最近在做一个视频识别项目，需要用到视频处理，在codeproject上找到了一个关于对Avi的操作库，感觉不错，在这里把一些要点记录下来
http://www.codeproject.com/Articles/7388/A-Simple-C-Wrapper-for-the-AviFile-Library
Avi视频文件的编码有很多，这个库只支持部分Avi文件，有些Avi文件不支持，具体哪些不支持还没搞清楚
AviFile库提供了
1、从视频流中图片的处理
2、视频中音频的处理
3、压缩和解压视频流
1、使用
1、从视频读取图片，还有一些参数可以通过aviStream查看到，可以把当前流信息输出到文件
//Avi文件读取
string filepath = @"D: est.avi";
AviManager aviManager = new AviManager(filepath, true);
VideoStream aviStream = aviManager.GetVideoStream();
//获取和保存音频流到文件
AudioStream audioStream = aviManager.GetWaveStream();
audioStream.ExportStream(@"D: est.wav");
aviStream.GetFrameOpen();
//获取视频总帧数
int framecount = aviStream.CountFrames;
//获取第5帧的图片
Bitmap bmp = aviStream.GetBitmap(5);
//视频速度
double rate = aviStream.FrameRate;
//直接保存帧图片到文件
//aviStream.ExportBitmap(5, @"D:frame_05.jpg");
//保存当前流到文件
//aviStream.ExportStream(@"D:currenttest.avi")
aviStream.GetFrameClose();
aviManager.Close();
2、把图片和音频写入视频流（部分参数后面会说到，这里只是简单的演示）
//读取图片文件
string[] files = Directory.GetFiles(@"D: est", "*.jpg");
AviManager aviManager = new AviManager(@"D:
ewtest.avi", false);
//添加音频
String fileName = @"D:audio.wav";
aviManager.AddAudioStream(fileName, 0);
//读取第一张图片，设置每秒3帧
VideoStream aviStream = aviManager.AddVideoStream(true, 3, new Bitmap(files[0]));
for (int i = 1; i < files.Length; i++)
{
aviStream.AddFrame(new Bitmap(files[i]));
}
aviManager.Close();
3、从视频截取一段保存到AviManager
AviManager aviManager = new AviManager(filepath, true);
float startSecond = 0;
float stopSecond = 10;
//截取0-10s放到newManager
AviManager newManager = aviManager.CopyTo(@"D:
ewtest_0-10.avi", startSecond, stopSecond);
4、对已压缩的视频进行解压缩，放到另一个VideoStream中
VideoStream newstream;
AviManager newManager = aviStream.DecompressToNewFile(@"D: 1.avi", false, out newstream);
newstream.GetFrameOpen();
Bitmap bitmap = newstream.GetBitmap(10);
newstream.GetFrameClose();
5、向视频流中添加一张图片帧，对于未压缩的视频流，我们可以直接进行添加，但是对于已经压缩过的视频流，添加的图片帧不能重新进行压缩，所以我们需要对其进行解压缩，操作完后在进行压缩
//读取图片文件
string[] files = Directory.GetFiles(@"D: est", "*.jpg");
//打开一个已存在的视频
AviManager aviManager = new AviManager(@"D: est.avi", true);
VideoStream avistream = aviManager.GetVideoStream();
VideoStream newstream;
//解压视频到newstream中，最后已压缩的形式保存
AviManager newManager = avistream.DecompressToNewFile(@"newtest.avi", true, out newstream);
avistream = newManager.GetOpenStream(0);
for (int i = 1; i < files.Length; i++)
{
avistream.AddFrame(new Bitmap(files[i]));
}
aviManager.Close();
//关闭和保存文件newtest.avi
newManager.Close();
6、编辑视频流 EditableVideoStream (可以对视频流的帧，进行cut，delete，paste等早错)
//打开一个已存在的视频
AviManager aviManager = new AviManager(@"D: est.avi", true);
VideoStream avistream = aviManager.GetVideoStream();
EditableVideoStream editableStream = new EditableVideoStream(avistream);
int start = 0;
int length =10;
int position = 10;
//Copy
IntPtr copiedData = editableStream.Copy(start, length);
//Insert
editableStream.Paste(copiedData, 0, position, length);
//Delete
IntPtr deletedData = editableStream.Cut(start, length);
同时也可以把一个 VideoStream 流 Paste 到 EditableVideoStream
editableStream.Paste(stream, 0, position, stream.CountFrames);
7、对视频流进行一些参数设置
Avi.AVISTREAMINFO info = editableStream.StreamInfo;
//设置播放速度：每秒 3帧
info.dwRate = 3;
editableStream.SetInfo(info);
2、AviFile后台工作
AviManager 管理Avi文件的stream，构造函数传入文件名，当调用Close函数时，关闭所有打开的流和文件，并保存。
可以使用 AddVideoStream 和 AddAudioStream 把视频里和音频流添加到一个新的AviManager中，音频流只支持wav文件
Create a video stream
VideoStream 有两个构造函数
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;
}
VideoStream使用格式化的数据创建新的流，调用 AVIFileCreateStream，如果 isCompressed参数为true，则调用 AVIMakeCompressedStream
public VideoStream(int aviFile, bool writeCompressed, int frameRate, ...)
{
//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];
//create the stream
int result = Avi.AVIFileCreateStream(aviFile, out aviStream, ref strhdr);
if(writeCompressed)
{
//create a compressed stream from
CreateCompressedStream();
}
}
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);
//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);
}
其中使用 AVICOMPRESSOPTIONS_CLASS 类代替 AVICOMPRESSOPTIONS 结构体，使用类代替结构体在使用指针的时候更加容易，如果你看不懂，你可能没在.Net使用过 AVISaveOptions 或 AVISaveV，下面看看 AVISaveOptions 的声明
BOOL AVISaveOptions(
HWND hwnd,
UINT uiFlags,
int nStreams,
PAVISTREAM * ppavi,
LPAVICOMPRESSOPTIONS * plpOptions);
LPAVICOMPRESSOPTIONS 是一个指向 AVICOMPRESSOPTIONS 结构体指针的指针（指向指针的指针）
在C#中，结构体是值传递的，如果使用ref来传递结构体，则传递的是指向结构体的指针
而类使用的是引用，实际传递的是指针，地址，所以使用ref传递类时，实际传递的是指向类指针的指针（指向指针的指针），
所以这里使用类代替结构体，下面是在C#中声明 AVISaveOptions 和 AVICOMPRESSOPTIONS
[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;
}
}
在这个工作区，可以调用 AVISaveOptions ,来设置Avi文件的一些参数
通过AddFrame函数可以用图片填充视频流
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);
}
//lock the memory block
BitmapData bmpDat = bmp.LockBits(
new Rectangle(0,0, bmp.Width, bmp.Height),
ImageLockMode.ReadOnly, bmp.PixelFormat);
//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);
//unlock the memory block
bmp.UnlockBits(bmpDat);
//count the frames, so that we don't have to call AVIStreamLength for every new frame
countFrames++;
}
Add frames to an existing stream
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());
}
如果视频流是未压缩的，可以直接调用AddFrame，否则，需要对其进行解压缩，并重新压缩到一个新的流
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 创建一个可编辑的拷贝到一个新的文件流，可以添加frames到该流
Separate a stream
有时，我们可能只想要视频的声音，或是只要没有声音的视频，我们没有必要重新创建视频，添加每一帧到视频流中，可以通过使用 AviSaveV 把当前流到处到文件，AVISaveV只是所有类型的流，只是压缩参数不一样而已
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);
}
Import sound from a Wave file
现在，我们可以通过Bitmap来生成视频，也可以从视频中导出声音，那么当我们导入wav文件的时候，底层是如何工作的呢，我们还是可以用 AVISaveV 这个方法，来组合视频和音频成一个文件，但这里我们有更简单的方法，打开音频文件作为Avi文件，然后拷贝到另一个流中
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);
}
截取视频流
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;
}