how to copy other frame buffer with ffmpeg - ffmpeg

Question

I have a question for frame copy with other position.
I got a 1280640 decoded frame (YUV420) from h264/mp4 and I wanna merge 4 frame to 25601280 frame buffer . as below.
enter image description here
The code is like this but does not working.
enter code here
/* pCodecCtx and pFrame for decoded frame information */
int Encoding2JPEG( AVCodecContext *pCodecCtx, AVFrame *pFrame, int FrameNo, int Quality)
{
int gotFrame;
/* New Context for JPEG encoding */
AVCodec *jpeg_codec = NULL;
AVCodecContext *jpeg_ctx =NULL;
int ret;
AVPacket *packet;
packet = av_packet_alloc();
if(!packet)
{
printf("alloc fail!\n");
return -1;
}
if(frame)
printf("received frame for encoding %3"PRId64"\n", frame->pts);
pFrame_gather = av_frame_alloc();
if(!pFrame_gather)
{
printf("Could not allocate gater frame!\n");
return -1;
}
pFrame_gather->format = pCodecCtx->pix_fmt;
pFrame_gather->width = pCodecCtx->width*2;
pFrame_gather->height = pCodecCtx->height*2;
if ( av_frame_get_buffer(pFrame_gather, 0) < 0)
printf("Could not allocate the gather frame data!\n");
/* Buffer Clear */
ptrdiff_t linesize[4] = { frame->linesize[0], 0, 0, 0 };
if( av_image_fill_black ( pFrame_gather->data, linesize, pCodecCtx->pix_fmt, \
AVCOL_RANGE_JPEG , pFrame_gather->width, pFrame_gather->height) != 0 )
printf("image clear error!\n");
ret = av_frame_make_writable(pFrame_gather);
if( ret <0)
printf("writeable set fail!\n");
/* set position of destination */
int top_band =0;
int left_band=200;
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pCodecCtx->pix_fmt);
int y_shift;
int x_shift;
int max_step[4];
if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
return -1;
y_shift = desc->log2_chroma_h;
x_shift = desc->log2_chroma_w;
av_image_fill_max_pixsteps(max_step, NULL, desc);
/* Y Data */
memcpy( pFrame_gather->data[0] + (top_band * pFrame->linesize[0]) + left_band,\
frame->data[0] , pCodecCtx->width*pCodecCtx->height);
/* U Data */
memcpy ( pFrame_gather->data[1] + ((top_band >> y_shift) * pFrame->linesize[1]) + \
(left_band >> x_shift), frame->data[1], pCodecCtx->width/2*pCodecCtx->height/2);
/* V DAta */
memcpy ( pFrame_gather->data[2] + ((top_band >> y_shift) * pFrame->linesize[2]) \
+ (left_band >> x_shift), frame->data[2], pCodecCtx->width/2*pCodecCtx->height/2);
/* unref variable .... */
....
}
Upper source code is something wring. It does not working.
How to memory copy with position?