Question

android系统音量为什么要+5/10

Answer 1

调整音量方法有两种,一种是渐进式,即像手动按音量键一样,一步一步增加或减少,另一种是直接设置音量值.

1、渐进式

public void adjustStreamVolume (int streamType, int direction, int flags)

am.adjustStreamVolume (AudioManager.STREAM_MUSIC, AudioManager.ADJUST_RAISE, AudioManager.FLAG_SHOW_UI);
解释一下三个参数

第一个streamType是需要调整音量的类型,这里设的是媒体音量,可以是:
STREAM_ALARM 警报
STREAM_MUSIC 音乐回放即媒体音量
STREAM_NOTIFICATION 窗口顶部状态栏Notification,
STREAM_RING 铃声
STREAM_SYSTEM 系统
STREAM_VOICE_CALL 通话
STREAM_DTMF 双音多频,不是很明白什么东西

第二个direction,是调整的方向,增加或减少,可以是:
ADJUST_LOWER 降低音量
ADJUST_RAISE 升高音量
ADJUST_SAME 保持不变,这个主要用于向用户展示当前的音量

第三个flags是一些附加参数,只介绍两个常用的
FLAG_PLAY_SOUND 调整音量时播放声音
FLAG_SHOW_UI 调整时显示音量条,就是按音量键出现的那个
2、直接设置音量值的方法:

public void setStreamVolume (int streamType, int index, int flags)

am.setStreamVolume(AudioManager.STREAM_MUSIC, am.getStreamMaxVolume(AudioManager.STREAM_MUSIC), AudioManager.FLAG_PLAY_SOUND);
am.getStreamMaxVolume(AudioManager.STREAM_VOICE_CALL);//得到听筒模式的最大值
am.getStreamVolume(AudioManager.STREAM_VOICE_CALL);//得到听筒模式的当前值
第一个和第三个参数与上面的相同

第二个参数是一个音量的int值,getStreamMaxVolume(int streamType)得到的是该类型音量的最大值,可以根据这个值计算你需要的音量,我这里直接调到最大.

最后我的代码：

package com.lp;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import Android.app.Activity;
import Android.content.Context;
import Android.media.AudioFormat;
import Android.media.AudioManager;
import Android.media.AudioTrack;
import Android.os.Bundle;
import Android.view.View;
import Android.view.View.OnClickListener;
import Android.widget.Button;
import Android.widget.SeekBar;
/**
* AudioTrack 播放音频 如wav格式
* 并允许调节音量
* @author Administrator
*
*/
public class MainActivity5 extends Activity {
private Button play;
private Button stop;
private SeekBar soundValue;

private AudioTrack at;
private AudioManager am;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_sk);
am = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
play = (Button)findViewById(R.id.main_sk_play);
stop = (Button)findViewById(R.id.main_sk_stop);
soundValue = (SeekBar)findViewById(R.id.skbVolume);
setVolumeControlStream(AudioManager.STREAM_VOICE_CALL);
play.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {

if(am.isSpeakerphoneOn()){
am.setSpeakerphoneOn(false);
}
//setVolumeControlStream(AudioManager.STREAM_VOICE_CALL);
am.setMode(AudioManager.MODE_IN_CALL);
System.out.println(am.getStreamMaxVolume(AudioManager.STREAM_VOICE_CALL));
System.out.println("&&&&&&&&&&&&&");
System.out.println(am.getStreamVolume(AudioManager.STREAM_VOICE_CALL));
//am.setStreamVolume(streamType, index, flags)

int bufferSizeInBytes = AudioTrack.getMinBufferSize(44100, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);

if(at==null){
at = new AudioTrack(AudioManager.STREAM_VOICE_CALL, 44100, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSizeInBytes, AudioTrack.MODE_STREAM);
System.out.println("22222");
//at.setStereoVolume(100f, 100f);
at.setStereoVolume(0.7f, 0.7f);//设置当前音量大小
new AudioTrackThread().start();
}else{
if(at.getPlayState()==AudioTrack.PLAYSTATE_PLAYING){
System.out.println("111111111");
}else{
System.out.println("33333");
at = new AudioTrack(AudioManager.STREAM_VOICE_CALL, 44100, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSizeInBytes, AudioTrack.MODE_STREAM);
new AudioTrackThread().start();
}
}

}
});

stop.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
if(at.getPlayState()==AudioTrack.PLAYSTATE_PLAYING){
try{
at.stop();
}catch (IllegalStateException e)
{
e.printStackTrace();
}
at.release();
am.setMode(AudioManager.MODE_NORMAL);
}
}
});

// soundValue.setMax(100);//音量调节的极限
// soundValue.setProgress(70);//设置seekbar的位置值
soundValue.setMax(am.getStreamMaxVolume(AudioManager.STREAM_VOICE_CALL));
soundValue.setProgress(am.getStreamVolume(AudioManager.STREAM_VOICE_CALL));

soundValue.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
// float vol=(float)(seekBar.getProgress())/(float)(seekBar.getMax());
// System.out.println(vol);
// at.setStereoVolume(vol, vol);//设置音量
am.setStreamVolume(AudioManager.STREAM_VOICE_CALL, seekBar.getProgress(), AudioManager.FLAG_PLAY_SOUND);
}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}

@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// TODO Auto-generated method stub
}
});
}

class AudioTrackThread extends Thread{

@Override
public void run() {
byte[] out_bytes = new byte[44100];

InputStream is = getResources().openRawResource(R.raw.start);
int length ;
try{
at.play();
}catch (IllegalStateException e)
{
e.printStackTrace();
}
try {
while((length = is.read(out_bytes))!=-1){
//System.out.println(length);
at.write(out_bytes, 0, length);
}
} catch (IOException e) {
e.printStackTrace();
}
if(at.getPlayState()==AudioTrack.PLAYSTATE_PLAYING){
try{
at.stop();
}catch (IllegalStateException e)
{
e.printStackTrace();
}
at.release();
am.setMode(AudioManager.MODE_NORMAL);
}
}

}

}
当然 权限

<uses-permission Android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission Android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission Android:name="android.permission.RECORD_AUDIO" />

Answer 2

我也很难理解，改了AudioService的MaxValume数组，但是却没有效果，难过