求助 RV1126 VMIX的使用方法或者绘制多个框的方法

目前已经可以实现用RK_MPI_VENC_RGN_SetBitMap来绘制字符，但如果需要绘制多个框，需要共用一个region，每次后续添加或删除框都需要重新绘制bitmap，在计算上来说有些麻烦。
原流程：VI->VENC(OSD->VENC_RGN)->rtsp
增加VMIX：VI->VMIX->VENC(OSD->VENC_RGN)->rtsp
查阅文档发现VMIX有个接口RK_MPI_VMIX_SetLineInfo，需要有两个码流0和1，打印显示码流0成功绑定了，调用这个接口也没有绘制出框，而且码流1报错”RK_MPI_SYS_Bind Dst Mode[VMIX]:Chn[1] is not ready!”
求助各位大佬有没有用过VMIX的经验或者绘制多个框的方法，万分感谢！

////////////
ret = RK_MPI_VI_SetChnAttr(0, stream_id, &vi_chn_attr);
ret |= RK_MPI_VI_EnableChn(0, stream_id);
////////////
ret = RK_MPI_VENC_CreateChn(stream_id, &chn_attr);
////////////
int vmix_init(int stream_id, int width, int height)
{
    VMIX_DEV_INFO_S stDevInfo;
    stDevInfo.enImgType = IMAGE_TYPE_NV12;
    stDevInfo.u16ChnCnt = 1;
    stDevInfo.u16Fps = 15;
    stDevInfo.u32ImgWidth = width;
    stDevInfo.u32ImgHeight = height;
    stDevInfo.bEnBufPool = RK_TRUE;
    stDevInfo.u16BufPoolCnt = 3;

    stDevInfo.stChnInfo[0].enImgInType = IMAGE_TYPE_NV12;
    stDevInfo.stChnInfo[0].enImgOutType = IMAGE_TYPE_NV12;
    stDevInfo.stChnInfo[0].stInRect.s32X = 0;
    stDevInfo.stChnInfo[0].stInRect.s32Y = 0;
    stDevInfo.stChnInfo[0].stInRect.u32Width = width;
    stDevInfo.stChnInfo[0].stInRect.u32Height = height;
    stDevInfo.stChnInfo[0].stOutRect.s32X = 0;
    stDevInfo.stChnInfo[0].stOutRect.s32Y = 0;
    stDevInfo.stChnInfo[0].stOutRect.u32Width = width;
    stDevInfo.stChnInfo[0].stOutRect.u32Height = height;

    int ret = RK_MPI_VMIX_CreateDev(stream_id, &stDevInfo);
    if (ret)
    {
        PRINT_WARN("Init VMIX device failed! ret=%d\n", ret);
        return -1;
    }

    ret = RK_MPI_VMIX_EnableChn(stream_id, 0);
    if (ret)
    {
        PRINT_WARN("Enable VM[0]:Chn[0] failed! ret=%d\n", ret);
        return -1;
    }

    PRINT_INFO("create vm[%d] success\n", stream_id);
    return 0;
}

int chn_bind(int stream_id)
{
    assert(stream_id <= MAX_MEDIA_STREAM_CNT);
    MPP_CHN_S stSrcChn;
    stSrcChn.enModId = RK_ID_VI;
    stSrcChn.s32DevId = 0;
    stSrcChn.s32ChnId = stream_id;
    MPP_CHN_S stDestChn;
    stDestChn.enModId = RK_ID_VMIX;
    stDestChn.s32DevId = 0;
    stDestChn.s32ChnId = stream_id;
    int ret = RK_MPI_SYS_Bind(&stSrcChn, &stDestChn);
    if (ret)
    {
        PRINT_WARN("ERROR: Bind VI[%d] and VMIX[%d] error! ret=%d\n", stream_id, stream_id, ret);
        return -1;
    }
    PRINT_INFO("Bind VI[%d] and VMIX[%d] success\n", stream_id, stream_id);

    stSrcChn.enModId = RK_ID_VMIX;
    stSrcChn.s32DevId = 0;
    stSrcChn.s32ChnId = stream_id;
    stDestChn.enModId = RK_ID_VENC;
    stDestChn.s32DevId = 0;
    stDestChn.s32ChnId = stream_id;
    ret = RK_MPI_SYS_Bind(&stSrcChn, &stDestChn);
    if (ret)
    {
        PRINT_WARN("ERROR: Bind VMIX[%d] and VENC[%d] error! ret=%d\n", stream_id, stream_id, ret);
        return -1;
    }
    PRINT_INFO("Bind VMIX[%d] and VENC[%d] success\n", stream_id, stream_id);

    RK_MPI_SYS_SetMediaBufferDepth(RK_ID_VENC, stream_id, 3);

    return -1;
}