将exif数据写入android视频文件

Question

我在android中使用Id3库提取元数据信息（Exif infor），但我得到空指针异常并在日志中获取消息它是一个原因因为src_set中的值为null。我不知道为什么它是返回null。我的代码是：

    File src = new File(pathdata);
    MusicMetadataSet src_set = null;
    try {
        src_set = new MyID3().read(src);
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } // read metadata

    if (src_set == null) // perhaps no metadata
    {
        Log.i("NULL", "NULL");
    }
    else
    {
    try{
    IMusicMetadata metadata = src_set.getSimplified();
    String artist = metadata.getArtist();  
    String album = metadata.getAlbum();  
    String song_title = metadata.getSongTitle(); 
    Number track_number = metadata.getTrackNumber(); 
    Log.i("artist", artist);
    Log.i("album", album);
    }catch (Exception e) {
        e.printStackTrace();
    }
    File dst = new File(pathdata);
    MusicMetadata meta = new MusicMetadata("name");
    meta.setAlbum("Chirag");
    meta.setArtist("CS");
    try {
        new MyID3().write(src, dst, src_set, meta);
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ID3WriteException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }  // write updated metadata




}