[directshow - directdraw - c++]how to retrieve primary directdraw surface?
Author
hi
I am using the IDirectDrawVideo interface of the Video Renderer Filter. Thanks to GetDirectDraw method I can retrieve the DIRECTDRAW object (the video renderer filter is connected to a source).
Then to retrieve the primary directdraw I used IDirectDrawVideo::GetSurfaceDesc that should give me surface descriptor which has lpSurface pointer to the DirectDraw surface but the pointer is NULL.
So I tried to retrieve IDirectDrawVideo after paused the graph ( as it said in doc : "Surfaces are allocated only when the renderer is paused") then the surfaceType is equals to AMDDS_YUVFLP and dwWidth and dwHeight of the surfaceDesc are correct : 320 * 240 (and that is the size of my capture source)
But lpSurface is still NULL. What's wrong?
thx
Author
arf I cant understand why the size is correct and the lpSurface pointer is still null
I'm just getting into DirectShow too, so this would be a good learning experience for me as well.
From the looks of IDirectDrawVideo::GetSurfaceDesc(), it needs the address of a structure to be filled. You said that "the pointer is NULL" which makes me wonder if you're passing in a pointer of type DDSURFACEDESC instead of passing the address of a DDSURFACEDESC structure like you should. If that's not the case, are you making sure to set the dwSize member of the structure before you pass it in?
Beyond that, I don't know what the error could be without seeing some code first. However, I recommend that you look through the DirectShow sample files to see how they set up code to do something similar to what you want.
From the looks of IDirectDrawVideo::GetSurfaceDesc(), it needs the address of a structure to be filled. You said that "the pointer is NULL" which makes me wonder if you're passing in a pointer of type DDSURFACEDESC instead of passing the address of a DDSURFACEDESC structure like you should. If that's not the case, are you making sure to set the dwSize member of the structure before you pass it in?
Beyond that, I don't know what the error could be without seeing some code first. However, I recommend that you look through the DirectShow sample files to see how they set up code to do something similar to what you want.
Author
first thx for helping me.
I am so confused, i did not see in documentation: "dwSize: Size of the structure. Must be initialized prior to use."
So I tried to initialized it :
Then I print properties's with cout, and i got :
surfaceDesc.dwSize: 108 (dot not know if it is correct)
surfaceDesc.dwWidth: 320 (good, correct)
surfaceDesc.dwHeight: 240 (good, correct)
surfaceDesc.dwBackBufferCount: 0 (dot not know if it is correct)
surfaceDesc.dwFlags: 4111 (dot not know if it is correct)
surfaceDesc.lpSurface: NULL (BAD, why still NULL ?)
any idea ? what could I try ?
thx
I am so confused, i did not see in documentation: "dwSize: Size of the structure. Must be initialized prior to use."
So I tried to initialized it :
DDSURFACEDESC surfaceDesc ;surfaceDesc.dwSize = sizeof(DDSURFACEDESC) ;IDirectDrawVideo* m_pdd ;m_pdd->GetSurfaceDesc(&surfaceDesc) ;Then I print properties's with cout, and i got :
surfaceDesc.dwSize: 108 (dot not know if it is correct)
surfaceDesc.dwWidth: 320 (good, correct)
surfaceDesc.dwHeight: 240 (good, correct)
surfaceDesc.dwBackBufferCount: 0 (dot not know if it is correct)
surfaceDesc.dwFlags: 4111 (dot not know if it is correct)
surfaceDesc.lpSurface: NULL (BAD, why still NULL ?)
any idea ? what could I try ?
thx
Hmm... I'm not really sure. Here's what the DirectX documentation says about GetSurfaceDesc()
Quote:Return ValuesCheck the HRESULT of the function to see if it's failing.
Returns an HRESULT value. If no surface has been allocated, this method will return E_FAIL. If a DCI primary surface is in use, the DDSURFACEDESC structure will not be filled in and the call will return S_FALSE.
Remarks
Surfaces are allocated only when the renderer is paused. After the renderer has been paused, it cannot release the surfaces when stopped.
Author
yeah sure I already checked and all result are equals to S_OK, but I did not write "hr =" and "if (FAILED(hr))" in this forum because it takes a lot of lines. And you right about pause the graph, but I did not write into this forum for same reasons.
--------------------------
...
IBaseFilter *m_pVideoRenderer;
CoCreateInstance(CLSID_VideoRenderer, 0, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&m_pVideoRenderer);
m_pVideoRenderer->QueryInterface(IID_IDirectDrawVideo, (LPVOID *) &m_pdd);
...
m_g_pGraph->QueryInterface(IID_IMediaControl,(LPVOID *) &m_g_pMC);
...
m_g_pMC->Run() ;
...
...
...
m_g_pMC->Pause() ;
DDSURFACEDESC surfaceDesc ;
ZeroMemory(&surfaceDesc, sizeof(surfaceDesc));
surfaceDesc.dwSize = sizeof(surfaceDesc);
IDirectDrawVideo* m_pdd ;
m_pdd->GetSurfaceDesc(&surfaceDesc) ;
--------------------------
-> all result are OK
then after printing, there is:
surfaceDesc.dwSize: 108
surfaceDesc.dwWidth: 320
surfaceDesc.dwHeight: 240
surfaceDesc.dwBackBufferCount: 0
surfaceDesc.dwFlags: 4111
surfaceDesc.lpSurface: NULL
An other idea ?
[Edited by - CaptainL on September 10, 2007 6:44:26 AM]
--------------------------
...
IBaseFilter *m_pVideoRenderer;
CoCreateInstance(CLSID_VideoRenderer, 0, CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&m_pVideoRenderer);
m_pVideoRenderer->QueryInterface(IID_IDirectDrawVideo, (LPVOID *) &m_pdd);
...
m_g_pGraph->QueryInterface(IID_IMediaControl,(LPVOID *) &m_g_pMC);
...
m_g_pMC->Run() ;
...
...
...
m_g_pMC->Pause() ;
DDSURFACEDESC surfaceDesc ;
ZeroMemory(&surfaceDesc, sizeof(surfaceDesc));
surfaceDesc.dwSize = sizeof(surfaceDesc);
IDirectDrawVideo* m_pdd ;
m_pdd->GetSurfaceDesc(&surfaceDesc) ;
--------------------------
-> all result are OK
then after printing, there is:
surfaceDesc.dwSize: 108
surfaceDesc.dwWidth: 320
surfaceDesc.dwHeight: 240
surfaceDesc.dwBackBufferCount: 0
surfaceDesc.dwFlags: 4111
surfaceDesc.lpSurface: NULL
An other idea ?
[Edited by - CaptainL on September 10, 2007 6:44:26 AM]
Author
Did someone already test it ? ( to retrieve primary directdraw surface from Video Renderer Filter )
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