Java:从音频文件中提取字节

Question

从音频文件中提取数据字节时,以下两种实现有什么区别？

该文件是一个.wav文件,我想只提取数据,没有标题或任何其他东西.

实施1:

public byte[] extractAudioFromFile(String filePath) {
    try {
        // Get an input stream on the byte array
        // containing the data
        File file = new File(filePath);
        final AudioInputStream audioInputStream = AudioSystem
                .getAudioInputStream(file);

        byte[] buffer = new byte[4096];
        int counter;
        while ((counter = audioInputStream.read(buffer, 0, buffer.length)) != -1) {
            if (counter > 0) {
                byteOut.write(buffer, 0, counter);
            }
        }
        audioInputStream.close();
        byteOut.close();
    } catch (Exception e) {
        System.out.println(e);
        System.exit(0);
    }// end catch

    return ((ByteArrayOutputStream) byteOut).toByteArray();
}

实施2:

public byte[] readAudioFileData(String filePath) throws IOException,
        UnsupportedAudioFileException {
    final AudioInputStream audioInputStream = AudioSystem
            .getAudioInputStream(new File(filePath));
    AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, byteOut);
    audioInputStream.close();
    byteOut.close();

    return ((ByteArrayOutputStream) byteOut).toByteArray();
}

每个实现都返回不同大小的字节.第一个返回byte[]的长度小于第二个实现.

我试图提取数据字节以显示文件的频谱图.

任何解释都赞赏.

谢谢,

萨默尔

Answer 1

第二个impl正在编写完整的WAVE'文件格式'.第二个缓冲区比第一个缓冲区大44个字节吗？

[编辑:好奇到实际尝试它 - 以上是正确的]

package so_6933920;

import java.io.ByteArrayOutputStream;
import java.io.File;

import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;

public class AudioFiles {
    public static void main(String[] args) {
        String file = "clarinet.wav";
        AudioFiles afiles = new AudioFiles();
        byte[] data1 = afiles.readAudioFileData(file);
        byte[] data2 = afiles.readWAVAudioFileData(file);
        System.out.format("data len: %d\n", data1.length);
        System.out.format("data len: %d\n", data2.length);
        System.out.format("diff len: %d\n", data2.length - data1.length);
    }
    public byte[] readAudioFileData(final String filePath) {
        byte[] data = null;
        try {
            final ByteArrayOutputStream baout = new ByteArrayOutputStream();
            final File file = new File(filePath);
            final AudioInputStream audioInputStream = AudioSystem
            .getAudioInputStream(file);

            byte[] buffer = new byte[4096];
            int c;
            while ((c = audioInputStream.read(buffer, 0, buffer.length)) != -1) {
                baout.write(buffer, 0, c);
            }
            audioInputStream.close();
            baout.close();
            data = baout.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return data;
    }
    public byte[] readWAVAudioFileData(final String filePath){
        byte[] data = null;
        try {
            final ByteArrayOutputStream baout = new ByteArrayOutputStream();
            final AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(new File(filePath));

            AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, baout);
            audioInputStream.close();
            baout.close();
            data = baout.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return data;
    }
}

我用这个示例WAV文件尝试了这个.

结果:

data len: 489708
data len: 489752
diff len: 44

注意:我对你的代码片段采取了一些自由来清理它.

1. 这System.exit(0)是一个明确的禁忌.
2. if(counter > 0)实际上并不是必需的,因为counter必须大于0read方法的返回值-1.