On Tue, 23 Feb 2016 10:11:39 +0900 YoungJun Jo <dtoart...@gmail.com> wrote:
> Hello, > > Thanks for your reply. > > What i want is alpha blending for my chips. > As i mentioned, My chips have four independent H/W overlays. > > For example, > H/W Overlay 1 => Weston, Applications, etc.. > H/W Overlay 2 => Video play. > H/W Overlay 3 = > Empty. > H/W Overlay 4 = > Empty. > > I also know that weston don't know H/W Overlays above mentioned. Hi, ok. The current state of Weston is slightly sad, as the support for hardware overlays is disabled by default, because enabling it causes performance problems. All that will be fixed once the patch series to support atomic/nuclear KMS in the DRM backend by Daniel Stone will land. I think Daniel is polishing it for submission whenever he has time for it. I would expect the situation to improve for Weston 1.11, but that's no promise. Btw. if you are using an fbdev backed, you have already lost: it will never support hardware overlays. Use the DRM-backend instead. It is possible to activate overlay support already with the debug key binding Mod+Shift+space, v. > Scenario: > 1. If i click play button on my video application, it will be call alpha > blending API. > 2. When weston receives alpha blending api, weston background will be > transparent. > 3. And i could see video playing from H/W Layer 2.(Still H/W Layer1 shows > GUI of video control buttons) > > So i want really alpha blending of weston background. I suppose you could do it like that, assuming that: - you will only ever support your one special video player - your video player is not cooperating with the display server, but it is bypassing the display server instead and holding the display server as a hostage (otherwise the display server, e.g. weston, can mess up your video view) - your video player is likely specific to your hardware and cannot work elsewhere - you will have to use a modified Weston, as upstream will never accept what you would need for this - you will need to create a protocol extension for the "alpha blending API" or whatever to tell weston to get out of the way - you won't have any application window mapped while playing e.g. fullscreen video - you will waste power by always having to have a fullscreen completely transparent overlay on top the video overlay, rather than having the video on the top-most overlay and probably many more limitations that make the approach very painful to use in anything but a simple single-purpose device with a throw-away software stack. Essentially, you are using a display server (weston) to get a window system, and then your aim is to remove the window system and bypass the display server, telling weston to not mess with your video player. Btw. I forgot a few things earlier. Not only you need to have the backend tell the renderer use an alpha-capable framebuffer format, you also need to hack clients/desktop-shell.c to not force the background to be opaque. I'm not sure, but there might also be further things to adjust in a backend to make sure the alpha bits actually get into the hardware. The proper solution using Wayland and Weston as they are intended would involve the following: - ensure your display hardware has proper DRM drivers supporting atomic KMS - wait for the atomic support to land in Weston, which... - puts Weston in control of all hardware planes, so that... - Weston will automatically use all hardware planes for everything it can - use any general purpose video player you want which supports linux_dmabuf Wayland protocol extension... - and that will get the video on the hw overlay automatically when it is possible, and through hardware accelerated composition when the overlay cannot be used. When the video player uses EGL or linux_dmabuf to push the video frames to Weston, then Weston has the possibility to show them on a hardware overlay. As Weston will be in charge of everything on the display, the fullscreen video playback won't suffer from the same waste of power as your approach. The proper solution is likely to result in a near-optimal use of hardware resources in all cases automatically, both where overlays can and cannot be used. The proper solution is also generic in that it is not tied to a particular hardware platform. In summary, do what you must, but I would strongly recommend the proper solution if at all possible for you. Thanks, pq > 2016-02-22 21:36 GMT+09:00 YoungJun Jo <dtoart...@gmail.com>: > > > Environment > > OS : Linux kernel 3.10 > > Version : Weston 1.8.0 > > H/W spec : embedded soc based on ARM > > > > Hello, All > > > > I have a question about weston background. > > I want enable alpha blending to background, so i have typed > > 'background-color=0x00ffffff' on weston.ini. > > But that's not really alpha blending. Because alpha value of pixel is a > > 'ff'. > > My chips have four H/W layers, top of the layer is UI layer and second > > layer is video layer. > > > > I reviewed source code of 'desktop-shell.c' but i can't find any hints. > > > > Need some additional ideas to solve this problem. Any feedback is > > appreciated. > > > > Thanks. > >
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