DVD videos have 720x480 resolution, so 704x480 is not HD video.

There could be a problem with MediaCoder or with the way your video is recorded.

Try some other audio/video converter. You can use freeware virtual dub or commercial Cucusoft Ultimate Video Converter, Nero Recode and many, many other programs.

If you decide to use commercial software, don't buy it right away. Test a free trial version first to make sure it works for youl.