注意:我不想"读取音频文件foo.bar并播放它".
我想以编程方式动态生成音频文件并播放它们.
Java是否为此构建了库,还是属于依赖于系统的库？
谢谢!
tra*_*god 41
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;
public class Tone {
public static void main(String[] args) throws LineUnavailableException {
final AudioFormat af =
new AudioFormat(Note.SAMPLE_RATE, 8, 1, true, true);
SourceDataLine line = AudioSystem.getSourceDataLine(af);
line.open(af, Note.SAMPLE_RATE);
line.start();
for (Note n : Note.values()) {
play(line, n, 500);
play(line, Note.REST, 10);
}
line.drain();
line.close();
}
private static void play(SourceDataLine line, Note note, int ms) {
ms = Math.min(ms, Note.SECONDS * 1000);
int length = Note.SAMPLE_RATE * ms / 1000;
int count = line.write(note.data(), 0, length);
}
}
enum Note {
REST, A4, A4$, B4, C4, C4$, D4, D4$, E4, F4, F4$, G4, G4$, A5;
public static final int SAMPLE_RATE = 16 * 1024; // ~16KHz
public static final int SECONDS = 2;
private byte[] sin = new byte[SECONDS * SAMPLE_RATE];
Note() {
int n = this.ordinal();
if (n > 0) {
double exp = ((double) n - 1) / 12d;
double f = 440d * Math.pow(2d, exp);
for (int i = 0; i < sin.length; i++) {
double period = (double)SAMPLE_RATE / f;
double angle = 2.0 * Math.PI * i / period;
sin[i] = (byte)(Math.sin(angle) * 127f);
}
}
}
public byte[] data() {
return sin;
}
}
这种低级方法可能适用于较旧,功能较弱的平台.还要考虑javax.sound.midi; 一个完整的例子显示在这里和声音合成教程引用在这里.
小智 7
最简单的方法是在内置的MIDI库中使用java:
int channel = 0; // 0 is a piano, 9 is percussion, other channels are for other instruments
int volume = 80; // between 0 et 127
int duration = 200; // in milliseconds
try {
Synthesizer synth = MidiSystem.getSynthesizer();
synth.open();
MidiChannel[] channels = synth.getChannels();
// --------------------------------------
// Play a few notes.
// The two arguments to the noteOn() method are:
// "MIDI note number" (pitch of the note),
// and "velocity" (i.e., volume, or intensity).
// Each of these arguments is between 0 and 127.
channels[channel].noteOn( 60, volume ); // C note
Thread.sleep( duration );
channels[channel].noteOff( 60 );
channels[channel].noteOn( 62, volume ); // D note
Thread.sleep( duration );
channels[channel].noteOff( 62 );
channels[channel].noteOn( 64, volume ); // E note
Thread.sleep( duration );
channels[channel].noteOff( 64 );
Thread.sleep( 500 );
// --------------------------------------
// Play a C major chord.
channels[channel].noteOn( 60, volume ); // C
channels[channel].noteOn( 64, volume ); // E
channels[channel].noteOn( 67, volume ); // G
Thread.sleep( 3000 );
channels[channel].allNotesOff();
Thread.sleep( 500 );
synth.close();
}
catch (Exception e) {
e.printStackTrace();
}
Java 的内置 Midi 功能
现成的 Java 8 JRE 肯定有您特别要求的东西：内置合成库。合成声音中对其进行了详细描述。
一个相当精致的示例提供了对采样音乐合成器的可视键盘访问。
javax.sound.midi 库包含基于 MIDI 和采样乐器技术的乐器以及在其上演奏音符的能力。这些声音并不像经典的 Kurzweil 乐器系列那样真实，但如果您希望在单个乐器的多个音高范围内进行自己的采样并计算出相当无缝过渡的细节，则该框架支持这种复杂程度范围之间。
快速查看使用情况的简单示例
这是一个简单的示例类。
import javax.sound.midi.MidiSystem;
import javax.sound.midi.Synthesizer;
import javax.sound.midi.MidiChannel;
public class PlayMidiNote
{
private static void sleep(int iUSecs)
{
try
{
Thread.sleep(iUSecs);
}
catch (InterruptedException e)
{
}
}
public static void main(String[] args) throws Exception
{
if (args.length < 3 && args.length > 4)
{
System.out.println("usage: java PlayNote
<8.bit.midi.note.number> <8.bit.velocity>
<usec.duration> [<midi.channel>]");
System.exit(1);
}
int iMidiKey = Math.min(127, Math.max(0,
Integer.parseInt(args[0])));
int iVelocity = Math.min(127, Math.max(0,
Integer.parseInt(args[1])));
int iUSecsDuration = Math.max(0,
Integer.parseInt(args[2]));
int iChannel = args.length > 3
? Math.min(15, Math.max(0,
Integer.parseInt(args[3])))
: 0;
Synthesizer synth = MidiSystem.getSynthesizer();
synth.open();
MidiChannel[] channels = synth.getChannels();
MidiChannel channel = channels[iChannel];
channel.noteOn(iMidiKey, iVelocity);
sleep(iUSecsDuration);
channel.noteOff(iMidiKey);
synth.close();
}
}
使用多线程或 javax.sound.midi.Sequencer 的实现（如 GitHub.com 上提供的那些）将提供实际制作音乐所需的结构。
波形生成
如果您希望生成自己的波形而不是使用样本，那么您问题的答案是“否”，但是您可以使用我为此问题编写的音调合成器。它有几个特点。
该合成器缺乏高端波形生成合成器的许多功能。
SimpleSynth 很好地演示了
标准数字音频术语用于常量和变量命名。数学在评论中解释。
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.SourceDataLine;
class SimpleSynth
{
private static int SAMPLE_BITS = 16;
private static int CHANNELS = 1;
private static boolean SIGNED_TRUE = true;
private static boolean BIG_ENDIAN_FALSE = false;
private static float CDROM_SAMPLE_FREQ = 44100;
private SourceDataLine line;
private double dDuration;
private double dCyclesPerSec;
private double dAmplitude;
private double[] adHarmonics;
private double dMin;
private double dMax;
public SimpleSynth(String[] asArguments) throws Exception
{
dDuration = Double.parseDouble(asArguments[0]);
dCyclesPerSec = Double.parseDouble(asArguments[1]);
dAmplitude = Double.parseDouble(asArguments[2]);
adHarmonics = new double[asArguments.length - 3];
for (int i = 0; i < adHarmonics.length; ++ i)
adHarmonics[i] = Double.parseDouble(
asArguments[i + 3]);
AudioFormat format = new AudioFormat(
CDROM_SAMPLE_FREQ, SAMPLE_BITS,
CHANNELS, SIGNED_TRUE, BIG_ENDIAN_FALSE);
line = AudioSystem.getSourceDataLine(format);
line.open();
line.start();
}
public void closeLine()
{
line.drain();
line.stop();
}
public void playSound()
{
// allocate and prepare byte buffer and its index
int iBytes = (int) (2.0 * (0.5 + dDuration)
* CDROM_SAMPLE_FREQ);
byte[] ab = new byte[iBytes];
int i = 0;
// iterate through sample radian values
// for the specified duration
short i16;
double dSample;
double dRadiansPerSample = 2.0 * Math.PI
* dCyclesPerSec / CDROM_SAMPLE_FREQ;
double dDurationInRadians = 2.0 * Math.PI
* dCyclesPerSec * dDuration;
dMin = 0.0;
dMax = 0.0;
for (double d = 0.0;
d < dDurationInRadians;
d += dRadiansPerSample)
{
// add principle and the dot product of harmonics
// and their amplitudes relative to the principle
dSample = Math.sin(d);
for (int h = 0; h < adHarmonics.length; ++ h)
dSample += adHarmonics[h]
* Math.sin((h + 2) * d);
// factor in amplitude
dSample *= dAmplitude;
// adjust statistics
if (dMin > dSample)
dMin = dSample;
if (dMax < dSample)
dMax = dSample;
// store in byte buffer
i16 = (short) (dSample);
ab[i ++] = (byte) (i16);
ab[i ++] = (byte) (i16 >> 8);
}
// send the byte array to the audio line
line.write(ab, 0, i);
}
public void printStats()
{
System.out.println("sample range was ["
+ dMin + ", " + dMax + "]"
+ " in range of [-32768, 32767]");
if (dMin < -32768.0 || dMax > 32767.0)
System.out.println("sound is clipping"
+ "(exceeding its range),"
+ " so use a lower amplitude");
}
public static void main(String[] asArguments)
throws Exception
{
if (asArguments.length < 3)
{
System.err.println("usage: java SimpleSynth"
+ " <duration>"
+ " <tone.cycles.per.sec>"
+ " <amplitude>"
+ " [<relative.amplitude.harmonic.2>"
+ " [...]]");
System.err.println("pure tone:"
+ " java SimpleSynth 1 440 32767");
System.err.println("oboe-like:"
+ " java SimpleSynth 1 440 15000 0 1 0 .9");
System.err.println("complex:"
+ " java SimpleSynth 1 440 800 .3"
+ " .5 .4 .2 .9 .7 5 .1 .9 12 0 3"
+ " .1 5.2 2.5 .5 1 7 6");
System.exit(0);
}
SimpleSynth synth = new SimpleSynth(asArguments);
synth.playSound();
synth.closeLine();
synth.printStats();
System.exit(0);
}
}
增强音乐合成专业知识的研究主题
如果您想成为数字合成器专家，可以阅读一些主题。
这篇 Sun 论坛帖子有一些有趣的代码用于生成正弦音。此外，鉴于 WAV 文件格式不太复杂，您可以创建一个表示所需波形的表格，然后将其写入文件。有一些示例，例如原始音频转换器以及如何编写 wav 文件。
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