Please help me how to maintain the video resolution when burning the video file using Nero

I was trying to burn an AVI file using Nero but the resolution has change after adding the file. The said avi file is a converted mkv format with original resolution 640x480. When I added it to the Nero the resolution has changed to 352x240 and the subtitle became too small. Please help how to maintain the resolution and the size of the subtitle when burning the file to vcd.

Thanks a lot..