Hi Guoyin. Android Overlay has provide the no-memory-copy method. You can see swapBuffer interface in . frameworks/base/include/ui/Overlay.h.
It is similar to current ISurface:postBuffer(). But I think how it working depend on HW capibility. You can see overlay_device_t must implemented base on HW. If driver is a simple fb driver only provide 1 memory, then the for implement overlay_device_t::swapBuffer, they must do memory copy. if driver can support using 2 buffer (like v4l2 output driver), it can do swapBuffer without memory-copy. The similar issue is the size and position. If driver can't support it ,overlay_device_t implementation should do by SW method. BTW , I think createOverlay provide a video output device , NOT a simple memory. So using it just for 2-buffer is some waste. You can sent E-mail to me. (Can in Chinese) I am glad discuss with you. On 12月22日, 下午5时58分, waterblood <[email protected]> wrote: > Hi Hanchao3c, > > I just compare the overlay Android will support with Windows DDraw > interface. Just wonder whether it is possible that Android will > provided one feature as DDraw in overlay surface. > In DDraw, Overlay Surface can be created with several surfaces buffer > attach to, which are called as backup surfaces. And provide function > to swap the backup surfaces with Overlay surface. It will do some good > in video decoding. There are some codecs which need more than two > frame buffers for output. In that case , it can directly reuse the > overlay surface buffer with backup surfaces, so no memcpy needed. > So that need createOverlay can take some extra parameters to create > the backup surfaces. And swapBuffers with parameter to point to swap > specific surface. > > Thanks > Guoyin Chen > > > ========================================================= > > It seems swapBuffers just for using double-buffer. like current > > PostBuffer method/ > > Whether it can overlay more than 2 buffers depends on HW. > > Most Display HW only can support no more than 2 video plane. > > You can refer S3C24A0/PXA/OMAP data sheet. > > > But I seems there needn't using 2 HW overlay (for video ) at same > > time. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "android-framework" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-framework?hl=en -~----------~----~----~----~------~----~------~--~---
