Hi everyone, I’m working on a project to implement a color transformation of all pixels in the framebuffer. I’d like to add this transform at a layer where video from all sources (mesa, X, directfb) can be modified with a color transformation. I’ve researched linux driver, mesa and xserver source and based on the architecture described at: http://intellinuxgraphics.org/documentation/presentations/Graphics_architecture.pdf it looks like drm is the correct place to add my transform as it is the common layer immediately above the hardware which manages video frame buffer memory. I’d ideally like to add a transform whenever video is ready to transfer from the frame buffer to the scanout buffer and be displayed on the screen. I’m having trouble finding a set of locations where this actually occurs and I’m wondering if someone on this list can point me in the right direction. I’ve setup systemtap scripts to analyze the interactions with the drm driver and video driver. In my case I’ve started with a virtualbox system and vmwgfx, although I’d like to eventually support intel platforms. I’ve found drm_mode_dirtyfb_ioctl is one ioctl which seems to be invoked whenever the display changes (as I move the mouse across the screen, start applications, etc) however I don’t see this method when I attempt to play a video with mplayer. Based on my research I had expected video to use overlay buffers, however I also don’t see calls to overlay ioctls like vmw_overlay_ioctl, vmw_stream_*_ioctl. I see references to the scanout buffer in drm_irq and intel_display within drm source, as well as in the documentation at http://www.kernel.org/doc/htmldocs/drm/ch02s05.html but I’m having a hard time figuring out where the scanout buffer actually *is*. If I could understand the relationship between the framebuffer and scanout buffer better I could probably use this to figure out where I’d need to add my transform. I’m still trying to come up to speed with the entire video architecture and have a long way to go but I was wondering if someone on this list can provide any pointers or even just provide their opinion about whether what I’m trying to do is even possible. Any input is much appreciated. Thanks for your time. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
