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// MovieGrabberDLL.cpp : 定义 DLL 应用程序的入口点。// #include "stdafx.h"#include "MovieGrabberDLL.h"BOOL APIENTRY DllMain( HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved )
...{
switch (ul_reason_for_call)
...{ case DLL_PROCESS_ATTACH: case DLL_THREAD_ATTACH: case DLL_THREAD_DETACH: case DLL_PROCESS_DETACH: break;
} return TRUE;
} /**//*** 抓取视频的截图* @param aPath 视频文件的位置* @return*/MOVIEGRABBERDLL_API HANDLE GrabMovieFrame(LPCTSTR aPath,int grayColorCountThreshold)...{ HRESULT hr; // 定义IMediaDet接口实例 CComPtr< IMediaDet > pDet; hr = pDet.CoCreateInstance(__uuidof(MediaDet)); if (FAILED(hr)) return NULL; // 将影片文件名转换成BSTR类型 CComBSTR openBSTR(aPath); // 设置IMediaDet接口的文件关联 hr = pDet->put_Filename(openBSTR); if (FAILED(hr)) return NULL; // 从影片中检索视频流和音频流 long lStreams; hr = pDet->get_OutputStreams(&lStreams); if (FAILED(hr)) return NULL; // 取出影片的视频流，因为帧的信息是保存在视频流中的 bool bFound = false; for (int i=0; i<lStreams; i++) ...{ GUID major_type; hr = pDet->put_CurrentStream(i); if (SUCCEEDED(hr)) hr = pDet->get_StreamType(&major_type); if (FAILED(hr)) break; if (major_type == MEDIATYPE_Video) ...{ bFound = true; break; } } if (!bFound) return NULL; long width = 0, height = 0; // 存储位图的宽和高（单位：象素） AM_MEDIA_TYPE mt; hr = pDet->get_StreamMediaType(&mt); if (SUCCEEDED(hr)) ...{ if ((mt.formattype == FORMAT_VideoInfo) && (mt.cbFormat >= sizeof(VIDEOINFOHEADER))) ...{ // 得到VIDEOINFOHEADER结构指针，VIDEOINFOHEADER结构包含一些与视频 // 有关的信息，其中含有BITMAPINFORHEADER结构 VIDEOINFOHEADER *pVih = (VIDEOINFOHEADER*)(mt.pbFormat); width = pVih->bmiHeader.biWidth; height = pVih->bmiHeader.biHeight; if(height < 0 ) height *= -1; } else hr = VFW_E_INVALIDMEDIATYPE; MyFreeMediaType(mt); // 释放AM_MEDIA_TYPE结构 } if (FAILED(hr)) return NULL; return (HANDLE)LookforSuitableMovieFrame(pDet,width,height,grayColorCountThreshold);} /**//*** 写入合适视频帧截图到磁盘* @param pDet DirectShow的IMediaDet接口* @param width 截图的长* @param height 截图的宽* @param grayColorCountThreshold 灰度颜色个数阈值*/HBITMAP LookforSuitableMovieFrame(IMediaDet* pDet,int width,int height,int grayColorCountThreshold)...{ long size; double time = 0.0; double totaltime; // 获取整个视频的时间长度 pDet->get_StreamLength(&totaltime); // 每1秒,截取视频截图 for(time=0.0; time <totaltime; time+= 1.0) ...{ // 获取bitmap的buffer大小 HRESULT hr = pDet->GetBitmapBits(time, &size, 0, width, height); if (SUCCEEDED(hr)) ...{ char *pBuffer = new char[size]; if (!pBuffer) return NULL; hr = pDet->GetBitmapBits(time, 0, pBuffer, width, height); if (SUCCEEDED(hr)) ...{ // Find the address of the start of the image data. void *pData = pBuffer + sizeof(BITMAPINFOHEADER); if(IsSuitableMovieFrame(pData,width,height,grayColorCountThreshold)) ...{ BITMAPINFOHEADER *bmih = (BITMAPINFOHEADER*)pBuffer; HDC hdcDest = GetDC(0); BITMAPINFO bmi; ZeroMemory(&bmi, sizeof(BITMAPINFO)); CopyMemory(&(bmi.bmiHeader), bmih, sizeof(BITMAPINFOHEADER)); HBITMAP hBitmap = CreateDIBitmap(hdcDest, bmih, CBM_INIT, pData, &bmi, DIB_RGB_COLORS); delete[] pBuffer; return hBitmap; } } delete[] pBuffer; } } return NULL;} /**//*** 检测一个位图是否是合适的视频截图* @param pData 位图的点色数组* @param width 位图的长* @param height 位图的宽* @param grayColorCountThreshold 灰度颜色个数阈值*/bool IsSuitableMovieFrame(void* pData,int width,int height,int grayColorCountThreshold)...{ BYTE* pixels = (BYTE*)pData; int numGrayColor = 0; int size = width*height; int graycolor; int i,j; int* appearedcolors = new int[grayColorCountThreshold]; int numappearedcolors = 0; for(i=0;i<size; i++) ...{ // 计算当前点的灰度值，采用的RGB转换灰度的公式是GRAY = (R+G+B)/3 graycolor = (pixels[i*3] +pixels[i*3+1]+pixels[i*3+2])/3; // 检测该灰度色是否之前出现过 for(j=0;j<numappearedcolors; j++) ...{ if(graycolor == appearedcolors[j]) break; } if(j == numappearedcolors) // 如果是新的灰度颜色值 ...{ numappearedcolors++; if(numappearedcolors == grayColorCountThreshold) // 如果灰度颜色个数满足阈值 ...{ delete[] appearedcolors; return true; // 返回信息，合适 } else ...{ appearedcolors[j] = graycolor; // 记录下该灰度颜色值 } } } delete[] appearedcolors; return false; // 返回信息，不合适} void MyFreeMediaType(AM_MEDIA_TYPE& mt)...{ if(mt.cbFormat != 0) ...{ CoTaskMemFree((PVOID)mt.pbFormat); mt.cbFormat = 0; } if (mt.pUnk != NULL) ...{ mt.pUnk->Release(); mt.pUnk = NULL; }}如果您非常迫切的想了解IT领域最新产品与技术信息，那么订阅至顶网技术邮件将是您的最佳途径之一。
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