Android 直接显示yuv数据 通过Awesomeplayer方式直接显示（三）

研究一段时间 Android的surface系统，一直执着地认为所有在surface或者屏幕上显示的画面，必须要转换成RGB才能显示，yuv数据也要通过颜色空间转换成RGB才能显示。可最近在研究stagefright视频显示时发现，根本找不到omx解码后的yuv是怎么转换成RGB的代码，yuv数据在render之后就找不到去向了，可画面确确实实的显示出来了，这从此颠覆了yuv必须要转换成RGB才能显示的真理了。

    稍微看一下AsomePlayer的代码，不难发现，视频的每一帧是通过调用了SoftwareRenderer来渲染显示的，我也尝试用利用SoftwareRenderer来直接render yuv数据显示，竟然成功了，这是一个很大的突破，比如以后摄像头采集到的yuv，可以直接丢yuv数据到surface显示，无需耗时耗效率的yuv转RGB了。

上一篇文章主要是参照AwesomePlayer直接用SoftwareRenderer类来显示yuv，为了能用到这个类，不惜依赖了libstagefright、libstagefright_color_conversion等动态静态库，从而造成程序具有很高的耦合度，也不便于我们理解yuv数据直接显示的深层次原因。

    于是我开始研究SoftwareRenderer的具体实现，我们来提取SoftwareRenderer的核心代码，自己来实现yuv的显示。

    SoftwareRenderer就只有三个方法，一个构造函数，一个析构函数，还有一个负责显示的render方法。构造方法里有个很重要的地方native_window_set_buffers_geometry这里是配置即将申请的图形缓冲区的宽高和颜色空间，忽略了这个地方，画面将用默认的值显示，将造成显示不正确。render函数里最重要的三个地方，一个的dequeBuffer，一个是mapper，一个是queue_buffer。

 native_window_set_buffers_geometry;//设置宽高以及颜色空间yuv420
 native_window_dequeue_buffer_and_wait;//根据以上配置申请图形缓冲区
 mapper.lock(buf->handle, GRALLOC_USAGE_SW_WRITE_OFTEN, bounds, &dst));//将申请到的图形缓冲区跨进程映射到用户空间
 memcpy(dst, data, dst_y_size + dst_c_size*2);//填充yuv数据到图形缓冲区
 mNativeWindow->queueBuffer;//显示

以上五步是surface显示图形必不可少的五步。

有了以上分析，我们直接上代码：(yuv数据下载地址点击打开链接，放到sdcard)

main.cpp

 #include

 #include
 #include

 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 //ANativeWindow 就是surface，对应surface.cpp里的code
 using namespace android;

 //将x规整为y的倍数,也就是将x按y对齐
 static int ALIGN(int x, int y) {
     // y must be a power of 2.
     return (x + y - 1) & ~(y - 1);
 }

 void render(
         const void *data, size_t size, const sp &nativeWindow,int width,int height) {
     sp mNativeWindow = nativeWindow;
     int err;
     int mCropWidth = width;
     int mCropHeight = height;

     int halFormat = HAL_PIXEL_FORMAT_YV12;//颜色空间
     int bufWidth = (mCropWidth + 1) & ~1;//按2对齐
     int bufHeight = (mCropHeight + 1) & ~1;

     CHECK_EQ(0,
             native_window_set_usage(
             mNativeWindow.get(),
             GRALLOC_USAGE_SW_READ_NEVER | GRALLOC_USAGE_SW_WRITE_OFTEN
             | GRALLOC_USAGE_HW_TEXTURE | GRALLOC_USAGE_EXTERNAL_DISP));

     CHECK_EQ(0,
             native_window_set_scaling_mode(
             mNativeWindow.get(),
             NATIVE_WINDOW_SCALING_MODE_SCALE_TO_WINDOW));

     // Width must be multiple of 32???
     //很重要,配置宽高和和指定颜色空间yuv420
     //如果这里不配置好，下面deque_buffer只能去申请一个默认宽高的图形缓冲区
     CHECK_EQ(0, native_window_set_buffers_geometry(
                 mNativeWindow.get(),
                 bufWidth,
                 bufHeight,
                 halFormat));


     ANativeWindowBuffer *buf;//描述buffer
     //申请一块空闲的图形缓冲区
     if ((err = native_window_dequeue_buffer_and_wait(mNativeWindow.get(),
             &buf)) != 0) {
         ALOGW("Surface::dequeueBuffer returned error %d", err);
         return;
     }

     GraphicBufferMapper &mapper = GraphicBufferMapper::get();

     Rect bounds(mCropWidth, mCropHeight);

     void *dst;
     CHECK_EQ(0, mapper.lock(//用来锁定一个图形缓冲区并将缓冲区映射到用户进程
                 buf->handle, GRALLOC_USAGE_SW_WRITE_OFTEN, bounds, &dst));//dst就指向图形缓冲区首地址

     if (true){
         size_t dst_y_size = buf->stride * buf->height;
         size_t dst_c_stride = ALIGN(buf->stride / 2, 16);//1行v/u的大小
         size_t dst_c_size = dst_c_stride * buf->height / 2;//u/v的大小

         memcpy(dst, data, dst_y_size + dst_c_size*2);//将yuv数据copy到图形缓冲区
     }

     CHECK_EQ(0, mapper.unlock(buf->handle));

     if ((err = mNativeWindow->queueBuffer(mNativeWindow.get(), buf,
             -1)) != 0) {
         ALOGW("Surface::queueBuffer returned error %d", err);
     }
     buf = NULL;
 }

 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(
             ISurfaceComposer::eDisplayIdMain));
     DisplayInfo dinfo;
     //获取屏幕的宽高等信息
     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;
     //创建surface
     sp surfaceControl = client->createSurface(String8("testsurface"),
             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];
     const char *path = "/mnt/sdcard/yuv_320_240.yuv";
     getYV12Data(path,data,size);//get yuv data from file;

 /*********************配置surface*******************************************************************/
     SurfaceComposerClient::openGlobalTransaction();
     surfaceControl->setLayer(100000);//设定Z坐标
     surfaceControl->setPosition(100, 100);//以左上角为(0,0)设定显示位置
     surfaceControl->setSize(width, height);//设定视频显示大小
     SurfaceComposerClient::closeGlobalTransaction();
     sp surface = surfaceControl->getSurface();
     printf("[%s][%d]\n",__FILE__,__LINE__);

 /**********************显示yuv数据******************************************************************/
     render(data,size,surface,width,height);
     printf("[%s][%d]\n",__FILE__,__LINE__);

     IPCThreadState::self()->joinThreadPool();//可以保证画面一直显示，否则瞬间消失
     IPCThreadState::self()->stopProcess();
     return 0;
 }

Android.mk (这次依赖的库少了很多)

 LOCAL_PATH:= $(call my-dir)
 include $(CLEAR_VARS)

 LOCAL_SRC_FILES:= \
     main.cpp

 LOCAL_SHARED_LIBRARIES := \
     libcutils \
     libutils \
     libbinder \
     libui \
     libgui \
     libstagefright_foundation

 LOCAL_MODULE:= MyShowYUV

 LOCAL_MODULE_TAGS := tests

 include $(BUILD_EXECUTABLE)

文章结尾有引用的出处，那里有相关问题的解答

渲染yuv数据的两种思考方法

思路1：在java中将Surface指针传递到jni层，lock之后就可以获得SurfaceInfo，进而取得要显示的surface格式、高度、宽度，在2.2/2.3版本，surface的Format一般都是RGB565格式，只用做一个颜色空间的转换，scaler就可以将yuv数据显示出来。
颜色空间转换和Scaler算是比较耗时的操作了。如何提高效率，scaler最好能交给android的底层函数去做，如果有gpu的，底层函数直接会利用gpu，效率非常高，又不占用cpu资源。

思路2：
   参考framework中的AwesomePlayer，里面利用AwesomeLocalRenderer/AwesomeRemoteRenderer来实现解码出来的数据显示，这个效率应该非常高，但是平台的关联性会增加很多。
   调用接口比较简单，
   首先创建一个render，
               mVideoRenderer = new AwesomeRemoteRenderer(
                mClient.interface()->createRenderer(
                        mISurface, component,
                        (OMX_COLOR_FORMATTYPE)format,
                        decodedWidth, decodedHeight,
                        mVideoWidth, mVideoHeight,
                        rotationDegrees));

  直接调用render函数就可以显示了。
    virtual void render(MediaBuffer *buffer) {
        void *id;
        if (buffer->meta_data()->findPointer(kKeyBufferID, &id)) {
            mTarget->render((IOMX::buffer_id)id);
        }
    }
  
   其它的参数都很容易获得，关键是buffer_id 怎么获得？OMXCodec.cpp中有相关的可以参考。
   实际的效果在我的S510E上跑，效率非常高，几乎不占用主控cpu资源，很可能都交给dsp和gpu去搞了。  
  

本文用Java创建UI并联合JNI层操作surface来直接显示yuv数据（yv12），开发环境为Android 4.4，全志A23平台。

package com.example.myyuvviewer;

import java.io.File;
import java.io.FileInputStream;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class MainActivity extends Activity {

    final private String TAG = "MyYUVViewer";
    final private String FILE_NAME = "yuv_320_240.yuv";
    private int width = 320;
    private int height = 240;
    private int size = width * height * 3/2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        nativeTest();
        SurfaceView surfaceview = (SurfaceView) findViewById(R.id.surfaceView);
        SurfaceHolder holder = surfaceview.getHolder();
        holder.addCallback(new Callback(){

            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                // TODO Auto-generated method stub
                Log.d(TAG,"surfaceCreated");
                byte[]yuvArray = new byte[size];
                readYUVFile(yuvArray, FILE_NAME);
                nativeSetVideoSurface(holder.getSurface());
                nativeShowYUV(yuvArray,width,height);
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format,
                    int width, int height) {
                // TODO Auto-generated method stub

            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                // TODO Auto-generated method stub

            }});
    }

    private boolean readYUVFile(byte[] yuvArray,String filename){
        try {
            // 如果手机插入了SD卡，而且应用程序具有访问SD的权限
            if (Environment.getExternalStorageState().equals(
                    Environment.MEDIA_MOUNTED)) {
                // 获取SD卡对应的存储目录
                File sdCardDir = Environment.getExternalStorageDirectory();
                // 获取指定文件对应的输入流
                FileInputStream fis = new FileInputStream(
                        sdCardDir.getCanonicalPath() +"/" + filename);
                fis.read(yuvArray, 0, size);
                fis.close();
                return true;
            } else {
                return false;
            }
        }catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
    private native void nativeTest();
    private native boolean nativeSetVideoSurface(Surface surface);
    private native void nativeShowYUV(byte[] yuvArray,int width,int height);
    static {
        System.loadLibrary("showYUV");
    }
}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <SurfaceView
        android:id="@+id/surfaceView"
        android:layout_width="fill_parent"
        android:layout_height="360dp" />

LinearLayout>

JNI层，showYUV.cpp(libshowyuv.so)采用动态注册JNI函数的方法.

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
using namespace android;

static sp surface;

static int ALIGN(int x, int y) {
    // y must be a power of 2.
    return (x + y - 1) & ~(y - 1);
}

static void render(
        const void *data, size_t size, const sp &nativeWindow,int width,int height) {
    ALOGE("[%s]%d",__FILE__,__LINE__);
    sp mNativeWindow = nativeWindow;
    int err;
    int mCropWidth = width;
    int mCropHeight = height;

    int halFormat = HAL_PIXEL_FORMAT_YV12;//颜色空间
    int bufWidth = (mCropWidth + 1) & ~1;//按2对齐
    int bufHeight = (mCropHeight + 1) & ~1;

    CHECK_EQ(0,
            native_window_set_usage(
            mNativeWindow.get(),
            GRALLOC_USAGE_SW_READ_NEVER | GRALLOC_USAGE_SW_WRITE_OFTEN
            | GRALLOC_USAGE_HW_TEXTURE | GRALLOC_USAGE_EXTERNAL_DISP));

    CHECK_EQ(0,
            native_window_set_scaling_mode(
            mNativeWindow.get(),
            NATIVE_WINDOW_SCALING_MODE_SCALE_CROP));

    // Width must be multiple of 32???
    //很重要,配置宽高和和指定颜色空间yuv420
    //如果这里不配置好，下面deque_buffer只能去申请一个默认宽高的图形缓冲区
    CHECK_EQ(0, native_window_set_buffers_geometry(
                mNativeWindow.get(),
                bufWidth,
                bufHeight,
                halFormat));


    ANativeWindowBuffer *buf;//描述buffer
    //申请一块空闲的图形缓冲区
    if ((err = native_window_dequeue_buffer_and_wait(mNativeWindow.get(),
            &buf)) != 0) {
        ALOGW("Surface::dequeueBuffer returned error %d", err);
        return;
    }

    GraphicBufferMapper &mapper = GraphicBufferMapper::get();

    Rect bounds(mCropWidth, mCropHeight);

    void *dst;
    CHECK_EQ(0, mapper.lock(//用来锁定一个图形缓冲区并将缓冲区映射到用户进程
                buf->handle, GRALLOC_USAGE_SW_WRITE_OFTEN, bounds, &dst));//dst就指向图形缓冲区首地址

    if (true){
        size_t dst_y_size = buf->stride * buf->height;
        size_t dst_c_stride = ALIGN(buf->stride / 2, 16);//1行v/u的大小
        size_t dst_c_size = dst_c_stride * buf->height / 2;//u/v的大小

        memcpy(dst, data, dst_y_size + dst_c_size*2);//将yuv数据copy到图形缓冲区
    }

    CHECK_EQ(0, mapper.unlock(buf->handle));

    if ((err = mNativeWindow->queueBuffer(mNativeWindow.get(), buf,
            -1)) != 0) {
        ALOGW("Surface::queueBuffer returned error %d", err);
    }
    buf = NULL;
}

static void nativeTest(){
    ALOGE("[%s]%d",__FILE__,__LINE__);
}

static jboolean
nativeSetVideoSurface(JNIEnv *env, jobject thiz, jobject jsurface){
    ALOGE("[%s]%d",__FILE__,__LINE__);
    surface = android_view_Surface_getSurface(env, jsurface);
    if(android::Surface::isValid(surface)){
        ALOGE("surface is valid ");
    }else {
        ALOGE("surface is invalid ");
        return false;
    }
    ALOGE("[%s][%d]\n",__FILE__,__LINE__);
    return true;
}
static void
nativeShowYUV(JNIEnv *env, jobject thiz,jbyteArray yuvData,jint width,jint height){
    ALOGE("width = %d,height = %d",width,height);
    jint len = env->GetArrayLength(yuvData);
    ALOGE("len = %d",len);
    jbyte *byteBuf = env->GetByteArrayElements(yuvData, 0);
    render(byteBuf,len,surface,width,height);
}
static JNINativeMethod gMethods[] = {
    {"nativeTest",                  "()V",                              (void *)nativeTest},
    {"nativeSetVideoSurface",       "(Landroid/view/Surface;)Z",        (void *)nativeSetVideoSurface},
    {"nativeShowYUV",               "([BII)V",                          (void *)nativeShowYUV},
};

static const char* const kClassPathName = "com/example/myyuvviewer/MainActivity";

// This function only registers the native methods
static int register_com_example_myyuvviewer(JNIEnv *env)
{
    ALOGE("[%s]%d",__FILE__,__LINE__);
    return AndroidRuntime::registerNativeMethods(env,
                kClassPathName, gMethods, NELEM(gMethods));
}

jint JNI_OnLoad(JavaVM* vm, void* reserved)
{
    ALOGE("[%s]%d",__FILE__,__LINE__);
    JNIEnv* env = NULL;
    jint result = -1;

    if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
        ALOGE("ERROR: GetEnv failed\n");
        goto bail;
    }
    assert(env != NULL);
    ALOGE("[%s]%d",__FILE__,__LINE__);
   if (register_com_example_myyuvviewer(env) < 0) {
        ALOGE("ERROR: MediaPlayer native registration failed\n");
        goto bail;
    }

    /* success -- return valid version number */
    result = JNI_VERSION_1_4;

bail:
    return result;
}

Android.mk

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES:= \
    showYUV.cpp

LOCAL_SHARED_LIBRARIES := \
    libcutils \
    libutils \
    libbinder \
    libui \
    libgui \
    libandroid_runtime \
    libstagefright_foundation

LOCAL_MODULE:= libshowYUV

LOCAL_MODULE_TAGS := tests

include $(BUILD_SHARED_LIBRARY)

生成的so文件复制到Java项目里 与src并列的libs/armeabi目录下，没有就手动创建目录，

这样Eclipse会自动把so库打包进apk。

转载请注明出处：http://blog.csdn.net/tung214/article/details/37762487

yuvdata下载地址：点击打开链接