文件数量较多的情况下如何提高刻录速度（调用IMAPI2实现DVD刻录功能）

在调用IMAPI2实现DVD刻录功能时，如果文件数量较多时，刻录占用的时间也较长，因此考虑先将刻录文件制作成ISO files，然后再刻录到DVD中。以此来优化刻录功能。

调用IMAPI2的方法在www.codeproject.com 有例子可以参考，网址为http://www.codeproject.com/KB/winsdk/IMAPI2.aspx 。在此就不再班门弄斧，下面讲讲Creating ISO files的方法。

1.  创建镜像文件

using System.Runtime.InteropServices;

using System.Runtime.InteropServices.ComTypes;

using IMAPI2.Interop;

//Import this legacy Win32API...

[DllImport("shlwapi.dll", CharSet = CharSet.Unicode)] static internal extern uint SHCreateStreamOnFile (string pszFile, uint grfMode, out IStream ppstm);

//Create

IFileSystemImage ifsi = new MsftFileSystemImage();
ifsi.ChooseImageDefaultsForMediaType(IMAPI_MEDIA_PHYSICAL_TYPE.IMAPI_MEDIA_TYPE_DISK);
ifsi.FileSystemsToCreate =
    FsiFileSystems.FsiFileSystemJoliet | FsiFileSystems.FsiFileSystemISO9660;
ifsi.VolumeName = "YourVolume";
ifsi.Root.AddTree("c:\\YourDirToArchive", true);//use a valid folder
//this will implement the Write method for the formatter
IStream imagestream = ifsi.CreateResultImage().ImageStream;
if (imagestream != null)
{
    System.Runtime.InteropServices.ComTypes.STATSTG stat;
    imagestream.Stat(out stat, 0x01);
    IStream newStream;
    if (0 == SHCreateStreamOnFile
        ("C:\\YourImage.iso", 0x00001001, out newStream) && newStream != null)
    {
        IntPtr inBytes = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(long)));
        IntPtr outBytes = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(long)));
        try
        {
            imagestream.CopyTo(newStream, stat.cbSize, inBytes, outBytes);
            Marshal.ReleaseComObject(imagestream);
            imagestream = null;
            newStream.Commit(0);
        }
        finally
        {
            Marshal.ReleaseComObject(newStream);
            Marshal.FreeHGlobal(inBytes);
            Marshal.FreeHGlobal(outBytes);
            if (imagestream != null)
                Marshal.ReleaseComObject(imagestream);
        }
    }
}
Marshal.ReleaseComObject(ifsi);

2.  增加单独的文件到镜像中

使用IFsiDirectoryItem记录文件的原始路径，使用Update事件跟踪进程。

private void CreateFSIFile(FileInfo file, IFsiDirectoryItem diritem)
{
    string realpath = UniqueListFileSystemInfo.GetPhysicalPath(file.FullName);
    int index = realpath.IndexOf(":\\") + 1;
    if (_sysImage.Exists(realpath.Substring(index)) == FsiItemType.FsiItemNotFound)
    {
        IFsiDirectoryItem crtdiritem = diritem as IFsiDirectoryItem;
        string name = Path.GetFileName(realpath);
        if (string.Compare(diritem.FullPath,
            Path.GetDirectoryName(realpath).Substring(index), true) != 0)
        {
            string fsipath = Path.GetDirectoryName(realpath).Substring
            (index + 1 + diritem.FullPath.Length);
            string[] dirs = fsipath.Split('\\');

            //create the subdirs one by one
            foreach (string dir in dirs)
            {
                if (dir.Length == 0)
                    continue;//in the root like C:\
                try
                {
                    string newpath = string.Format("{0}\\{1}", crtdiritem.FullPath, dir);
                    if (_sysImage.Exists(newpath) != FsiItemType.FsiItemDirectory)
                        crtdiritem.AddDirectory(dir);
                }
                catch
                {
                    Cancel = true;
                    throw;
                }
                crtdiritem = crtdiritem[dir] as IFsiDirectoryItem;
            }
        }

        System.Runtime.InteropServices.ComTypes.IStream newStream = null;

        try
        {
            newStream = LoadCOMStream(realpath);
            crtdiritem.AddFile(name, newStream);
        }
        finally
        {
            Marshal.ReleaseComObject(newStream);
        }

        _actualSize += ((FileInfo)file).Length;
        if (Update != null && Update.GetInvocationList().Length > 0)
            Update(file.FullName, ((FileInfo)file).Length);
    }
    else
        throw new IOException("invalid file or folder");
}

参考文章：http://www.codeproject.com/KB/miscctrl/ISOImage.aspx?msg=2464574

更多的ISO制作的功能请参考How to Create Optical File Images using IMAPIv2.0 和 How to Burn Optical File Images with IMAPI 2.0 from Managed Code