.getMinBufferSize(sampleRate,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT);
recorder = new AudioRecord(
AudioSource.VOICE_RECOGNITION, sampleRate,
AudioFormat.CHANNEL_IN_MONO,
AudioFormat.ENCODING_PCM_16BIT, bufferSize);
if (recorder.getState() == AudioRecord.STATE_UNINITIALIZED) {
recorder.release();
throw new IOException(
"Failed to initialize recorder. Microphone might be already in use.");
}
}
/**
* Stops recognition. All listeners should receive final result if there is
* any. Does nothing if recognition is not active.
*
* @return true if recognition was actually stopped
*/
public boolean stop() {
boolean result = stopRecognizerThread();
if (result) {
Log.i(TAG, "Stop recognition");
is_recording = false;
recorder_thread = null;
try {
wav_sound_file = getOutputMediaFile("wav");
copyWaveFile(pcm_sound_file, wav_sound_file);
}
catch (Exception e){
Log.d("COS", "Failed to convert PCM to WAV");
}
final Hypothesis hypothesis = decoder.hyp();
mainHandler.post(new ResultEvent(hypothesis, true));
}
return result;
}
private void copyWaveFile(File inFilename,File outFilename){
FileInputStream in;
FileOutputStream out;
long totalAudioLen;
long totalDataLen;
long longSampleRate = sampleRate;
int channels = 1;
long byteRate = 16 * sampleRate * channels/8;
byte[] data = new byte[bufferSize];
try {
in = new FileInputStream(inFilename);
out = new FileOutputStream(outFilename);
totalAudioLen = in.getChannel().size();
totalDataLen = totalAudioLen + 36;
WriteWaveFileHeader(out, totalAudioLen, totalDataLen,
longSampleRate, channels, byteRate);
while(in.read(data) != -1){
out.write(data);
}
in.close();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
}
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) (16 / 8); // block align
header[33] = 0;
header[34] = 16; // 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);
}
private void writeAudioDataToFile() {
byte sData[] = new byte[bufferSize];
FileOutputStream os = null;
try {
pcm_sound_file = getOutputMediaFile("pcm");
os = new FileOutputStream(pcm_sound_file);
} catch (Exception e) {e.printStackTrace();}
while (is_recording) {
recorder.read(sData, 0, bufferSize);
try {
os.write(sData);
} catch (Exception e) {e.printStackTrace();}
}
try {
os.close();
} catch (Exception e) {e.printStackTrace();}
}
private File getOutputMediaFile(String format){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "SafePhrase");
// This location works best if you want the created images to be shared
// between applications and persist after your app has been uninstalled.
// Create the storage directory if it does not exist
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("COS", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"SOUND_"+ timeStamp + "." + format);
return mediaFile;
}
private final class RecognizerThread extends Thread {
private int remainingSamples;
private int timeoutSamples;
private final static int NO_TIMEOUT = -1;
public RecognizerThread(int timeout) {
if (timeout != NO_TIMEOUT)
this.timeoutSamples = timeout * sampleRate / 1000;
else
this.timeoutSamples = NO_TIMEOUT;
this.remainingSamples = this.timeoutSamples;
}
public RecognizerThread() {
this(NO_TIMEOUT);
}
@Override
public void run() {
recorder.startRecording();
/* If the user has asked to record, then create a new recorder thread where the audio
* will be recorded. */
if(record) {
recorder_thread = new Thread(new Runnable() {
@Override
public void run() {
Log.d("COS", "RECORDING!");
writeAudioDataToFile();
}
}, "Audio Recorder Thread");
recorder_thread.start();
}
else{
Log.d("COS", "NOT RECORDING!");
}
/* SPEECH RECOGNITION BELOW */
if (recorder.getRecordingState() == AudioRecord.RECORDSTATE_STOPPED) {
recorder.stop();
IOException ioe = new IOException(
"Failed to start recording. Microphone might be already in use.");
mainHandler.post(new OnErrorEvent(ioe));
return;
}
Log.d(TAG, "Starting decoding");
decoder.startUtt();
short[] buffer = new short[bufferSize];
boolean inSpeech = decoder.getInSpeech();
// Skip the first buffer, usually zeroes
recorder.read(buffer, 0, buffer.length);
while (!interrupted()
&& ((timeoutSamples == NO_TIMEOUT) || (remainingSamples > 0))) {
int nread = recorder.read(buffer, 0, buffer.length);
if (-1 == nread) {
throw new RuntimeException("error reading audio buffer");
} else if (nread > 0) {
decoder.processRaw(buffer, nread, false, false);
// int max = 0;
// for (int i = 0; i < nread; i++) {
// max = Math.max(max, Math.abs(buffer[i]));
// }
// Log.e("!!!!!!!!", "Level: " + max);
if (decoder.getInSpeech() != inSpeech) {
inSpeech = decoder.getInSpeech();
mainHandler.post(new InSpeechChangeEvent(inSpeech));
}
if (inSpeech)
remainingSamples = timeoutSamples;
final Hypothesis hypothesis = decoder.hyp();
mainHandler.post(new ResultEvent(hypothesis, false));
}
if (timeoutSamples != NO_TIMEOUT) {
remainingSamples = remainingSamples - nread;
}
}
recorder.stop();
decoder.endUtt();
// Remove all pending notifications.
mainHandler.removeCallbacksAndMessages(null);
// If we met timeout signal that speech ended
if (timeoutSamples != NO_TIMEOUT && remainingSamples <= 0) {
mainHandler.post(new TimeoutEvent());
}
}
}
答案 0 :(得分：0)
MediaPlayer 类不提供此功能，但 SoundPool 具有此功能。 SoundPool类有一个名为setRate(int streamID, float rate)的方法。如果您对API感兴趣请看这里。
此代码段将起作用：
float playbackSpeed=1.5f;
SoundPool soundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 100);
soundId = soundPool.load(Environment.getExternalStorageDirectory()
+ "/sample.wav", 1);
AudioManager manager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
final float volume = manager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
soundPool.setOnLoadCompleteListener(new OnLoadCompleteListener()
{
@Override
public void onLoadComplete(SoundPool arg0, int arg1, int arg2)
{
soundPool.play(soundId, volume, volume, 1, 0, playbackSpeed);
}
});