Android 直接显示yuv数据 通过Awesomeplayer方式直接显示（二）

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)

转载请注明出处 http://blog.csdn.net/tung214/article/details/37651825