102 lines
2.8 KiB
C
102 lines
2.8 KiB
C
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// 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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