On Aug 30, 2012, at 5:16 PM, Carsten Haitzler (The Rasterman) <ras...@rasterman.com> wrote:
> On Thu, 30 Aug 2012 13:40:09 -0500 Nick Reed <n...@fuel7.com> said: > >> I'm running E17 with X11 on a TI DM8148 (SGX 530) platform with OpenGL >> compositing enabled. We're using hardware acceleration available on the SOC >> to do H.264 video decode through Gstreamer, and need to render this video on >> the display along with a graphical overlay from X. We can use the hardware >> video layer (which takes care of color conversion in hardware) and a color >> key to enable transparency between the E17/X11 framebuffer and the video >> layer in the background. The graphics hardware also supports per pixel alpha >> blending between layers, which we would prefer over a simple color key. >> >> Is there a way I can convince E17 in the presence of a compositor to let me >> write alpha values to the frame buffer? Should I abandon the hardware video >> layer and move to Emotion? > > no. you can't. because x11 has no concept of a alpha mask for the fb. it > doesn't exist. it may be pure LUCK that it happens to work. most of these hw > alpha masks are non-premultiplied rgba, but allof x1's rgba space is > premultimplied (xrender, and thus all compositors too). you have no way to > find > out if such an alpha mask exists or what kind of colorspace it is. > > then you get the bonus fun - which regions of a window contain a video and > which don't? which do you blend onto a window below and which do you treat as > conceptually solud but the regions alpha pixels are to be "copied to the > fb" (and assuming which rgba alpha colorspace?). again - doesn't exist in x11. > all you have in x11 is xv + colorkey. > > as such emotion supports using xv "transparently" if no objects are on top of > the video, and falling back to "textured video" otherwise (gst pipeline should > work here. not sure about xine, generic/vlc). so you can get acceleration for > unobscured video, and auto-fallback if its obscured by objects on top in the > canvas (i think it doesnt handle other windows obscuring though so ymmv here). > > -- > ------------- Codito, ergo sum - "I code, therefore I am" -------------- > The Rasterman (Carsten Haitzler) ras...@rasterman.com > Thanks for the quick reply. I wasn't sure if the compositor handled 32 bit frame buffers differently already and I could hint a window to composite differently with only a bit of hacking for this and similar platforms. Maybe just customize a few shaders in the OpenGL compositing engine. For my application, having something work by luck would have been sufficient. It sounds like any way that could possible be implemented would be more complicated than, and work only as well as color keying. It's a shame that it isn't easier to make use of the multiple frame buffers and video layers on some of these SOCs. Thanks again. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ enlightenment-users mailing list enlightenment-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/enlightenment-users
