iblues, I am trying to display some yuv dump on to the screen .Can you tell me how u did it in ur case ? did u write a jni wrapper to access the display surface ? Is it possible to render on to the display without a jni wrapper ? I don't want to introduce JNI at present . I know one cannot access the display from a native application but I have read that it is possible which myt not work later. As of now i just want to display something on the screen.
On Jan 23, 6:21 am, iblues <[email protected]> wrote: > Thanks Dave. > > Regards, > iblues > > On Jan 23, 10:40 am, Dave Sparks <[email protected]> wrote: > > > 1. ISurface is the remote interface for SurfaceFlinger. When you call > > an ISurface method like postBuffer, you are executing an RPC in > > SurfaceFlinger. There is only one way to render 2D graphics through > > the window system and that is using SurfaceFlinger. In the future, you > > could use the overlay interface, but that is aimed more at hardware > > pipelined video rather than software rendering. > > > 2. ashmem and pmem are very similar. Both are used for sharing memory > > between processes. ashmem uses virtual memory, whereas pmem uses > > physically contiguous memory. One big difference is that with ashmem, > > you have a ref-counted object that can be shared equally between > > processes. For example, if two processes are sharing an ashmem memory > > buffer, the buffer reference goes away when both process have removed > > all their references by closing all their file descriptors. pmem > > doesn't work that way because it needs to maintain a physical to > > virtual mapping. This requires the process that allocates a pmem heap > > to hold the file descriptor until all the other references are closed. > > > 3. You have the right idea for using shared memory. The choice between > > ashmem and pmem depends on whether you need physically contiguous > > buffers. In the case of the G1, we use the hardware 2D engine to do > > scaling, rotation, and color conversion, so we use pmem heaps. The > > emulator doesn't have a pmem driver and doesn't really need one, so we > > use ashmem in the emulator. If you use ashmem on the G1, you lose the > > hardware 2D engine capability, so SurfaceFlinger falls back to its > > software renderer which does not do color conversion, which is why you > > see the monochrome image. > > > On Jan 22, 8:46 pm, iblues <[email protected]> wrote: > > > > Hi Dave, > > > > I was able to display the YUV frame onto the ISurface. But as you had > > > mentioned, the emulator is considering only the Y-data and displaying > > > a gray-scale video. I just have few clarifications from my above > > > exercise : > > > > 1. In most of the posts and also in the source code, whenever we talk > > > to posting to the display, all talk of Surface Flinger whereas the > > > Camera and the Media Player uses ISurface to render the display images > > > onto the screen. I also see the implementation of the Surface Flinger > > > to be more of a wrapper to the ISurface. Which of these objects would > > > you recommend to be used for real-time rendering of YUV data? > > > > 2. I seem to not to understand the difference between ashmemory and > > > pmem memory. Can you point out some overall differences between the > > > same? > > > > 3. In my requirement, I would have a native library A render the YUV > > > frames and map it to a Memory Heap. If another library say B wants to > > > have access to this memory heap , as per my understanding, I will have > > > to wrap the memory heap into IMemory and pass the same via a callback > > > from A to B right? If so, should my memory heap type be ashmem or > > > pmem? > > > > Please correct me if my understandings are wrong anywhere. > > > > Regards, > > > Syed Ibrahim M > > > > -------------------------- > > > > On Jan 22, 12:33 am, Dave Sparks <[email protected]> wrote: > > > > > Yes, you need to make your class a friend of SurfaceHolder.- Hide > > > > quoted text - > > > - Show quoted text - > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
