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Fastest method to update video to texture


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#1   Members   

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Posted 15 November 2012 - 09:38 PM

I have a need to upload video frames to a texture and I have seen two different methods to do this. What I would like to know is which is the fastest method.

Method #1
- hr = m_pDevice->CreateTexture(m_width, m_height, 0, D3DUSAGE_DYNAMIC, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &m_pTexture, NULL);
- hr = m_pTexture->LockRect(0, &d3dlr, NULL, D3DLOCK_DISCARD);
- Write to d3dlr.pBits;
- m_pTexture->UnlockRect(0);

Method #2
- hr = pDevice->CreateTexture(m_width, m_height, 0, D3DUSAGE_DYNAMIC, D3DFMT_A8R8G8B8, D3DPOOL_SYSTEMMEM, &m_memTexture,NULL);
- hr = pDevice->CreateTexture(m_width, m_height, 0, D3DUSAGE_RENDERTARGET, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &m_texture,NULL);
- hr = m_memTexture->LockRect(0, &d3dRect, NULL, D3DLOCK_DISCARD | D3DLOCK_DONOTWAIT);
- Write to d3dlr.pBits;
- hr = m_memTexture->UnlockRect(0);
- hr = pDevice->UpdateTexture(m_memTexture, m_texture);

Edited by Headkaze, 15 November 2012 - 09:41 PM.


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Posted 16 November 2012 - 12:10 AM

The difference between the two is that the first one directly locks the texture in GPU texture memory and writes there, whereas the second one creates a temporary texture in system memory, writes there, uploads it to the GPU and performs the copy GPU-side. I'm pretty sure both approaches use DMA ultimately to push the new texture to the GPU (in the first method, the transfer would occur upon UnlockRect, and in the second one, at UpdateTexture), so I don't think it'd make a difference. The first one might be a bit faster, but drivers are pretty smart nowadays.

But you should try and benchmark it just to be sure.

Edited by Bacterius, 16 November 2012 - 12:11 AM.

“If I understand the standard right it is legal and safe to do this but the resulting value could be anything.”


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Posted 16 November 2012 - 11:07 AM

Is this D3D9? I don't remember a LockRect() in D3D11.

Edited by KingofNoobs, 16 November 2012 - 11:08 AM.

I wonder as I wander...

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Posted 16 November 2012 - 06:22 PM

But you should try and benchmark it just to be sure.


I agree. Has anyone else performed any benchmarks using these two methods?

Is this D3D9? I don't remember a LockRect() in D3D11.


Yes, as you can see I tagged my post with D3D9

Edited by Headkaze, 16 November 2012 - 06:24 PM.





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