DM648视频输出图像差，求助啊

前端是TVP5154，后端是SAA7105，采集和显示代码如下：

    /* loop forever performing video capture and display */
    while (status == 0) {

       /* grab a fresh video input frame */
       if(IOM_COMPLETED != FVID_exchange(capChan, &frameBuffPtr))
       {     return;
       } 
       /* display the video frame */
       if(IOM_COMPLETED != FVID_exchange(disChan, &frameBuffPtr)) ---------------------------在此处设置断点
       {
     return;
       } 
    } 

设置断点后，根据frameBuffPtr的数据，在CCS中用view->graph->image画图，图片如下：

继续执行后，最终在屏幕上图像为：

参数设置都是按照TI的例程来的，如下：

#if (CFG_VIDEO_MODE == MODE_PAL)

/* Vport Capture driver configuration.Using embedded sync */
static VPORTCAP_Params vCapParamsChan = CAP_PARAMS_CHAN_BT656_DEFAULT(PAL);

/* TVP5154 EDC driver configuration.Using embedded sync and Composite Analog Channel A for all 8 decoders */
static TVP5154_ConfParams vCapParamsDecoder
                   = CAP_PARAMS_TVP5154_EMBEDDED_DEFAULT(PAL, COMPOSITE_A);

/* Vport Display driver configuration.Using embedded sync */
static VPORTDIS_Params vDisParamsChan = DIS_PARAMS_CHAN_BT656_DEFAULT(PAL);

/* SAA7105 EDC driver configuration.Using Svideo Analog output */
static SAA7105_ConfParams vDisParamsEncoder = DIS_PARAMS_SAA7105_SDTV_EMBEDDED_DEFAULT(PAL720, COMPOSITE);
#endif

SAA7105周边硬件电路基本没啥问题，求高手指导~~~~~~~~~~~~~~~~~~~~~~