JOAL学习笔记 第一课 单一固定声源

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JOAL学习笔记


最近一直在弄数字音频处理的一些东西,在网上检索到了OpenAL的相关资料,粗略阅读后感觉这个API还是很有魅力的,但JOAL教程的汉化版大多为低质量机翻,不太适合学习,于是决定自己翻译一下。

第一次尝试翻译英文技术原文,自己也就是六级水平,采用人脑为主词典为辅的方式。不期待有多高的翻译质量,只希望译文至少能够让读者连贯地读完并对其意义正确理解。

在翻译完每一节时,我会亲自调试一下课程中的程序实例,并在这里记录下值得注意的问题。

如果看过教程,一定发现了它的代码部分与文章部分融合到了一起,虽然易于解释,但对于复制调试来讲实在是不方便,因此在每篇对应的笔记中会有该实例对应的连续代码,以方便复制调试。


下面进入正题,首先是连续的代码

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.ByteBuffer;

import com.jogamp.openal.AL;
import com.jogamp.openal.ALFactory;
import com.jogamp.openal.util.ALut;

public class SingleStaticSource {
	static AL al = ALFactory.getAL();

	// Buffers hold sound data.
	static int[] buffer = new int[1];;

	// Sources are points emitting sound.
	static int[] source = new int[1];

	// Position of the source sound.
	static float[] sourcePos = { 0.0f,0.0f,0.0f };

	// Velocity of the source sound.
	static float[] sourceVel = { 0.0f,0.0f };

	// Position of the listener.
	static float[] listenerPos = { 0.0f,0.0f };

	// Velocity of the listener.
	static float[] listenerVel = { 0.0f,0.0f };

	// Orientation of the listener. (first 3 elements are "at",second 3 are
	// "up")
	static float[] listenerOri = { 0.0f,-1.0f,1.0f,0.0f };

	static int loadALData() {

		// variables to load into

		int[] format = new int[1];
		int[] size = new int[1];
		ByteBuffer[] data = new ByteBuffer[1];
		int[] freq = new int[1];
		int[] loop = new int[1];

		// Load wav data into a buffer.
		al.alGenBuffers(1,buffer,0);
		if (al.alGetError() != AL.AL_NO_ERROR)
			return AL.AL_FALSE;
		
		ALut.alutLoadWAVFile("wavdata/0201.wav",format,data,size,freq,loop);//这里设置你的Wav文件。
		al.alBufferData(buffer[0],format[0],data[0],size[0],freq[0]);

		// Bind buffer with a source.
		al.alGenSources(1,source,0);

		if (al.alGetError() != AL.AL_NO_ERROR)
			return AL.AL_FALSE;

		al.alSourcei(source[0],AL.AL_BUFFER,buffer[0]);
		al.alSourcef(source[0],AL.AL_PITCH,1.0f);
		al.alSourcef(source[0],AL.AL_GAIN,1.0f);
		al.alSourcefv(source[0],AL.AL_POSITION,sourcePos,0);
		al.alSourcefv(source[0],AL.AL_VELOCITY,sourceVel,0);
		al.alSourcei(source[0],AL.AL_LOOPING,loop[0]);
		// Do another error check and return.
		if (al.alGetError() == AL.AL_NO_ERROR)
			return AL.AL_TRUE;

		return AL.AL_FALSE;
	}

	static void setListenerValues() {
		al.alListenerfv(AL.AL_POSITION,listenerPos,0);
		al.alListenerfv(AL.AL_VELOCITY,listenerVel,0);
		al.alListenerfv(AL.AL_ORIENTATION,listenerOri,0);
	}

	static void killALData() {
		al.alDeleteBuffers(1,0);
		al.alDeleteSources(1,0);
		ALut.alutExit();
	}

	public static void main(String[] args) {
		// Initialize OpenAL and clear the error bit.
		ALut.alutInit();
		al.alGetError();
		// Load the wav data.
		if (loadALData() == AL.AL_FALSE)
			System.exit(-1);

		setListenerValues();

		// Setup an exit procedure.

		Runtime runtime = Runtime.getRuntime();
		runtime.addShutdownHook(new Thread(new Runnable() {
			public void run() {
				killALData();
			}
		}));
		char[] c = new char[1];
		while (c[0] != 'q') {
			try {
				BufferedReader buf = new BufferedReader(new InputStreamReader(
						System.in));
				System.out
						.println("Press a key and hit ENTER: "
								+ "'p' to play,'s' to stop,'h' to pause and 'q' to quit");
				buf.read(c);
				switch (c[0]) {
				case 'p':
					// Pressing 'p' will begin playing the sample.
					al.alSourcePlay(source[0]);
					break;
				case 's':
					// Pressing 's' will stop the sample from playing.
					al.alSourceStop(source[0]);
					break;
				case 'h':
					// Pressing 'n' will pause (hold) the sample.
					al.alSourcePause(source[0]);
					break;
				}
			} catch (IOException e) {
				System.exit(1);
			}
		}
	}
}


这里说明一些需要注意的地方

首先是JOAL依赖jar包的下载地址,这里给出:

http://jogamp.org/deployment/jogamp-current/archive/我下载的是全平台版本(all-platform)

之后是实例项目所依赖的最小项是哪些,笔者经过几次组合后确定了两个必须的jar包为:joal.jar和gluegen-rt.jar

在调试音频时我发现,音频的播放没有在JVM中创建新的线程:


至少不用再担心其与JVM内线程的安全问题了。

最后说句无关的,这个作者在文末冷不丁地来了一句黑客语,我不知道他出于什么目的提到这句话,但这句话显然让一大批机翻暴漏了,我也是Google查了一下才知道是什么意思。

原文链接:https://www.f2er.com/javaschema/285232.html

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