3D视频上下转化左右交织格式YUV

3D视频中，有的是上下格式的，但是无论是裸眼3D还是3D眼镜都需要左右格式的，下面就是转换的算法，利用ffmpeg解码，进行YUV切割，实现左右视频交织，可以在裸眼3D手机或者pad上观看3D效果。必须要先熟悉YUV数据格式。

        FILE *yuvFile = fopen("yuv_file_width.yuv","ab");
	if(!yuvFile)
		return 0;
	av_register_all();
	AVFormatContext *pFormat  = NULL;
	if (avformat_open_input(&pFormat ,SRC_FILE,NULL,NULL) < 0)
	{
		return 0;
	}
	AVCodecContext * video_dec_ctx = NULL;
	AVCodec *video_dec = NULL;
	if (avformat_find_stream_info(pFormat,NULL) < 0)
	{
		return 0;
	}
	av_dump_format(pFormat,0,SRC_FILE,0);
	int index = -1,i = 0;
	for (i=0;i<pFormat->nb_streams;i++)
	{
		if (pFormat->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			index = i;
			break;
		}
	}
	if (-1 == index)
	{
		printf("can‘t find the codec\n");
		return -1;
	}
	video_dec_ctx = pFormat->streams[index]->codec;
	video_dec = avcodec_find_decoder(video_dec_ctx->codec_id);
	//源文件的格式上下文 解码器上下文  解码器 都已经找到 现在打开解码器
	if(avcodec_open2(video_dec_ctx,video_dec,NULL) < 0)
	{
		return 0;
	}

	//需要读取一帧数据 放在包里
	AVPacket *video_pkt =  new AVPacket;
	av_init_packet(video_pkt);

	while (1)
	{
		if(av_read_frame(pFormat,video_pkt)<0)
		{
			fclose(yuvFile);
			delete video_pkt;
			return 0;
		}
		if (pFormat->streams[video_pkt->stream_index]->codec->codec_type ==       AVMEDIA_TYPE_VIDEO)
		{
			AVFrame *frame =avcodec_alloc_frame();
			int got_pictrue = 0,ret = 0;
			ret = avcodec_decode_video2(video_dec_ctx,frame,&got_pictrue,video_pkt);
			if (ret < 0)
			{
				continue;
			}
			if (got_pictrue)
			{
				printf("decode one frame is ok\n");
				int height = video_dec_ctx->height/2;
				int width = video_dec_ctx->width*2;
				char *buf = new char[height*width*3/2];
				memset(buf,0,height*width*3/2);
				int y_tmp=0,i=0;
				int u_tmp = width/2*height*2;
				int v_tmp = u_tmp + width/4*height/2*2;

				for (i=0;i<height;i++)
				{
					int tmp;
					memcpy(buf+y_tmp,frame->data[0]+i*frame->linesize[0],width/2);
					y_tmp += width/2;
					tmp = i+height;
					memcpy(buf+y_tmp,frame->data[0]+tmp*frame->linesize[0],width/2);
					y_tmp += width/2;
					if (i<height/2)
					{
						memcpy(buf+u_tmp,frame->data[1]+i*frame->linesize[1],width/4);
						u_tmp += width/4;
						tmp = i+height/2;
						memcpy(buf+u_tmp,frame->data[1]+tmp*frame->linesize[1],width/4);
						u_tmp += width/4;

						memcpy(buf+v_tmp,frame->data[2]+i*frame->linesize[2],width/4);
						v_tmp += width/4;
						tmp = i+height/2;
						memcpy(buf+v_tmp,frame->data[2]+tmp*frame->linesize[2],width/4);
						v_tmp += width/4;
					}
				}

				int frame_height = height;
				int frame_width = width/2;
				char *frame_buf = new char[frame_height*frame_width*3/2];
				memset(frame_buf,0,frame_height*frame_width*3/2);
				int tmp=0;
				for (i=0;i<height*width*3/2;i++)
				{
					if (i%2 == 0)
					{
						memcpy(frame_buf+tmp,buf+i,1);
						tmp++;
					}

				}
				for (i=0;i<height;i++)
				{
				memcpy(buf+a,frame->data[0]+i*frame->linesize[0],width);
				a += width;
				}
				for (i=0;i<height/2;i++)
				{
				memcpy(buf+a,frame->data[1]+i*frame->linesize[1],width/2);
				a += width/2;
				}
				for (i=0;i<height/2;i++)
				{
				memcpy(buf+a,frame->data[2]+i*frame->linesize[2],width/2);
				a += width/2;
				}
				fwrite(frame_buf,1,frame_height*frame_width*3/2,yuvFile);
				delete[] frame_buf;
				delete[] buf;
				frame_buf = NULL;
				buf = NULL;
			}
			avcodec_free_frame(&frame);
		}
	}
	fclose(yuvFile);
	delete video_pkt;