Android uses surface to directly display yuv data

After studying the surface system of Android for a while, I persistently think that all the pictures displayed on the surface or screen must be converted to RGB for display, yuv data can be displayed only when the color space is converted to RGB. Recently, when studying stagefright video display, we found that we could not find how the yuv decoded by omx was converted to RGB code, and yuv data could not be found after render, the screen is indeed displayed, which subverts the truth that yuv must be converted to RGB to display.

Taking a look at the AsomePlayer code, it is not difficult to find that each frame of the video is rendered and displayed by calling SoftwareRenderer. I also try to use SoftwareRenderer to directly display render yuv data, this is a big breakthrough. For example, the yuv data collected by the camera in the future can be directly lost to the surface display, without the need to convert the time-consuming yuv to RGB.

The code is original and posted to share with you: Android 4.4 platform (here, you can download the yuv data address and click here to open the link and put it in the/mnt/sdcard directory)

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              Using namespace android; bool getYV12Data (const char * path, unsigned char * pYUVData, int size) {FILE * fp = fopen (path, "rb "); if (fp = NULL) {printf ("read % s fail !!!!!!!!!!!!!!!!!!! \ N ", path); return false;} fread (pYUVData, size, 1, fp); fclose (fp); return true;} int main (void) {// set up the thread-pool sp
             
               Proc (ProcessState: self (); ProcessState: self ()-> startThreadPool (); // create a client to surfaceflinger sp
              
                Client = new SurfaceComposerClient (); sp
               
                 Dtoken (SurfaceComposerClient: getBuiltInDisplay (metadata: eDisplayIdMain); DisplayInfo dinfo; // gets the screen width and height information status_t status = SurfaceComposerClient: getDisplayInfo (dtoken, & dinfo ); printf ("w = % d, h = % d, xdpi = % f, ydpi = % f, fps = % f, ds = % f \ n", dinfo. w, dinfo. h, dinfo. xdpi, dinfo. ydpi, dinfo. fps, dinfo. density); if (status) return-1; // create a surface. Some systems may report an error, dinfo. w and dinfo. h can also be written as a fixed value sp
                
                  SurfaceControl = client-> createSurface (String8 ("showYUV"), dinfo. w, dinfo. h, PIXEL_FORMAT_RGBA_8888, 0);/************************* get yuv data from file; **************************************** /printf ("[% s] [% d] \ n ", __file __,__ LINE _); int width, height; width = 320; height = 240; int size = width * height * 3/2; unsigned char * data = new unsigned char [size]; char * path = "/mnt/sdcard/yuv_320_240.yuv"; getYV12Data (path, data, size ); // get yuv data from file; /********************* configure the surface **************** **************************************** * **********/SurfaceComposerClient:: openGlobalTransaction (); surfaceControl-> setLayer (100000); // set zcoordinate surfaceControl-> setPosition (100,100); // set the upper left corner) set the display position surfaceControl-> setSize (width, height); // set the video display size SurfaceComposerClient: closeGlobalTransaction (); sp
                 
                   Surface = surfaceControl-> getSurface (); printf ("[% s] [% d] \ n" ,__ FILE __,__ LINE __); /*************************************** **************************************** * ********/sp
                  
                    Meta = new MetaData; meta-> setInt32 (kKeyWidth, width); meta-> setInt32 (kKeyHeight, height);/* specify the yuv format and support the following yuv format: * OMX_COLOR_FormatYUV420Planar: * metadata: * HAL_PIXEL_FORMAT_YV12: * others may be converted to OMX_COLOR_Format16bitRGB565 */meta-> setInt32 (kKeyColorFormat, HAL_PIXEL_FORMAT_YV12). // setRect is not required, I do not know what is the purpose and principle of the settings, but set the parameters correctly. meta-> setRect (kKeyCropRect, 0, // left 0, // top width-1, // right height-1); // bottomprintf ("[% s] [% d] \ n" ,__ FILE __, __line _); SoftwareRenderer * sr = new SoftwareRenderer (surface, meta); // initialize printf ("[% s] [% d] \ n" ,__ FILE __, __line _); sr-> render (data, size, NULL); // The Key is displayed here, and delete [] data; printf ("[% s] [% d] \ n" ,__ FILE __,__ LINE _); IPCThreadState: self ()-> joinThreadPool (); // ensure that the image is always displayed; otherwise, IPCThreadState: self ()-> stopProcess (); return 0;} will disappear instantly ;}
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     
    
   
  
 

LOCAL_PATH:= $(call my-dir)include $(CLEAR_VARS)LOCAL_SRC_FILES:= \main.cppLOCAL_STATIC_LIBRARIES := \libstagefright_color_conversionLOCAL_SHARED_LIBRARIES := \libcutils \libutils \libbinder \    libui \    libgui \libstagefright\libstagefright_foundationLOCAL_C_INCLUDES := \frameworks/native/include/media/openmax \    frameworks/av/media/libstagefrightLOCAL_MODULE:= showYUVLOCAL_MODULE_TAGS := testsinclude $(BUILD_EXECUTABLE)