Java-在X位置启动音频播放

编辑：我使用的是.wav文件

我正在尝试找出如何在某个位置启动音频（例如：10秒进入音频文件，而不是在开始时）。阅读源数据线的文档时，我认为这可以通过使用偏移量来实现：

line.write（字节[]b，整数偏移量，整数长度）

但每次我尝试0以外的任何值（我相信是默认值），我都会得到java.lang.IndexOutOfBoundsException，它可能还没有读取x字节位置，所以无法写入x字节位置？我不确定，留下来挠头

我想这是一个很常见的请求，但似乎在网上找不到任何与此相关的内容，只有暂停和恢复音频。我可能没有正确地搜索

如果这很重要，以下是我目前如何制作音频：

     AudioInputStream stream = AudioSystem.getAudioInputStream("...file...");
     AudioFormat format = stream.getFormat();
     SourceDataLine.Info info = new DataLine.Info(SourceDataLine.class, format,((int)stream.getFrameLength()*format.getFrameSize()));
     SourceDataLine line = (SourceDataLine)AudioSystem.getLine(info);
     int bufferSize = line.getBufferSize();
     byte inBuffer[] = new byte[bufferSize];
     byte outBuffer[] = new byte[bufferSize];
     int numRead, numWritten;

     do {
         numRead = audioStream.read(inBuffer, 0, bufferSize);
            if(numRead <= 0) {
                myAudio.flushStream();
            } else {
                myAudio.writeBytesToStream(inBuffer, numRead);
            }
            do {
                numWritten = myAudio.readBytesFromStream(outBuffer, bufferSize);
                if(numWritten > 0) {
                    line.write(outBuffer, 0, numWritten);
                }
            } while(numWritten > 0);
        } while(numRead > 0);

AudioInputStream=AudioSystem.getAudioInputStream（“…文件…”）；
AudioFormat=stream.getFormat（）；
SourceDataLine.Info=newdataline.Info（SourceDataLine.class，format，（（int）stream.getFrameLength（）*format.getFrameSize（））；
SourceDataLine=（SourceDataLine）AudioSystem.getLine（info）；
int bufferSize=line.getBufferSize（）；
字节inBuffer[]=新字节[bufferSize]；
字节溢出器[]=新字节[bufferSize]；
int numRead，numwrited；
做{
numRead=audioStream.read（inBuffer，0，bufferSize）；
if（numRead 0）{
行写入（突发，0，numwrited）；
}
}而（numwrited>0）；
}而（numRead>0）；

您遇到的问题可能是由于您在调整

偏移量时没有调整
长度。如果数组的长度为10字节，并且开始从偏移量5（而不是0）读取10字节，则读取的字节数超过了其末尾

我建议首先跳过上使用的适当字节数，然后写入该行

AudioInputStream stream = AudioSystem.getAudioInputStream("...file...");
AudioFormat format = stream.getFormat();
// find out how many bytes you have to skip, this depends on bytes per frame (a.k.a. frameSize)
int secondsToSkip = 10;
long bytesToSkip = format.getFrameSize() * ((int)format.getFrameRate()) * secondsToSkip;
// now skip until the correct number of bytes have been skipped
int justSkipped = 0;
while (bytesToSkip > 0 && (justSkipped = stream.skip(bytesToSkip)) > 0) {
    bytesToSkip -= justSkipped;
}
// then proceed with writing to your line like you have done before
[...]

请注意，这仅在音频文件未压缩时有效。如果您正在处理类似于
.mp3
的内容，首先必须将流转换为（请参见）
我创建了一个编译并运行的示例。您可以从任何时间点播放.wav文件。它应该也适用于mp3文件，但我还没有测试过。为此调用mp3ToWav（）

import javax.sound.sampled.*;
import java.io.File;
import java.io.IOException;

public class PlayWavAtTimePoint {

    public static void main(String[] args) throws Exception {
        String fileName = args[0];
        int secondsToSkip = (Integer.parseInt(args[1]));

        PlayWavAtTimePoint program = new PlayWavAtTimePoint();
        AudioInputStream is = program.getAudioInputStream(fileName);
        program.skipFromBeginning(is, secondsToSkip);
        program.playSound(is);
    }

    private static void skipFromBeginning(AudioInputStream audioStream, int secondsToSkip) throws UnsupportedAudioFileException, IOException, LineUnavailableException {
        AudioFormat format = audioStream.getFormat();

        // find out how many bytes you have to skip, this depends on bytes per frame (a.k.a. frameSize)
        long bytesToSkip = format.getFrameSize() * ((int)format.getFrameRate()) * secondsToSkip;


        // now skip until the correct number of bytes have been skipped
        long justSkipped = 0;
        while (bytesToSkip > 0 && (justSkipped = audioStream.skip(bytesToSkip)) > 0) {
            bytesToSkip -= justSkipped;
        }
    }


    private static final int BUFFER_SIZE = 128000;


    /**
     * @param filename the name of the file that is going to be played
     */
    public void playSound(String filename) throws IOException, UnsupportedAudioFileException, LineUnavailableException {
        AudioInputStream audioStream = getAudioInputStream(filename);
        playSound(audioStream);
    }

    private AudioInputStream getAudioInputStream(String filename) throws UnsupportedAudioFileException, IOException {
        return AudioSystem.getAudioInputStream(new File(filename));
    }

    public void playSound(AudioInputStream audioStream) throws LineUnavailableException, IOException {
        AudioFormat audioFormat = audioStream.getFormat();
        DataLine.Info info = new DataLine.Info(SourceDataLine.class, audioFormat);
        SourceDataLine audioOutput = (SourceDataLine) AudioSystem.getLine(info);
        audioOutput.open(audioFormat);
        audioOutput.start();

        //This seems to be reading the whole file into a buffer before playing ... not efficient.
        //Why not stream it?
        int nBytesRead = 0;

        byte[] abData = new byte[BUFFER_SIZE];
        while (nBytesRead != -1) {
                nBytesRead = audioStream.read(abData, 0, abData.length);
            if (nBytesRead >= 0) {
                audioOutput.write(abData, 0, nBytesRead);
            }
        }

        audioOutput.drain();
        audioOutput.close();
    }

    /**
     * Invoke this function to convert to a playable file.
     */
    public static void mp3ToWav(File mp3Data) throws UnsupportedAudioFileException, IOException {
        // open stream
        AudioInputStream mp3Stream = AudioSystem.getAudioInputStream(mp3Data);
        AudioFormat sourceFormat = mp3Stream.getFormat();
        // create audio format object for the desired stream/audio format
        // this is *not* the same as the file format (wav)
        AudioFormat convertFormat = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,
                sourceFormat.getSampleRate(), 16,
                sourceFormat.getChannels(),
                sourceFormat.getChannels() * 2,
                sourceFormat.getSampleRate(),
                false);
        // create stream that delivers the desired format
        AudioInputStream converted = AudioSystem.getAudioInputStream(convertFormat, mp3Stream);
        // write stream into a file with file format wav
        AudioSystem.write(converted, AudioFileFormat.Type.WAVE, new File("/tmp/out.wav"));
    }
}

请指定文件格式。这是压缩音频文件（例如
.mp3
）还是未压缩格式（例如
.wav
）？编辑：我使用的是.wav文件，如果您先阅读整个文件会怎么样？：>我可能需要您解释，但如果您的意思是将整个文件加载到暂存区域，然后播放，我不确定这是否有效。基本上，我正在动态调整音频（速度和音量），因此每次更改时，我都需要使用新值读取音频文件并立即播放。如果我先读取整个文件，我想在等待读取时音频中会有间隙，不是吗？请发布编译的代码。什么是“myAudio”和“audioStream”。在您的示例中，这些都没有实例化。我想用你的代码跳到.wav文件中的某个时间点。