On Mon, Oct 08, 2001 at 03:54:14PM -0700, Sottek, Matthew J wrote: > The drm _does_ allow the client to mmap the video ram. I am not completely sure about this, but as I'm also working on the same thing as Vladimir, capturing for ATI AIWs, I think he is talking about mmap-ing DMA buffers, not the videoram directly.
> > Basically I want to DMA a chunk of video ram into plain RAM. This
> >is useful for: video capture, VBI/closed captioning, taking screen
> >snapshots.
> I think you are going about this the wrong way.
No he isn't.
> Video capture does not need to get video ram into system ram.
If it is a combo card such as AIW, you indeed need to do that. When you
instruct the capture board to provide the data, it will appear in videoram.
> ram via Xv. (NOT: capture card -> video ram->dma back to system ram)
This indeed is how AIW cards work.
Back to volodya: I already asked the same question as you about 2 times
withing last 6 weeks and the result seems to be that neither DRM nor X have an
interface of doing captures. I'm currently working on a new Xv function
(XvShmGetImage) that will do this, and also when I see some code from your
radeon captures I'll adapt it to r128 and create a new DRM function as well,
but first I want to have a non-dma function so that I can test it if it really
works and worry about the speed later. Yes I know memcpy from videoram is slow
as hell.
I imagine that, similarly to r128's new XvPutImage, XvGetImage will try the
DRM function and if it fails or isn't implemented, falls back to memcpy.
I think this is the right way to do it: think about a new DRM function that is
somewhat similar to BlitTexture but the opposite way, implement it on ATI's
and send a patch.
The code inside DMAXvGetImage will look like this:
drmDMA (blahblah); // allocate buffers
for (buffer = 0; buffer < buffer_size; buffer ++;) {
drmNewUberCoolCapturingFunction;
memcpy (shm segment for capturing + buffersize*buffer, drm buffer, buffersize);
}
drmFree (blahblah);
Has anyone a better idea?
Bye,
Peter Surda (Shurdeek) <[EMAIL PROTECTED]>, ICQ 10236103, +436505122023
--
To boldly go where I surely don't belong.
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