Android音频可视化开发案例说明

package eoe.demo;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Toast;
/**
* 被实例演示如何调用Android自带的应用来完成Audio的录入
* 其实很简单，我们需要指定一个MediaStore.Audio.Media.RECORD_SOUND_ACTION的Action来启动就可以
* 返回的Data数据就是我们录制的音频的URI了
*
* 通过上面这种方式，灵活性不够高，我们可以利用MediaRecorder类来实现自己的音频录制程序
* MediaRecorder既可以用来录制音频，也可以用来录制视频
* 创建了一个MediaRecorder实例后，需要调用setAudioSource和setAudioEncoder来初始化
* 通常情况下，在准备录制前，我们还需要调用setOutputFormat()方法来决定使用的音频格式，同时调用
* setOutputFile()来指定存放录制内容的文件
*
* 这几个方法的调用顺序是：setAudioSource,setOutputFormat,setAudioEncoder,setOutputFile
*
*
*
* @author Administrator
*
*/
public class AudioRecordDemo extends Activity {
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.audio_record);
}
public void onActivityResult(int requestCode, int resultCode, Intent data){
//super.onActivityResult(requestCode, resultCode, data);
//这里我们就可以获取到刚刚录制的音频的Uri，可以进行播放等操作，这里显示返回的Uri
if(resultCode == RESULT_OK){
Uri audioPath = data.getData();
Toast.makeText(this, audioPath.toString(), Toast.LENGTH_LONG).show();
}
}
public void onClick(View v){
int id = v.getId();
switch(id){
case R.id.btn1: //调用Android自带的音频录制应用
Intent intent = new Intent(MediaStore.Audio.Media.RECORD_SOUND_ACTION);
startActivityForResult(intent, 0);
break;
case R.id.btn2:
//通过MediaRecorder类来实现自己的音频录制程序
Intent intent2 = new Intent();
intent2.setClass(this, MyAudioRecord.class);
startActivityForResult(intent2, 1);
break;
case R.id.btn3:
//通过AudioRecord类实现自己的音频录制程序
Intent intent3 = new Intent();
intent3.setClass(this, MyAudioRecord2.class);
startActivityForResult(intent3, 2);
break;
}
}
}

hardware/libhardware_legacy/include/hardware_legacy/AudioHardwareInterface.h

frameworks/base/libs/audioflinger/AudioHardwareInterface.cpp

AudioHardwareInterface* AudioHardwareInterface::create()
{
/*
* FIXME: This code needs to instantiate the correct audio device
* interface. For now - we use compile-time switches.
*/
AudioHardwareInterface* hw = 0;
char value[PROPERTY_VALUE_MAX];
#ifdef GENERIC_AUDIO
hw = new AudioHardwareGeneric();
#elseif (property_get("ro.kernel.qemu", value, 0)) {
LOGD("Running in emulation - using generic audio driver");
hw = new AudioHardwareGeneric();
}
else {
LOGV("Creating Vendor Specific AudioHardware");
hw = createAudioHardware();
}
#endif
if (hw->initCheck() != NO_ERROR) {
LOGW("Using stubbed audio hardware. No sound will be produced.");
delete hw;
hw = new AudioHardwareStub();
}
#ifdef WITH_A2DP
hw = new A2dpAudioInterface(hw);
#endif
#ifdef ENABLE_AUDIO_DUMP
recorded in the file.
LOGV("opening PCM dump interface");
hw = new AudioDumpInterface(hw); // replace interface
#endif
return hw;
}

frameworks/base/libs/audioflinger/AudioHardwareGeneric.cpp

public class FFTActivity extends Activity implements OnClickListener{
private Button button;
private ImageView imageView;
private int frequency = 8000;
private int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;
private int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;
private RealDoubleFFT transformer;
private int blockSize = 256;
private boolean started = false;
private Canvas canvas;
private Paint paint;
private Bitmap bitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fft);
button = (Button) findViewById(R.id.fft_button);
button.setOnClickListener(this);
imageView = (ImageView) findViewById(R.id.fft_imageView);
transformer = new RealDoubleFFT(blockSize);
bitmap = Bitmap.createBitmap(256, 100, Bitmap.Config.ARGB_8888);
canvas = new Canvas(bitmap);
paint = new Paint();
paint.setColor(Color.GREEN);
imageView.setImageBitmap(bitmap);
}
private class RecordAudio extends AsyncTask<Void, double[], Void> {
@Override
protected Void doInBackground(Void... params) {
int bufferSize = AudioRecord.getMinBufferSize(frequency,
channelConfiguration, audioEncoding);
AudioRecord audioRecord = new AudioRecord(
MediaRecorder.AudioSource.MIC, frequency,
channelConfiguration, audioEncoding, bufferSize);
short[] buffer = new short[blockSize];
double[] toTransform = new double[blockSize];
audioRecord.startRecording();
while (started) {
//将record的数据 读到buffer中，但是我认为叫做write可能会比较合适些。
int bufferResult = audioRecord.read(buffer, 0, blockSize);
for (int i = 0; i < bufferResult; i++) {
toTransform<i> = (double) buffer<i> / Short.MAX_VALUE;
}
transformer.ft(toTransform);
publishProgress(toTransform);
}
audioRecord.stop();
return null;
}
@Override
protected void onProgressUpdate(double[]... values) {
super.onProgressUpdate(values);
canvas.drawColor(Color.BLACK);
for (int i = 0; i < values[0].length; i++) {
int x=i;
int downy=(int)(100-(values[0]<i>)*10);
int upy=100;
canvas.drawLine(x, downy, x, upy, paint);
}
imageView.invalidate();
}
}
@Override
public void onClick(View v) {
started=true;
new RecordAudio().execute();
}
}