subject_62208.htm

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序号：62208 发表者：nbm 发表日期：2003-11-25 12:16:01
<br>主题：奇怪，我抓的图为什么上面有三分之一是黑的？
<br>内容：我抓的图上面有三分之一是黑的，所以抓的图就少了三分之一，不知道为什么？程序如下：<BR>抓图部分：<BR>&nbsp;&nbsp;&nbsp;&nbsp;HRESULT hr;<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;m_pGB-&gt;QueryInterface(IID_IBasicVideo, (void **)&amp;pibv);<BR>&nbsp;&nbsp;&nbsp;&nbsp;long* image = NULL; <BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;pibv-&gt;GetVideoSize(&amp;lWidth, &amp;lHeight); <BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;// determine size <BR>&nbsp;&nbsp;&nbsp;&nbsp;pibv-&gt;GetCurrentImage(&amp;size,image); <BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;buffer = new char[size]; <BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;hr = pibv-&gt;GetCurrentImage(&amp;size,(long*)buffer); <BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;lpbi = (LPBITMAPINFOHEADER)buffer; <BR>写文件部分：<BR>&nbsp;&nbsp;&nbsp;&nbsp;HANDLE&nbsp;&nbsp;fh;<BR>&nbsp;&nbsp;//创建位图文件&nbsp;&nbsp;&nbsp;&nbsp;<BR>&nbsp;&nbsp;&nbsp;&nbsp;fh = CreateFile(&#34;h:\\b.bmp&#34;, GENERIC_WRITE, <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0, NULL, CREATE_ALWAYS,<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);<BR><BR>&nbsp;&nbsp; if (fh == INVALID_HANDLE_VALUE)<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AfxMessageBox(&#34;error&#34;);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return ;<BR>&nbsp;&nbsp;&nbsp;&nbsp;}<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;DWORD dwWritten;<BR>&nbsp;&nbsp; // 写入位图文件头<BR>&nbsp;&nbsp; WriteFile(fh, lpbi, sizeof(BITMAPFILEHEADER), &amp;dwWritten, NULL);<BR><BR>&nbsp;&nbsp; // 写入位图文件其余内容<BR>&nbsp;&nbsp; WriteFile(fh, (LPSTR)buffer, size,&nbsp;&nbsp;&amp;dwWritten, NULL);<BR>&nbsp;&nbsp; <BR>&nbsp;&nbsp; //消除内存分配&nbsp;&nbsp;<BR>&nbsp;&nbsp; CloseHandle(fh);<BR>
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<font color=red>答案被接受</font><br>回复者：DickieX 回复日期：2003-11-25 17:22:43
<br>内容：BITMAPFILEHEADER里面的值要设定吧.
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回复者：nbm 回复日期：2003-11-25 17:35:27
<br>内容：谢谢，我的问题已经解决了，你知不知道如何从某一帧开始播放，并能把该帧取出来存成BMP?<BR>
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回复者：donly 回复日期：2003-11-26 23:31:46
<br>内容： IMediaSeek接口有：可以设置播放的位置！<BR>hr = m_pMS-&gt;SetPositions(&amp;pos, AM_SEEKING_AbsolutePositioning ,<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; NULL, AM_SEEKING_NoPositioning);<BR><BR>其实Directshow的IMediaDet里面已经提供了保存BMP的方法，直接用该函数就可以了<BR>hr=m_pMD-&gt;WriteBitmapBits(dCurTime,m_lWidth,m_lHeight,wsFilename);<BR>&nbsp;&nbsp;&nbsp;&nbsp;if (FAILED(hr))&nbsp;&nbsp;return FALSE;<BR><BR>查看一下帮助什么都有^_^
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