How to read MP3 file tags

问题:

I want to have a program that reads metadata from an MP3 file. My program should also able to edit these metadata. What can I do?

I got to search out for some open source code. But they have code; but not simplified idea for my job they are going to do.

When I read further I found the metadata is stored in the MP3 file itself. But I am yet not able to make a full idea of my baby program.

Any help will be appreciated; with a program or very idea (like an algorithm). :)

回答1:

The last 128 bytes of a mp3 file contains meta data about the mp3 file., You can write a program to read the last 128 bytes...

UPDATE:

ID3v1 Implementation

The Information is stored in the last 128 bytes of an MP3. The Tag has got the following fields, and the offsets given here, are from 0-127.

 Field      Length    Offsets
 Tag        3           0-2
 Songname   30          3-32
 Artist     30         33-62
 Album      30         63-92
 Year       4          93-96
 Comment    30         97-126
 Genre      1           127

WARINING- This is just an ugly way of getting metadata and it might not actually be there because the world has moved to id3v2. id3v1 is actually obsolete. Id3v2 is more complex than this, so ideally you should use existing libraries to read id3v2 data from mp3s . Just putting this out there.

回答2:

You can use apache tika Java API for meta-data parsing from MP3 such as title, album, genre, duraion, composer, artist and etc.. required jars are tika-parsers-1.4, tika-core-1.4.

Sample Program:

package com.parse.mp3;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import org.apache.tika.exception.TikaException;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.Parser;
import org.apache.tika.parser.mp3.Mp3Parser;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class AudioParser {

    /**
     * @param args
     */
    public static void main(String[] args) {
        String fileLocation = "G:/asas/album/song.mp3";

        try {

        InputStream input = new FileInputStream(new File(fileLocation));
        ContentHandler handler = new DefaultHandler();
        Metadata metadata = new Metadata();
        Parser parser = new Mp3Parser();
        ParseContext parseCtx = new ParseContext();
        parser.parse(input, handler, metadata, parseCtx);
        input.close();

        // List all metadata
        String[] metadataNames = metadata.names();

        for(String name : metadataNames){
        System.out.println(name + ": " + metadata.get(name));
        }

        // Retrieve the necessary info from metadata
        // Names - title, xmpDM:artist etc. - mentioned below may differ based
        System.out.println("----------------------------------------------");
        System.out.println("Title: " + metadata.get("title"));
        System.out.println("Artists: " + metadata.get("xmpDM:artist"));
        System.out.println("Composer : "+metadata.get("xmpDM:composer"));
        System.out.println("Genre : "+metadata.get("xmpDM:genre"));
        System.out.println("Album : "+metadata.get("xmpDM:album"));

        } catch (FileNotFoundException e) {
        e.printStackTrace();
        } catch (IOException e) {
        e.printStackTrace();
        } catch (SAXException e) {
        e.printStackTrace();
        } catch (TikaException e) {
        e.printStackTrace();
        }
        }
    }

回答3:

For J2ME(which is what I was struggling with), here's the code that worked for me..

import java.io.InputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.file.FileConnection;
import javax.microedition.lcdui.*;
import javax.microedition.media.Manager;
import javax.microedition.media.Player;
import javax.microedition.media.control.MetaDataControl;
import javax.microedition.midlet.MIDlet;

public class MetaDataControlMIDlet extends MIDlet implements CommandListener {
  private Display display = null;
  private List list = new List("Message", List.IMPLICIT);
  private Command exitCommand = new Command("Exit", Command.EXIT, 1);
  private Alert alert = new Alert("Message");
  private Player player = null;  

  public MetaDataControlMIDlet() {    
    display = Display.getDisplay(this);
    alert.addCommand(exitCommand);
    alert.setCommandListener(this);
    list.addCommand(exitCommand);
    list.setCommandListener(this);
    //display.setCurrent(list);

  }

  public void startApp() {
      try {
      FileConnection connection = (FileConnection) Connector.open("file:///e:/breathe.mp3");
      InputStream is = null;
      is = connection.openInputStream();
      player = Manager.createPlayer(is, "audio/mp3");
      player.prefetch();
      player.realize();
    } catch (Exception e) {
      alert.setString(e.getMessage());
      display.setCurrent(alert);
      e.printStackTrace();
    }

    if (player != null) {
      MetaDataControl mControl = (MetaDataControl) player.getControl("javax.microedition.media.control.MetaDataControl");
      if (mControl == null) {
        alert.setString("No Meta Information");
        display.setCurrent(alert);
      } else {
        String[] keys = mControl.getKeys();
        for (int i = 0; i < keys.length; i++) {
          list.append(keys[i] + " -- " + mControl.getKeyValue(keys[i]), null);
        }
        display.setCurrent(list);
      }
    }
  }

  public void commandAction(Command cmd, Displayable disp) {
    if (cmd == exitCommand) {
      notifyDestroyed();
    }
  }

  public void pauseApp() {
  }

  public void destroyApp(boolean unconditional) {
  }

}