请教达人，如何使用Xv extension。显示ffmpeg解码出来的视频。

dxzk7

近来小弟用Xv extension在Qt下显示ffmpeg解码出来的YUV视频。解码过程是正常的。

使用xvinfo显示我在虚拟机中的显卡支持 YV12 模式的视频。当然YV12 和YUV的差异很小。我使用如下代码来显示。但是得到是一个黑的窗体。也就是什么都没给我显示。请教各位大侠。这是何解。

            AVFrame *pFrame;             AVFrame *Frame;             AVPicture pict;                                      int frameFinished;             pFrame = avcodec_alloc_frame();             Frame = avcodec_alloc_frame();             avcodec_decode_video(avctx,                                 pFrame,                                 &frameFinished,                                 (unsigned char *)pStreamData+12,                                 pFrameHead->nByteNum);                                                       if(frameFinished)             {                 printf("I");                                  XvImage *image = XvCreateImage(dpy, port, 0x32315659, NULL, avctx->width, avctx->height);                 image->data = malloc(image->data_size);                                  pict.data[0] = image->data+image->offsets[0];                 pict.data[1] = image->data+image->offsets[2];                 pict.data[2] = image->data+image->offsets[1];                                  pict.linesize[0] = image->pitches[0];                 pict.linesize[1] = image->pitches[2];                 pict.linesize[2] = image->pitches[1];                                  img_convert(&pict,PIX_FMT_YUV420P,                             pFrame, PIX_FMT_YUV420P,                             avctx->width, avctx->height);                                                              /*                                  Frame->data[0] = pFrame->data[0];             Frame->data[1] = pFrame->data[2];             Frame->data[2] = pFrame->data[1];                              Frame->linesize[0] = pFrame->linesize[0];             Frame->linesize[1] = pFrame->linesize[2];             Frame->linesize[2] = pFrame->linesize[1];                          //XvImage *image = XvCreateImage(dpy, port, 0x32315659, Frame->data[0], 640, 480);             XvImage *image = XvShmCreateImage(dpy, port, 0x32315659, avctx->width, avctx->height, NULL);             */                          XvPutImage(dpy,port,win,gc,image,                                      0,0,avctx->width, avctx->height,                                      0,0,704,576);                                                         XFlush(dpy);                                     XFree(image);             }                                         av_free(Frame);             av_free(pFrame);