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Open Source Computer Vision Library
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102 lines
2.8 KiB
102 lines
2.8 KiB
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF |
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// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO |
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// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A |
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// PARTICULAR PURPOSE. |
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// |
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// Copyright (c) Microsoft Corporation. All rights reserved |
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#pragma once |
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////////////////////////////////////////////////////////////////////////// |
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// VideoBufferLock |
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// |
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// Description: |
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// Locks a video buffer that might or might not support IMF2DBuffer. |
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// |
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////////////////////////////////////////////////////////////////////////// |
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class VideoBufferLock |
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{ |
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public: |
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VideoBufferLock(IMFMediaBuffer *pBuffer) : m_p2DBuffer(NULL) |
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{ |
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m_pBuffer = pBuffer; |
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m_pBuffer->AddRef(); |
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// Query for the 2-D buffer interface. OK if this fails. |
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m_pBuffer->QueryInterface(IID_PPV_ARGS(&m_p2DBuffer)); |
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} |
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~VideoBufferLock() |
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{ |
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UnlockBuffer(); |
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SafeRelease(&m_pBuffer); |
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SafeRelease(&m_p2DBuffer); |
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} |
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// LockBuffer: |
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// Locks the buffer. Returns a pointer to scan line 0 and returns the stride. |
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// The caller must provide the default stride as an input parameter, in case |
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// the buffer does not expose IMF2DBuffer. You can calculate the default stride |
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// from the media type. |
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HRESULT LockBuffer( |
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LONG lDefaultStride, // Minimum stride (with no padding). |
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DWORD dwHeightInPixels, // Height of the image, in pixels. |
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BYTE **ppbScanLine0, // Receives a pointer to the start of scan line 0. |
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LONG *plStride // Receives the actual stride. |
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) |
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{ |
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HRESULT hr = S_OK; |
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// Use the 2-D version if available. |
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if (m_p2DBuffer) |
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{ |
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hr = m_p2DBuffer->Lock2D(ppbScanLine0, plStride); |
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} |
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else |
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{ |
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// Use non-2D version. |
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BYTE *pData = NULL; |
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hr = m_pBuffer->Lock(&pData, NULL, NULL); |
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if (SUCCEEDED(hr)) |
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{ |
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*plStride = lDefaultStride; |
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if (lDefaultStride < 0) |
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{ |
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// Bottom-up orientation. Return a pointer to the start of the |
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// last row *in memory* which is the top row of the image. |
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*ppbScanLine0 = pData + abs(lDefaultStride) * (dwHeightInPixels - 1); |
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} |
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else |
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{ |
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// Top-down orientation. Return a pointer to the start of the |
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// buffer. |
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*ppbScanLine0 = pData; |
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} |
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} |
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} |
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return hr; |
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} |
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HRESULT UnlockBuffer() |
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{ |
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if (m_p2DBuffer) |
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{ |
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return m_p2DBuffer->Unlock2D(); |
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} |
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else |
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{ |
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return m_pBuffer->Unlock(); |
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} |
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} |
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private: |
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IMFMediaBuffer *m_pBuffer; |
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IMF2DBuffer *m_p2DBuffer; |
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}; |
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