C#将图像存成视频

http://www.codeproject.com/Articles/7388/A-Simple-C-Wrapper-for-the-AviFile-Library

文章摘至上面这个网页，进行了一点点的翻译

Introduction

This is an article for everyone who does not want to spend hours messing around with the AVIFile functions, if he only wants to read or change a simple AVI video. I have wrapped the most important AVIFile functions into three easy to use C# classes that can handle the following tasks:

• Read images from the video stream.
• Decompress a compressed video stream.
• Compressan uncompressed video stream.
• Change the compression of a video stream.
• Export the video stream into a separate.avi file.
• Export the audio stream into a.wav file.
• Copy a couple of seconds from audio and video stream into a new.avi file.
• Add sound from a .wav file to the video.
• Create a new video stream from a list of bitmaps.
• Add frames to an existing video stream, compressed or not.
• Insert frames into a stream.
• Copy or delete frames from a stream.

These features cover the common use cases like creating a video from a couple of images and a wave sound, extracting the sound track from a video, cutting out short clips, or grabbing a single picture from a movie.

This article has got two sections:

• First, I'll explain the demo application so that you can use it to explore the library on your own.
• Then, I'll explain how the library works step by step.

How to use the library - A walk through the demo application

The Explore tab

The Explore tab lets you explore an AVI file, and offers simple tasks that don't need editable streams:

At the top of the form, you can choose the AVI file you want to explore.text.avi from the test data folder is pre-selected. On the left side, you can display header information about the video and the wave sound stream (if available). Also, you can see image frames from the video in a PictureBox:

The images are read by a VideoStream object. GetFrameOpen prepares the stream for decompressing frames, GetFrameClose releases the resources used to decompress the frame, and GetBitmap decompresses a frame and converts it to a System.Drawing.Bitmap.

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AviManager aviManager = new AviManager(txtAviFileName.Text, true);

VideoStream aviStream = aviManager.GetVideoStream();//获得视频流

aviStream.GetFrameOpen();//是数据流准备接受解压的图片帧

picFrame.Image =

  aviStream.GetBitmap(Convert.ToInt32(numPosition.Value));//将图片解压

aviStream.GetFrameClose();//释放接受解压图片的数据流

aviManager.Close();

In the middle of the demo form, you can work with whole streams:

解压

Decompress removes the compression from a video stream. It creates a new file and video stream, decompresses each frame from the old stream, and writes it into the new stream. The result is a large new .avi file with the same video but no compression.

压缩

Compress changes the compression of the video, or applies compression to an uncompressed video. It does the same asUncompress, but compresses the new stream. These two functions use the same method CopyFile:

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private void CopyFile(String newName, bool compress){

    //open compressed file  打开压缩文件

    AviManager aviManager =

        new AviManager(txtAviFileName.Text, true);准备

    VideoStream aviStream = aviManager.GetVideoStream();准备视频流

    //create un-/re-compressed file

    AviManager newManager =

        aviStream.DecompressToNewFile(newName, compress); 将压缩文件解压

 

    //close compressed file  关闭解压文件

    aviManager.Close();

    //save and close un-/re-compressed file

    newManager.Close();

}

Whenever an instance of VideoStream creates a compressed stream, it asks you for a codec and settings:每当创建一个压缩的流，必须询问压缩软件和相关设置

将视频文件分解成很多位图

Extract Bitmaps splits the video into many separate bitmap files:

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VideoStream stream = aviManager.GetVideoStream();

stream.GetFrameOpen();  //数据流准备接受帧图片

 

String path = @"..\..\testdata\";       //将每一帧图片存储入视频流

for(int n=0; n<stream.CountFrames; n++){

stream.ExportBitmap(n, path+n.ToString()+".bmp");

//下面可以用三句话代替

}

 

stream.GetFrameClose();

Of course, you can save the images in any format.（图片可以存储成任何格式）ExportBitmap is just a shortcut for these three lines:

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Bitmap bmp = stream.GetBitmap(position);

bmp.Save(FileName);

bmp.Dispose();

Extract Video copies the whole video stream into a new AVI file. You can use it to get rid of all the other streams like MIDI, text and Wave sound.在混合视频流中提取单纯的视频

The lower box deals with Wave sound.Extract Sound copies the whole sound stream into a Wave file. This is not a big task, it requires only four lines of code: 混合视频流中提取音频数据

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AviManager aviManager =

    new AviManager(txtAviFileName.Text, true);

AudioStream audioStream = aviManager.GetWaveStream();

audioStream.ExportStream( @"..\..\testdata\sound.wav" );

aviManager.Close();

Extract a few Seconds lets you copy video and sound between second X and second Y. First, a CopyForm dialog lets you enter X and Y, then these parts are cut out of the video and sound streams://在一个混合流中取得

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AviManager aviManager = new AviManager(txtAviFileName.Text, true);

VideoStream aviStream = aviManager.GetVideoStream();

CopyForm dialog = new CopyForm(0,

  aviStream.CountFrames / aviStream.FrameRate);

if (dialog.ShowDialog() == DialogResult.OK) {

  int startSecond = dialog.Start;

  int stopSecond = dialog.Stop;

 

  AviManager newFile = aviManager.CopyTo(

    "..\\..\\testdata\\video.avi", startSecond, stopSecond);

  newFile.Close();

}

aviManager.Close();

给视频添加音频

Add Sound lets you choose a.wav file, and adds it to the video. You can use this feature to add a sound track to a silent video, for example, re-add the sound to a video extracted withExtract Video. Adding sound is a simple task of three lines:

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String fileName = GetFileName("Sounds (*.wav)|*.wav");

if(fileName != null){

    AviManager aviManager =

        new AviManager(txtAviFileName.Text, true);

    aviManager.AddAudioStream(fileName);

    aviManager.Close();

}

The last set of functions is about creating new video streams. Enter a list of image files in the box and animate them:

从多个图片组合保存成视频并经过压缩保存

Create uncompressed builds a new video from the images, and saves it without any compression.Create and Compress does the same, except that it displays the compression settings dialog and compresses the images. Both methods create a new file, and pass a sample bitmap to AddVideoStream. The sample bitmap is used to set the format of the new stream. Then, all the images from the list are added to the video.

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//load the first image

Bitmap bitmap = (Bitmap)Image.FromFile(txtFileNames.Lines[0]);//加载第一幅图片

//create a new AVI file 建一个avi文件

AviManager aviManager =

    new AviManager(@"..\..\testdata\new.avi", false);

//add a new video stream and one frame to the new file 将新的视频流和一帧图像存入视频

VideoStream aviStream =

    aviManager.AddVideoStream(true, 2, bitmap);

 

Bitmap bitmap;

int count = 0;

for(int n=1; n<txtFileNames.Lines.Length; n++){//一个循环，将图片加入视频

    if(txtFileNames.Lines[n].Trim().Length > 0){

        bitmap =

           (Bitmap)Bitmap.FromFile(txtFileNames.Lines[n]);

        aviStream.AddFrame(bitmap);

        bitmap.Dispose();

        count++;

    }

}

aviManager.Close();

//将一个相片添加到一个视频流（需要区分压缩和非压缩两种情况）

Add Frames appends the images to the existing video stream. To an uncompressed video stream, we could append frames by simply opening the stream and adding frames as usual. But a compressed stream cannot be re-compressed. AVIStreamWrite - used by AddFrame - would not return any error; but anyway, it would add the new frames uncompressed and produce nothing but strangely colored pixel storms. To add frames to a compressed stream, the existing frames must be decompressed and added to a new compressed stream. Then the additional frames can be added to that stream:

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//open file

Bitmap bmp = (Bitmap)Image.FromFile(txtFileNames.Lines[0]);

AviManager aviManager =

    new AviManager(txtAviFileName.Text, true);

VideoStream aviStream = aviManager.GetVideoStream();

 

//streams cannot be edited - copy to a new file

AviManager newManager = aviStream.DecompressToNewFile(

                        @"..\..\testdata\temp.avi", true);

aviStream = newManager.GetOpenStream(0);

 

//add images

Bitmap bitmap;

for(int n=0; n<txtFileNames.Lines.Length; n++){

    if(txtFileNames.Lines[n].Trim().Length > 0){

        bitmap =

            (Bitmap)Bitmap.FromFile(txtFileNames.Lines[n]);

        aviStream.AddFrame(bitmap);

        bitmap.Dispose();

    }

}

 

aviManager.Close(); //close old file

newManager.Close(); //save and close new file

 

//delete old file, replace with new file

System.IO.File.Delete(txtAviFileName.Text);

System.IO.File.Move(@"..\..\testdata\temp.avi",

                            txtAviFileName.Text);

上面就是这个函数提供的功能

Now that you know how to use the AVIFile wrapper classes, let's have a look at the background.

编辑视频流

The Edit tab

The Edit tab demonstrates tasks for editable AVI streams, like pasting frames at any position in the stream, or changing the frame rate://编辑选项

When you have chosen a file to edit, an editable stream is created from the video stream, and the editor buttons become enabled. A normal video stream is locked; for inserting and deleting frames, you need an editable stream:

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AviManager file = new AviManager(fileName, true);

VideoStream stream = file.GetVideoStream();

EditableVideoStream editableStream =

           new EditableVideoStream(stream);

file.Close();

On the left side, you can copy or cut frame sequences, and paste them at another position in the same stream:

Copying frames from one stream, and pasting them into another or the same stream, is only two lines of code:

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//copy frames

IntPtr copiedData = editableStream.Copy(start, length);

 

//insert frames

editableStream.Paste(copiedData, 0, position, length);

There is no other method for deleting frames than just cut and forget them:

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//cut and paste frames

IntPtr copiedData = editableStream.Cut(start, length);

editableStream.Paste(copiedData, 0, position, length);

 

//delete frames == cut without paste

IntPtr deletedData = editableStream.Cut(start, length);

In the middle of the dialog, you can insert frames from image files anywhere in the stream, and change the frame rate to make the video play back slower or faster:

We can paste only streams, not bitmaps, so the bitmaps from the list are written into a temporary AVI file and then pasted as a stream:

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//create temporary video file

String tempFileName = System.IO.Path.GetTempFileName() + ".avi";

AviManager tempFile = new AviManager(tempFileName, false);

 

//write the new frames into the temporary video stream

Bitmap bitmap =

  (Bitmap)Image.FromFile(txtNewFrameFileName.Lines[0].Trim());

tempFile.AddVideoStream(false, 1, bitmap);

VideoStream stream = tempFile.GetVideoStream();

 

for (int n=1; n<txtNewFrameFileName.Lines.Length; n++) {

   if (txtNewFrameFileName.Lines[n].Trim().Length > 0) {

       stream.AddFrame(

         (Bitmap)Image.FromFile(txtNewFrameFileName.Lines[n]));

   }

}

 

//paste the video into the editable stream

editableStream.Paste(stream, 0,

   (int)numPastePositionBitmap.Value, stream.CountFrames);

Do you find your video too slow, or too fast? Tell the player application to play more/less frames per second:

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Avi.AVISTREAMINFO info = editableStream.StreamInfo;

info.dwRate = (int)(numFrameRate.Value * 10000);

info.dwScale = 10000;

editableStream.SetInfo(info);

The last box is not for editing, it is only a preview player. You should preview your editable stream before saving it to an AVI file.

预览窗口的实现

A preview player is easy to implement, you only need a PictureBox and the video stream you want to play. A label displaying the current frame index can be helpful, too. A start button, a stop button, and there you are:

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private void btnPlay_Click(object sender, EventArgs e) {

    player = new AviPlayer(editableStream,

                pictureboxPreview, labelFrameIndex);

    player.Stopped += new System.EventHandler(player_Stopped);

    player.Start();

    SetPreviewButtonsState();

}

 

private void player_Stopped(object sender, EventArgs e) {

        btnPlay.Invoke(

           new SimpleDelegate(SetPreviewButtonsState));

}

 

private void SetPreviewButtonsState() {

        btnPlay.Enabled = ! player.IsRunning;

        btnStop.Enabled = player.IsRunning;

}

 

private void btnStop_Click(object sender, EventArgs e) {

        player.Stop();

}

How it works

AviManger manages the streams in an AVI file. The constructor takes the name of the file and opens it. Close closes all opened streams and the file itself. You can add new streams with AddVideoStream and AddAudioStream. New video streams are empty, Wave streams can only be created from Wave files. After you have created an empty video stream, use the methods of VideoStream to fill it. But what actually happens when you add a stream?

//创建一个视频流

Create a video stream

There are two methods for creating a new video stream: create from a sample bitmap, or create from explicit format information. Both methods do the same, they pass their parameter on to VideoStream and add the new stream to the internal list of opened streams, to close them before closing the file:

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public VideoStream AddVideoStream(

    bool isCompressed, //display the compression dialog,

     // create a compressed stream

    int frameRate, //frames per second

    int frameSize, //size of one frame in bytes

    int width, int height, PixelFormat format //format of

                                              //the bitmaps

    ){

 

    VideoStream stream = new VideoStream(

        aviFile,

        isCompressed,

        frameRate,

        frameSize,

        width, height, format);

 

    streams.Add(stream);

    return stream;

}

 

public VideoStream AddVideoStream(

    bool isCompressed, //display the compression dialog,

      // create a compressed stream

    int frameRate, //frames per second

    Bitmap firstFrame //get the format from this image

      // and add it to the new stream

    ){

 

    VideoStream stream = new VideoStream(

        aviFile,

        isCompressed,

        frameRate,

        firstFrame);

 

    streams.Add(stream);

    return stream;

}

利用格式化信息来创建一个视频数据流，然后如果···就压缩这个视频

Then, VideoStream uses the format data to create a new stream. It calls AVIFileCreateStream and, if writeCompressed says so, AVIMakeCompressedStream:

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public VideoStream(

    int aviFile, //pointer to the file object

    bool writeCompressed, //true: create compressed stream

    int frameRate, //frames per second

    ...

    ){

 

    //store format information

    //...

 

    //create the stream

    CreateStream();

}

 

private void CreateStream(){

    //fill stream information

    Avi.AVISTREAMINFO strhdr = new Avi.AVISTREAMINFO();

    strhdr.fccType = Avi.mmioStringToFOURCC("vids", 0);

    strhdr.fccHandler = Avi.mmioStringToFOURCC("CVID", 0);

    strhdr.dwScale = 1;

    strhdr.dwRate = frameRate;

    strhdr.dwSuggestedBufferSize = frameSize;

    strhdr.dwQuality = -1; //default

    strhdr.rcFrame.bottom = (uint)height;

    strhdr.rcFrame.right = (uint)width;

    strhdr.szName = new UInt16[64];

//创建视频流

    //create the stream

    int result = Avi.AVIFileCreateStream(aviFile,

                          out aviStream, ref strhdr);

 

    if(writeCompressed){

        //create a compressed stream from

        //the uncompressed stream

        CreateCompressedStream();

    }

}

//压缩视频流

private void CreateCompressedStream(){

    Avi.AVICOMPRESSOPTIONS_CLASS options =

             new Avi.AVICOMPRESSOPTIONS_CLASS();

    options.fccType = (uint)Avi.streamtypeVIDEO;

    options.lpParms = IntPtr.Zero;

    options.lpFormat = IntPtr.Zero;

 

    //display the compression options dialog

    Avi.AVISaveOptions(

      IntPtr.Zero,

      Avi.ICMF_CHOOSE_KEYFRAME | Avi.ICMF_CHOOSE_DATARATE,

      1, ref aviStream, ref options);

//得到压缩视频流

    //get a compressed stream

    Avi.AVICOMPRESSOPTIONS structOptions =

                            options.ToStruct();

    int result = Avi.AVIMakeCompressedStream(

        out compressedStream,

        aviStream,

        ref structOptions, 0);

 

    //format the compressed stream

    SetFormat(compressedStream);

}

//用类而不是结构体更加容易处理指针相关的问题

AVICOMPRESSOPTIONS_CLASS is the AVICOMPRESSOPTIONS structure as a class. Using classes instead of structures is the easiest way to deal with pointers to pointers. If you don't know what I'm talking about, you probably have never used AVISaveOptions or AVISaveV in .NET. Take a look at the original declaration:

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BOOL AVISaveOptions(

  HWND hwnd,

  UINT uiFlags,

  int nStreams,

  PAVISTREAM * ppavi,

  LPAVICOMPRESSOPTIONS * plpOptions

);

//在C#中结构体是按值传递的，如果用引用来传递一个结构体，那么一个指向这个结构体的指针就被传递，类的实例在传递给函数作为参数的时候，总是作为一个指针传递的，如果一个类参数是用引用，那么写个的相关声明应该写成;

LPAVICOMPRESSOPTIONS is a pointer to a pointer to an AVICOMPRESSOPTIONS structure. In C#, structures are passed by value. If you pass a structure by ref, a pointer to the structure is passed. Instances of classes are always passed to methods as pointers. So a class-parameter by ref means a pointer to a pointer to the object. The C# declarations of AVISaveOptions and AVICOMPRESSOPTIONS are:

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[DllImport("avifil32.dll")]

public static extern bool AVISaveOptions(

    IntPtr hwnd,

    UInt32 uiFlags,

    Int32 nStreams,

    ref IntPtr ppavi,

    ref AVICOMPRESSOPTIONS_CLASS plpOptions

    );

 

[StructLayout(LayoutKind.Sequential, Pack=1)]

    public struct AVICOMPRESSOPTIONS {

    public UInt32   fccType;

    public UInt32   fccHandler;

    public UInt32   dwKeyFrameEvery;

    public UInt32   dwQuality;

    public UInt32   dwBytesPerSecond;

    public UInt32   dwFlags;

    public IntPtr   lpFormat;

    public UInt32   cbFormat;

    public IntPtr   lpParms;

    public UInt32   cbParms;

    public UInt32   dwInterleaveEvery;

}

 

[StructLayout(LayoutKind.Sequential, Pack=1)]

public class AVICOMPRESSOPTIONS_CLASS {

    public UInt32   fccType;

    public UInt32   fccHandler;

    public UInt32   dwKeyFrameEvery;

    public UInt32   dwQuality;

    public UInt32   dwBytesPerSecond;

    public UInt32   dwFlags;

    public IntPtr   lpFormat;

    public UInt32   cbFormat;

    public IntPtr   lpParms;

    public UInt32   cbParms;

    public UInt32   dwInterleaveEvery;

 

    public AVICOMPRESSOPTIONS ToStruct(){

        AVICOMPRESSOPTIONS returnVar = new AVICOMPRESSOPTIONS();

        returnVar.fccType = this.fccType;

        returnVar.fccHandler = this.fccHandler;

        returnVar.dwKeyFrameEvery = this.dwKeyFrameEvery;

        returnVar.dwQuality = this.dwQuality;

        returnVar.dwBytesPerSecond = this.dwBytesPerSecond;

        returnVar.dwFlags = this.dwFlags;

        returnVar.lpFormat = this.lpFormat;

        returnVar.cbFormat = this.cbFormat;

        returnVar.lpParms = this.lpParms;

        returnVar.cbParms = this.cbParms;

        returnVar.dwInterleaveEvery = this.dwInterleaveEvery;

        return returnVar;

    }

}

//在新的视频流中添加帧数据

With this workaround, we are able to call AVISaveOptions and (later on) AVISaveV in C#. Now, the new stream can be filled with image frames using AddFrame: 

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public void AddFrame(Bitmap bmp){

    bmp.RotateFlip(RotateFlipType.RotateNoneFlipY);

 

    if (countFrames == 0){

       //  the format of the first frame defines the format of the stream

       CopyPalette(bmp.Palette);

       SetFormat(writeCompressed ? compressedStream : aviStream,

                 countFrames);

    }

//锁定内存

    //lock the memory block

    BitmapData bmpDat = bmp.LockBits(

        new Rectangle(

        0,0, bmp.Width, bmp.Height),

        ImageLockMode.ReadOnly, bmp.PixelFormat);

//向视频流添加数据

    //add the bitmap to the (un-)compressed stream

    int result = Avi.AVIStreamWrite(

        writeCompressed ? compressedStream : aviStream,

        countFrames, 1,

        bmpDat.Scan0,

        (Int32)(bmpDat.Stride * bmpDat.Height),

        0, 0, 0);

//解锁内存

    //unlock the memory block

    bmp.UnlockBits(bmpDat);

//计算帧的数目

    //count the frames, so that we don't have to

    //call AVIStreamLength for every new frame

    countFrames++;

} 

 

//我们也可以将帧直接添加到已有的视频中 

Now, we are able to fill an empty stream with images. But what can we do to add frames to an existing stream? Well, first, we have to open the stream with the third constructor.

Re-compress a video stream

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public VideoStream(int aviFile, IntPtr aviStream){

 

    this.aviFile = aviFile;

    this.aviStream = aviStream;

 

    //read the stream's format

    Avi.BITMAPINFOHEADER bih = new Avi.BITMAPINFOHEADER();

    int size = Marshal.SizeOf(bih);

    Avi.AVIStreamReadFormat(aviStream, 0, ref bih, ref size);

    Avi.AVISTREAMINFO streamInfo = GetStreamInfo(aviStream);

 

    //store the important format values

    this.frameRate = streamInfo.dwRate / streamInfo.dwScale;

    this.width = (int)streamInfo.rcFrame.right;

    this.height = (int)streamInfo.rcFrame.bottom;

    this.frameSize = bih.biSizeImage;

    this.countBitsPerPixel = bih.biBitCount;

 

    //get the count of frames that are already there

    int firstFrame = Avi.AVIStreamStart(aviStream.ToInt32());

    countFrames =

       firstFrame + Avi.AVIStreamLength(aviStream.ToInt32());

}

//如果视频没有压缩，那么就可以使用conpress，不然的话，先必须解压现有的帧，然后将所有帧压缩到一个新的流中

If you are sure the video stream is not compressed, you can call AddFrame now. Otherwise, you have to decompress the existing frames, and recompress them into a new stream:

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public AviManager DecompressToNewFile(String fileName,

                                        bool recompress){

    //create a new AVI file

    AviManager newFile = new AviManager(fileName, false);

 

    //create a video stream in the new file

    this.GetFrameOpen();

    Bitmap frame = GetBitmap(0);

    VideoStream newStream =

        newFile.AddVideoStream(recompress, frameRate, frame);

 

    //decompress each frame and add it to the new stream

    for(int n=1; n<countFrames; n++){

        frame = GetBitmap(n);

        newStream.AddFrame(frame);

    }

 

    this.GetFrameClose();

 

    return newFile;

}

 

DecompressToNewFile creates a writeable copy of the stream in a new file. You can add frames to this new stream, close the new AviManager to save it, and then add the sound stream from the old file to complete the copy. Adding frames to a video is not easy, but this way it works.

//分离数据流

Separate a stream

Sometimes, you might have a video file with sound, but you only need the silent video, or only the sound. It is not necessary to copy each frame, you can open the stream as usual and export it with AVISaveV. This works with all kinds of streams, only the compression options are different:

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public override void ExportStream(String fileName){

    Avi.AVICOMPRESSOPTIONS_CLASS opts =

                new Avi.AVICOMPRESSOPTIONS_CLASS();

 

    //for video streams

    opts.fccType = (UInt32)Avi.mmioStringToFOURCC("vids", 0);

    opts.fccHandler = (UInt32)Avi.mmioStringToFOURCC("CVID", 0);

 

    //for audio streams

    //opts.fccType = (UInt32)Avi.mmioStringToFOURCC("auds", 0);

    //opts.fccHandler = (UInt32)Avi.mmioStringToFOURCC("CAUD", 0);

 

    //export the stream

    Avi.AVISaveV(fileName, 0, 0, 1, ref aviStream, ref opts);

}

//将一个波形文件输入进来

Import sound from a Wave file

Now, we are able to build a video from bitmaps, and extract sound from it. And how does the sound get into the file? We could use AVISaveV again, to combine the video and audio streams in a new file - but we don't have to. The easiest way to add a new audio stream is to open the Wave file as an AVI file with only one stream, and then copy that stream:

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public void AddAudioStream(String waveFileName){

    //open the wave file

    AviManager audioManager =

        new AviManager(waveFileName, true);

    //get the wave sound as an audio stream...

    AudioStream newStream = audioManager.GetWaveStream();

    //...and add it to the file

    AddAudioStream(newStream);

    audioManager.Close();

}

 

public void AddAudioStream(AudioStream newStream){

    Avi.AVISTREAMINFO streamInfo = new Avi.AVISTREAMINFO();

    Avi.PCMWAVEFORMAT streamFormat = new Avi.PCMWAVEFORMAT();

    int streamLength = 0;

 

    //read header info, format and length,

    //and get a pointer to the wave data

    IntPtr waveData = newStream.GetStreamData(

        ref streamInfo,

        ref streamFormat,

        ref streamLength);

 

    //create new stream

    IntPtr aviStream;

    Avi.AVIFileCreateStream(aviFile, out aviStream,

                                      ref streamInfo);

 

    //add format new stream

    Avi.AVIStreamSetFormat(

        aviStream, 0,

        ref streamFormat,

        Marshal.SizeOf(streamFormat));

 

    //copy the raw wave data into the new stream

    Avi.AVIStreamWrite(

        aviStream, 0,

        streamLength,

        waveData,

        streamLength,

        Avi.AVIIF_KEYFRAME, 0, 0);

 

    Avi.AVIStreamRelease(aviStream);

}

Copy a clip from video and sound

I have added this method, because many people asked me how this could be done. To copy a part of the video stream from second X to second Y, the indices of the first and last frames have to be calculated from the frame rate and second. For the Wave stream, we must calculate the byte offsets from samples per second, bits per sample, and the requested seconds. The rest is onlycopy and paste:

Collapse | Copy Code

public AviManager CopyTo(String newFileName,

    int startAtSecond, int stopAtSecond) {

    AviManager newFile = new AviManager(newFileName, false);

 

    try {

        //copy video stream

 

        VideoStream videoStream = GetVideoStream();

 

        int startFrameIndex =

             videoStream.FrameRate * startAtSecond;

        int stopFrameIndex =

             videoStream.FrameRate * stopAtSecond;

 

        videoStream.GetFrameOpen();

        Bitmap bmp = videoStream.GetBitmap(startFrameIndex);

 

        VideoStream newStream = newFile.AddVideoStream(

             false,

             videoStream.FrameRate,

             bmp);

 

        for (int n = startFrameIndex + 1;

                     n <= stopFrameIndex; n++) {

            bmp = videoStream.GetBitmap(n);

            newStream.AddFrame(bmp);

        }

        videoStream.GetFrameClose();

 

        //copy audio stream

 

        AudioStream waveStream = GetWaveStream();

 

        Avi.AVISTREAMINFO streamInfo =

                         new Avi.AVISTREAMINFO();

        Avi.PCMWAVEFORMAT streamFormat =

                         new Avi.PCMWAVEFORMAT();

        int streamLength = 0;

        IntPtr ptrRawData = waveStream.GetStreamData(

            ref streamInfo,

            ref streamFormat,

            ref streamLength);

 

        int startByteIndex = waveStream.CountSamplesPerSecond

               * startAtSecond

               * waveStream.CountBitsPerSample / 8;

 

        int stopByteIndex = waveStream.CountSamplesPerSecond

               * stopAtSecond

               * waveStream.CountBitsPerSample / 8;

 

        ptrRawData =

          new IntPtr(ptrRawData.ToInt32() + startByteIndex);

 

        byte[] rawData =

          new byte[stopByteIndex - startByteIndex];

        Marshal.Copy(ptrRawData, rawData, 0, rawData.Length);

 

        streamInfo.dwLength = rawData.Length;

        streamInfo.dwStart = 0;

 

        IntPtr unmanagedRawData =

              Marshal.AllocHGlobal(rawData.Length);

        Marshal.Copy(rawData, 0, unmanagedRawData,

                                     rawData.Length);

 

        newFile.AddAudioStream(unmanagedRawData,

              streamInfo,

              streamFormat,

              rawData.Length);

 

    } catch (Exception ex) {

        newFile.Close();

        throw ex;

    }

 

    return newFile;

}

If you are still interested in AVI videos, download the wrapper library and the demo application. Finally, I dare to say: have fun with AVIFile!

Known issues

Adding frames to an existing stream does not work with all video codecs and/or bitmaps. You might get a StackOverflowException or broken frames. If you find out why this happens, please let me know.

History

• 9^th July, 2004 - updated downloads.
• 3^rd October, 2004 - new method AviManager.CopyTo.
• 18^th December, 2004 - new classes EditableVideoStream and AviPlayer, and a few memory leaks fixed.
• 26^th November, 2005 - removed performance reducers from VideoStream.GetBitmap.
• 01^st January, 2006 - Corrections for invalid colour depth and interlaced video in VideoStream.GetFrameOpen, new property VideoStream.FirstFrame. Thanks a lot to Michael Covington!

License

This article, along with any associated source code and files, is licensed underThe Code Project Open License (CPOL)

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