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POCorrect parameters for MFCopyImage?
 

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  1. POCorrect parameters for MFCopyImage?
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    <p>I'm trying to create an IMFSample from a CImage so that I that I can encode a video from a series of images using a SinkWriter. Microsoft has a sample of how to do this with a DWORD array (instead of a CIMage) here: <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/ff819477(v=vs.85).aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/windows/desktop/ff819477(v=vs.85).aspx</a> . Doing this involves using <code>MFCopyImage()</code>, but I am getting an ACCESS VIOLATION when calling this function, so I may be passing in the wrong parameters. I am new to C++.</p> <p>Working from their sample, this is what I've got:</p> <pre><code>CImage *img = LoadImage(); IMFSample *pSample = NULL; IMFMediaBuffer *pBuffer = NULL; const LONG cbWidth = img-&gt;GetBPP() / 8 * img-&gt;GetWidth(); const DWORD cbBuffer = cbWidth * img-&gt;GetHeight(); BYTE *pData = NULL; HRESULT hr = MFCreateMemoryBuffer(cbBuffer, &amp;pBuffer); if (SUCCEEDED(hr)) { hr = pBuffer-&gt;Lock(&amp;pData, NULL, NULL); } if (SUCCEEDED(hr)) { hr = MFCopyImage( pData, cbWidth, (BYTE*)img-&gt;GetBits(), cbWidth, cbWidth, img-&gt;GetHeight() ); // ACCESS VIOLATION HERE! } if (pBuffer) { pBuffer-&gt;Unlock(); } </code></pre> <p>Anyone know why this gets me an ACCESS VIOLATION ? Am I passing in the right values, especially for the stride? Based on this documentation: <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/bb970554(v=vs.85).aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/windows/desktop/bb970554(v=vs.85).aspx</a> , it was not clear to me what exactly this parameter is supposed to be.</p> <p>Update Dec 11: Changed code sample with corrections provided by @cha and @roman-r. Still getting the same error.</p>
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    1. COHave you checked that the image is loaded OK after you call CImage *img = LoadImage()?
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    2. COI can see a small problem. GetBPP() returns number of bits per pixel. Both MFCopyImage and MFCreateMemoryBuffer use bytes. So, my guess is that you need to initialise cbWidth like this: const LONG cbWidth = img->GetBPP() / 8 * img->GetWidth();
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    3. COI think the image has loaded OK, because if I call .Save(_T("foo.jpg")) on it, I can see that the resulting image is good.
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