yuv数据

    
YUV420数据拷贝：    
int picSize = codec_->height * codec_->width;
    int newSize = picSize * 1.5;

    //申请内存
    unsigned char *buf = new unsigned char[newSize];

    int height = p->codec->height;
    int width = p->codec->width;


    //写入数据
    int a=0,i; 
    for (i=0; i<height; i++) 
    { 
        memcpy(buf+a,pFrame_->data[0] + i * pFrame_->linesize[0], width); 
        a+=width; 
    } 
    for (i=0; i<height/2; i++) 
    { 
        memcpy(buf+a,pFrame_->data[1] + i * pFrame_->linesize[1], width/2); 
        a+=width/2; 
    } 
    for (i=0; i<height/2; i++) 
    { 
        memcpy(buf+a,pFrame_->data[2] + i * pFrame_->linesize[2], width/2); 
        a+=width/2; 
    }

    //===============
    //到这里，buf里面已经是yuv420p的数据了，可以对它做任何的处理拉！
    //===============
    delete [] buf;