C#转换AVI文件为BMP文件

AVI英文全称为Audio Video Interleaved，即音频视频交错格式。它是一种将语音和影像同步组合在一起的文件格式。AVI支持256色和RLE压缩，主要应用在多媒体光盘上，主要用来保存电视、电影等各种影像信息。

在Windows系统中，借助于API之利，我们能够轻易的实现AVI文件的分解与重组。下面，我给出一个C#版本的AVI分解示例。

using  System;
using  System.Drawing;
using  System.Runtime.InteropServices;
using  System.IO;

namespace  org.loon.util
... {
/**//// <summary>
/// org.loon.util.AVIUtil 用于AVI文件处理 
/// </summary>
 public class AVIUtil...{
                   [StructLayout(LayoutKind.Sequential, Pack = 1)]
                       struct BITMAPFILEHEADER
                   ...{
                       public ushort bfType;
                       public uint bfSize;
                       public ushort bfReserved1;
                       public ushort bfReserved2;
                       public uint bfOffBits;
                   }

                   [StructLayout(LayoutKind.Sequential, Pack = 1)]
                       struct BITMAPINFOHEADER
                   ...{
                       public uint biSize;
                       public int biWidth;
                       public int biHeight;
                       public ushort biPlanes;
                       public ushort biBitCount;
                       public uint biCompression;
                       public uint biSizeImage;
                       public int biXPelsPerMeter;
                       public int biYPelsPerMeter;
                       public uint biClrUsed;
                       public uint biClrImportant;
                       public const int BI_RGB = 0;
                   }

                   const uint DIB_RGB_COLORS = 0;

                   const uint DIB_PAL_COLORS = 1; 

            /**//// <summary>
            /// 对象转换
            /// </summary>
            /// <param name="pBITMAPINFOHEADER"></param>
            /// <returns></returns>
                   public static Bitmap ToBitmap(IntPtr pBITMAPINFOHEADER)
                   ...{
                       unsafe
                       ...{
                           BITMAPINFOHEADER* pbmi = (BITMAPINFOHEADER*)pBITMAPINFOHEADER;
                           BITMAPFILEHEADER pbmfi;
                           pbmfi.bfType = (int)'M' << 8 | (int)'B';
                           pbmfi.bfOffBits = (uint)(sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER));
                           pbmfi.bfSize = pbmfi.bfOffBits + pbmi->biSizeImage;

                           MemoryStream stream = new MemoryStream();
                           BinaryWriter bw = new BinaryWriter(stream);
                           byte[] data = new byte[sizeof(BITMAPFILEHEADER)];
                           Marshal.Copy((IntPtr)(&pbmfi), data, 0, data.Length);
                           bw.Write(data);

                           data = new byte[sizeof(BITMAPINFOHEADER)];
                           Marshal.Copy(pBITMAPINFOHEADER, data, 0, data.Length);
                           bw.Write(data);

                           data = new byte[pbmi->biSizeImage];
                           ++pbmi;
                           Marshal.Copy((IntPtr)pbmi, data, 0, data.Length);
                           bw.Write(data);
                           bw.Flush();
                           bw.BaseStream.Position = 0;

                           return new Bitmap(bw.BaseStream);
                       }
                   }
               }

        /**//// <summary>
        /// AviFile,用于AVI文件处理
        /// </summary>
        public class AviFile : IDisposable
        ...{
            const string AVIFILE32 = "AVIFIL32";
            const int AVIGETFRAMEF_BESTDISPLAYFMT = 1;

            internal enum OpenFileFlags : uint
            ...{
                OF_READ = 0x00000000,
                OF_WRITE = 0x00000001,
                OF_READWRITE = 0x00000002,
                OF_SHARE_COMPAT = 0x00000000,
                OF_SHARE_EXCLUSIVE = 0x00000010,
                OF_SHARE_DENY_WRITE = 0x00000020,
                OF_SHARE_DENY_READ = 0x00000030,
                OF_SHARE_DENY_NONE = 0x00000040,
                OF_PARSE = 0x00000100,
                OF_DELETE = 0x00000200,
                OF_VERIFY = 0x00000400,
                OF_CANCEL = 0x00000800,
                OF_CREATE = 0x00001000,
                OF_PROMPT = 0x00002000,
                OF_EXIST = 0x00004000,
                OF_REOPEN = 0x00008000,
            }


            [DllImport(AVIFILE32)]
            extern internal static void AVIFileInit();

            [DllImport(AVIFILE32)]
            extern internal static void AVIFileExit();

            [DllImport(AVIFILE32)]
            extern internal static uint AVIFileOpen(out IntPtr ppfile, string szFile, OpenFileFlags mode, IntPtr pclsidHandler);

            [DllImport(AVIFILE32)]
            extern internal static int AVIFileRelease(IntPtr pfile);

            [DllImport(AVIFILE32)]
            extern internal static uint AVIFileGetStream(IntPtr pfile, out IntPtr ppavi, uint fccType, int lParam);

            [DllImport(AVIFILE32)]
            extern internal static int AVIStreamRelease(IntPtr pavi);

            [DllImport(AVIFILE32)]
            extern internal static IntPtr AVIStreamGetFrameOpen(IntPtr pavi, int lpbiWanted);

            [DllImport(AVIFILE32)]
            extern internal static IntPtr AVIStreamGetFrame(IntPtr pgf, int lPos);

            [DllImport(AVIFILE32)]
            extern internal static int AVIStreamLength(IntPtr pavi);

            [DllImport(AVIFILE32)]
            extern internal static uint AVIStreamGetFrameClose(IntPtr pget);


            static uint mmioFOURCC(char c0, char c1, char c2, char c3)
            ...{
                return (uint)c3 << 24 | (uint)c2 << 16 | (uint)c1 << 8 | (uint)c0;
            }

            static readonly uint streamtypeVIDEO = mmioFOURCC('v', 'i', 'd', 's');
            static readonly uint streamtypeAUDIO = mmioFOURCC('a', 'u', 'd', 's');
            static readonly uint streamtypeMIDI = mmioFOURCC('m', 'i', 'd', 's');
            static readonly uint streamtypeTEXT = mmioFOURCC('t', 'x', 't', 's');

            IntPtr aviFile = IntPtr.Zero;
            IntPtr aviStream = IntPtr.Zero;
            bool disposed = false;

            public static void Initialize()
            ...{
                AVIFileInit();
            }

            public static void Terminate()
            ...{
                AVIFileExit();
            }

            public AviFile(string filename)
            ...{
                uint result;
                result = AVIFileOpen(out aviFile, filename, OpenFileFlags.OF_READ, IntPtr.Zero);
                if (result != 0)
                ...{
                    Release();
                    throw new Exception("AVIFileOpen failure.");
                }

                result = AVIFileGetStream(aviFile, out aviStream, streamtypeVIDEO, 0);
                if (result != 0)
                ...{
                    Release();
                    throw new Exception("AVIFileGetStream failure.");
                }
            }

            ~AviFile()
            ...{
                Dispose(false);
            }

            void Release()
            ...{
                if (aviStream != IntPtr.Zero)
                ...{
                    AVIStreamRelease(aviStream);
                    aviStream = IntPtr.Zero;
                }

                if (aviFile != IntPtr.Zero)
                ...{
                    AVIFileRelease(aviFile);
                    aviFile = IntPtr.Zero;
                }
            }

            public int GetMaxFrameCount()
            ...{
                if (aviStream == IntPtr.Zero)
                    throw new InvalidOperationException();
                return AVIStreamLength(aviStream);
            }

            public Bitmap GetFrame(int no)
            ...{
                if (aviStream == IntPtr.Zero)
                    throw new InvalidOperationException();

                IntPtr frame = IntPtr.Zero;
                try
                ...{
                    frame = AVIStreamGetFrameOpen(aviStream, AVIGETFRAMEF_BESTDISPLAYFMT);
                    IntPtr pbmi = AVIStreamGetFrame(frame, no);
                    return org.loon.util.AVIUtil.ToBitmap(pbmi);

                }
                finally
                ...{
                    if (frame != IntPtr.Zero)
                        AVIStreamGetFrameClose(frame);
                }
            }

            protected void Dispose(bool disposing)
            ...{
                if (disposed)
                    return;
                disposed = true;
                Release();
            }

            public void Dispose()
            ...{
                //不让垃圾回收器终止指定对象(即不将指定对象调入终止序列中)
                GC.SuppressFinalize(this);
                Dispose(true);
            }

        }
    
}

分解AVI:

                string  filename  =   " d:/test.avi " ;
                                 // 初始化
                org.loon.util.AviFile.Initialize();

                 using  (org.loon.util.AviFile avi  =   new  org.loon.util.AviFile(filename))
                 ... {
                    int max = avi.GetMaxFrameCount();
                    for (int i = 0; i < max; ++i)
                    ...{
                        Bitmap bmp = avi.GetFrame(i);
                        bmp.Save("d:/test/"+i + ".bmp");
                        bmp.Dispose();
                    }
                }
                                 // 完成
                org.loon.util.AviFile.Terminate();