我正在编写一个应用程序，使用4个MediaPlayer对象同时播放4个mp3文件。我添加了3个自定义旋钮，使用4个均衡器控制低音，中音和高音，每个均衡器连接到其特定的MediaPlayer。我已经验证我正在按照指定将正确的值（以毫巴为单位）传递给setBandLevel，但是在旋转控件时我听不到声音的任何差异。我在下面添加了相关代码。
我注意到的一件事似乎很奇怪，我调用的均衡器方法预计短路，但频率范围上限可以高达6,000,000毫贝。我可能在这里遗漏了一些东西，但是android中的短片是2 ^ 16，这应该意味着64k的上限。
public void setBandLevel（短波段，短波段）
代码运行时没有遇到异常，我跟踪所有值以验证每个频率是否在其波段范围内，但是当我旋转控制旋钮时，声音没有变化。我已经在K，L和M上测试过这个结果。
我很欣赏对此的任何见解。
public void onResume() {
super.onResume();
// Load an ad into the AdMob banner view.
AdView adView = (AdView) getView().findViewById(R.id.adView);
AdRequest adRequest = new AdRequest.Builder()
.setRequestAgent("android_studio:ad_template").build();
adView.loadAd(adRequest);
//initialize views
initializeViews();
setInstrumentNames();
mediaPlayer1.start();
mediaPlayer2.start();
mediaPlayer3.start();
mediaPlayer4.start();
// Start the songtime thread and remember its object so it can be stopped legally
play();
setEqualizer();
setupKnobButtons();
}
public void setEqualizer() {
eq1 = new Equalizer(0, mediaPlayer1.getAudioSessionId());
eq2 = new Equalizer(0, mediaPlayer2.getAudioSessionId());
eq3 = new Equalizer(0, mediaPlayer3.getAudioSessionId());
eq4 = new Equalizer(0, mediaPlayer4.getAudioSessionId());
if (eq1 != null && eq2 != null && eq3 != null && eq4 != null) {
int z = eq1.setEnabled(true);
int c = eq2.setEnabled(true);
int d = eq3.setEnabled(true);
int e = eq4.setEnabled(true);
// The number of bands is usually 5 but could be up to 13
num_bands = eq1.getNumberOfBands();
// The band range will always return the min and max
// Gets the level range for use by setBandLevel(short,short)}. The level is expressed in
// milliBel. Return the band level range in an array of short integers. The first element is the lower
// limit of the range, the second element the upper limit.
// --- THIS IS FOR THE FULL RANGE OF ALL BANDS ---///
range = eq1.getBandLevelRange();
min_level = range[0];
max_level = range[1];
Log.d(TAG_BANDLEVELS, "min level = " + min_level + " max level = " + max_level);
// Loop through all the bands ( usually 5 ) and create 2 arrays
// ( one for lower limit of each band and one for the upper )
for (int i = 0; i < num_bands; i++) {
freq_range = eq1.getBandFreqRange((short) i);
freqRangeLowerLimit.add(freq_range[0]);
freqRangeUpperLimit.add(freq_range[1]);
Log.d(TAG_BANDLEVELS, "freqRangeLowerLimit = " + freq_range[0] +
" freqRangeUpperLimit = " + freq_range[1] + " band = " + i);
}
}
}
private void setBandLevels(int percentage, int new_level1, int new_level2, int nBand) {
if (eq1.hasControl()) {
eq1.setBandLevel((short) nBand, (short) new_level1);
}
else
Log.d(TAG_BANDLEVELS, "EQ 1 DOES NOT HAVE CONTROL");
if (eq2.hasControl()) {
eq2.setBandLevel((short) nBand, (short) new_level1);
}
else
Log.d(TAG_BANDLEVELS, "EQ 2 DOES NOT HAVE CONTROL");
if (eq3.hasControl()) {
eq3.setBandLevel((short) nBand, (short) new_level1);
}
else
Log.d(TAG_BANDLEVELS, "EQ 3 DOES NOT HAVE CONTROL");
if (eq4.hasControl()) {
eq4.setBandLevel((short) nBand, (short) new_level1);
}
else
Log.d(TAG_BANDLEVELS, "EQ 4 DOES NOT HAVE CONTROL");
// Mid and Treble use 2 bands (Mid = 2nd and 3rd Treble = 4th and 5th
if (nBand == PlayFragment.BAND_BASS || nBand == PlayFragment.BAND_TREBLE) {
try {
eq1.setBandLevel((short) (nBand+1), (short) new_level2);
eq2.setBandLevel((short) (nBand+1), (short) new_level2);
eq3.setBandLevel((short) (nBand+1), (short) new_level2);
eq4.setBandLevel((short) (nBand+1), (short) new_level2);
} catch (Throwable ex2) {
ex2.printStackTrace();
}
}
}
public void setupKnobButtons() {
RoundKnobButton rnbBass = (RoundKnobButton) getView().findViewById(R.id.btRoundBass);
rnbBass.SetListener(new RoundKnobButtonListener() {
TextView tvEQBass = (TextView) getView().findViewById(R.id.tvEQBass);
public void onStateChange(boolean newstate) {
Toast.makeText(getActivity(), "New state:" + newstate, Toast.LENGTH_SHORT).show();
}
public void onRotate(final int percentage) {
tvEQBass.post(new Runnable() {
public void run() {
tvEQBass.setText("\n" + percentage + "%\n");
// Bass only uses the first band
int lower1 = freqRangeLowerLimit.get(0);
int upper1 = freqRangeUpperLimit.get(0);
int new_level1 = lower1 + ((upper1 - lower1) * percentage/100);
// new_level1 /= 1000;
// int new_level1 = calc1/100;
int lower2 = freqRangeLowerLimit.get(1);
int upper2 = freqRangeUpperLimit.get(1);
int new_level2 = lower1 + ((upper2 - lower2) * percentage/100);
// new_level2 /= 1000;
// int new_level2 = calc2/100;
setBandLevels(percentage, new_level1, new_level2, BAND_BASS);
Log.d(TAG_BANDLEVELS, "Band = Bass " + "New Level1 = " + new_level1 + "New Level2 = " + new_level2 + " Percentage = " + percentage);
}
});
}
});