On Wed, 26 Sep 2001, Tom Goetze wrote: > > >It was never set up to that time. It must be set from the outside world of > >the driver. The frame buffer (*this* frame buffer) is located in your > >graphics card. > > Rolf, > > So, if I do NOT have a graphics card (just a capture card--the DC10plus) > do I have any chance of being able to capture video from my capture card? > Sure. You don't need a video card to capture into system memory. > Can I just malloc some memory and use it? No. Most capture cards (like ones using the zoran or bt848 chip) operate by DMAing the video data across the PCI bus into memory somewhere. They need a memory buffer in physical ram that won't move around or get swapped out, and often need a contiguous buffer as well. If you allocate memory in a userspace program, these requirements aren't satisfied. So instead the memory is allocated by the kernel driver. You tell the driver what kind of buffer you want somehow, and it gives you a pointer to the memory it allocated. In theory, you could allocate a buffer yourself in userspace, and then tell the driver about it and the driver would do the necessary stuff to lock it down and maybe even "defragment" it. But Linux doesn't support this.
