需求说明

需要根据时间切割mp3、wav文件
切割：列如一个时常2分钟的mp3，需要保留XX秒后的音频数据，XX秒之前则丢弃
合并：需要在MP3或wav歌曲播放之前写入指定音频，将其连在一起

技术实现

环境准备

该工具为了快速实现本地化功能，采用了javafx8
在切割MP3和WAV时使用到了第三方库jaudiotagger
pom依赖：

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<!-- https://mvnrepository.com/artifact/net.jthink/jaudiotagger -->
<dependency>
    <groupId>net.jthink</groupId>
    <artifactId>jaudiotagger</artifactId>
    <version>3.0.1</version>
</dependency>

在合并时可能出现音频格式不一致，由于jaudiotagger没有发现针对mp3音频格式控制的接口暴露，所以采用了FFmpeg，使用javaac集成包
添加pom依赖

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<!-- https://mvnrepository.com/artifact/org.bytedeco/javacv-platform -->
<dependency>
    <groupId>org.bytedeco</groupId>
    <artifactId>javacv-platform</artifactId>
    <version>1.5.9</version>
</dependency>

核心功能实现

mp3切割实现：

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/**
 * 
 * @param music 需要切割的mp3文件
 * @param savePath 保存路径
 * @param time 切割时间
 * @return
 */
public File cutMusicByTime(File music, String savePath, long time) {
    //预备开始截取的时间
    long beginTime = time * 1000;
    //原mp3文件
    MP3File mp3 = new MP3File(music);
    MP3AudioHeader header = (MP3AudioHeader) mp3.getAudioHeader();
    int length = header.getTrackLength() ;
    //截取结算时间
    long endTime = length * 1000;
    long bitRateKbps = header.getBitRateAsNumber();
    // 1KByte/s=8Kbps, bitRate *1024L / 8L / 1000L 转换为 bps 每毫秒
    // 计算出开始字节位置
    long beginBitRateBpm = (bitRateKbps* 1024L / 8L / 1000L) * beginTime;
    // 返回音乐数据的第一个字节
    long firstFrameByte = header.getMp3StartByte();
    // 获取开始时间所在文件的字节位置
    long beginByte = firstFrameByte + beginBitRateBpm;
    // 计算出结束字节位置
    long endByte = beginByte +  (bitRateKbps* 1024L / 8L / 1000L)  * (endTime - beginTime);
    //目标文件
    File dFile = new File(savePath);
    RandomAccessFile dRaf = new RandomAccessFile(dFile, &quot;rw&quot;);
    RandomAccessFile sRaf = new RandomAccessFile(music, &quot;rw&quot;);
    //先将mp3的头文件写入文件
    for(long i = 0; i&lt; firstFrameByte;i++){
        int m = sRaf.read();
        dRaf.write(m);
    }
    //跳转到指定的位置
    sRaf.seek(beginByte);
    //开始写入 mp3实体
    for(long i = 0; i&lt;= endByte-beginByte ;i++){
        int m = sRaf.read();
        dRaf.write(m);
    }
    sRaf.close();
    dRaf.close();
    return dFile;
}

mp3合并实现:

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public static void convertAudioParameters(String fileAPath, String fileBPath, String outputPath)
        throws FrameGrabber.Exception, FrameRecorder.Exception {

    FFmpegFrameGrabber grabberA = new FFmpegFrameGrabber(fileAPath);
    FFmpegFrameGrabber grabberB = new FFmpegFrameGrabber(fileBPath);
    grabberA.start();
    grabberB.start();
    FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(outputPath, grabberB.getAudioChannels());
    //写入采样率
    recorder.setSampleRate(grabberB.getSampleRate());
    //写入音频码率
    recorder.setAudioBitrate(grabberB.getAudioBitrate());
    //复制tag
    for (Map.Entry&lt;String, String&gt; entry : grabberB.getMetadata().entrySet()) {
        recorder.setMetadata(entry.getKey(),entry.getValue());
    }
    recorder.start();
    Frame frameA;
    Frame frameB;
    //写入A文件
    while ((frameA = grabberA.grab()) != null) {
        recorder.record(frameA);
    }
    //写入B文件
    while ((frameB = grabberB.grab()) != null) {
        recorder.record(frameB);
    }
    grabberA.stop();
    grabberB.stop();
    recorder.stop();
}

wav切割实现：

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public File cutMusicByTime(File inputFile, String savePath, long time) {
    AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(inputFile);

    int bytesPerFrame = audioInputStream.getFormat().getFrameSize();
    int frameRate = (int) audioInputStream.getFormat().getFrameRate();
    audioInputStream.skip(time * frameRate * bytesPerFrame);
    long lengthToRead = audioInputStream.getFrameLength() * bytesPerFrame;
    AudioInputStream shortenedStream = new AudioInputStream(
            audioInputStream,
            audioInputStream.getFormat(),
            lengthToRead / bytesPerFrame
    );
    File outputFile = new File(savePath);
    AudioSystem.write(shortenedStream, AudioFileFormat.Type.WAVE, outputFile);
    copyAlbumInformation(inputFile, outputFile);
    return outputFile;
}
private static void copyAlbumInformation(File sourceFile, File outputFile)
        throws UnsupportedAudioFileException, IOException, TagException, ReadOnlyFileException, CannotWriteException, CannotReadException, InvalidAudioFrameException {
    AudioFile sourceAudioFile = AudioFileIO.read(sourceFile);
    Tag sourceTag = sourceAudioFile.getTag();
    AudioHeader audioHeader = sourceAudioFile.getAudioHeader();
    if (sourceTag != null) {
        AudioFile outputAudioFile = AudioFileIO.read(outputFile);
        Tag outputTag = outputAudioFile.getTag();
        Iterator&lt;TagField&gt; fields = sourceTag.getFields();
        while (fields.hasNext()){
            TagField tagField = fields.next();
            outputTag.setField(tagField);
        }
        outputAudioFile.commit();
    }
}

wav合并实现：

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public void mergeWAV(File inputFile1, File inputFile2, String outputFilePath) throws IOException, UnsupportedAudioFileException {
    AudioInputStream audioInputStream1 = AudioSystem.getAudioInputStream(inputFile1);
    AudioInputStream audioInputStream2 = AudioSystem.getAudioInputStream(inputFile2);

    AudioFormat format1 = audioInputStream1.getFormat();
    AudioFormat format2 = audioInputStream2.getFormat();

    if (!format1.matches(format2)) {
        audioInputStream1 = AudioSystem.getAudioInputStream(format2, audioInputStream1);
        format1 = audioInputStream1.getFormat();
    }

    AudioInputStream appendedFiles = new AudioInputStream(
            new SequenceInputStream(audioInputStream1, audioInputStream2),
            format1,
            audioInputStream1.getFrameLength() + audioInputStream2.getFrameLength()
    );

    AudioSystem.write(appendedFiles, AudioFileFormat.Type.WAVE, new File(outputFilePath));
}