Re: Frame Capture

Ga=EBl LEQUEUX wrote:
>
> Several years ago I was confronted to this problem with a rendering =

> based PVS system. At that time my best solution was to write a memcpy =

> using movaps from AGP Memory to System mem but I'm sure there is =

> faster solutions. FRAPS for example is doing great (~30 FPS how ?).
>
> So the basic question is: "how should I transfer my render target to =

> system memory".
>

First, make sure you have a PCI-Express system and card. PCI-Express is =

much faster than AGP for read-back.

Second, make sure you benchmark the readback performance of various =

cards, as various models and various vendors have different implementations.

Third, the actual transfer method is likely to mostly be dependent on =

the system and the hardware, rather than the specific calls you're =

making. That being said, I would benchmark the difference between =

locking a render target and doing memcpy() (ideally using 64-bit reads, =

i e use doubles or better for copying), versus using =

IDirect3DDevice9::GetFrontBufferData(), versus using =

IDirect3DDevice::GetRenderTargetData().

It's also likely to be useful to double-buffer the getting -- i e, start =

render the backbuffer, and only call GetFrontBufferData() right before =

you Present() the back buffer, and similar for the other methods (which =

may require creating multiple render targets).

So, get a PCI-Express machine, get a GeForce 7950 GX and a Radeon X1900 =

(or whatever the latest and greatest is), code up the three different =

paths, and benchmark each combination. Please post back your result :-)

Cheers,

          / h+


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