DM8168中，jpg编码如何修改起始坐标

请问各位大神，如何调整图像编码的起始位置，在264格式的编码过程中，修改

Int32 Enclink_h264EncodeFrameBatch(EncLink_Obj * pObj,EncLink_ReqBatch * reqObjBatch,Int32 tskId)

中函数process的输入参数，如下

/////////////修改编码起始坐标///////////////////

inputBufDesc->activeFrameRegion.topLeft.x = 200;

inputBufDesc->activeFrameRegion.topLeft.y = 200;

inputBufDesc->activeFrameRegion.bottomRight.x = 2120;

inputBufDesc->activeFrameRegion.bottomRight.y = 1280;

inputBufDesc->imageRegion.topLeft.x = 200;

inputBufDesc->imageRegion.topLeft.y = 200;

inputBufDesc->imageRegion.bottomRight.x = 2120;

inputBufDesc->imageRegion.bottomRight.y = 1280;

///////////////////////////////////////////////////////

processList.processParams[processList.numEntries].inBufs = inputBufDesc;

processList.processParams[processList.numEntries].outBufs = outputBufDesc;

结果表明编出来的图像左上角起点确实是从原图像(200,200)这个坐标处开始的

但是我按照同样的方法修改jpg编码通道，具体为

Int32 Enclink_jpegEncodeFrame(EncLink_ChObj * pChObj, EncLink_ReqObj * pReqObj)

中，

///////////////////////修改编码起始坐标/////////////////////////////

inputBufDesc->activeFrameRegion.topLeft.x = 200;

inputBufDesc->activeFrameRegion.topLeft.y = 200;

inputBufDesc->activeFrameRegion.bottomRight.x = 2120;

inputBufDesc->activeFrameRegion.bottomRight.y = 1280;

inputBufDesc->imageRegion.topLeft.x = 200;

inputBufDesc->imageRegion.topLeft.y = 200;

inputBufDesc->imageRegion.bottomRight.x = 2120;

inputBufDesc->imageRegion.bottomRight.y = 1280;

////////////////////////////////////

error =handle->fxns->ividenc.process((IVIDENC2_Handle) handle,inputBufDesc, outputBufDesc,(IVIDENC2_InArgs *) inArgs,(IVIDENC2_OutArgs *) outArgs);

但是编出来图像没有任何变化，打日志表明程序运行时确实调用了这个函数，请问jpg要实现类似的功能是还需要修改别的参数吗，还是用的rdk版本不支持，我用的是DVRRDK4.0版