I am trying to edit home movies that I have copied from VHS format to DVD. I used the Pioneer DVR RT300. But the file format seems to be non-standard. Does anyone know where I can get software to edit that format, or software to translate it into a more standard format?

You should be able to edit the content from the DVD your Pioneer writes in pretty much the same way as with content ripped from another DVD. As your DVD recorder does not put CSS copy protection on the DVD it writes, you should be able to copy its content directly to the PC and work from it directly.

While the content on the DVD is standard MPEG2, you will need an editor that can handle VOB files in order to perform editing. My favourite is mpg2cut2, which allows one to open a recording, select the start & end, extract this section and store it as a regular MPEG2 file. The tool can also join recordings of the same configuration and quality. This can be downloaded from here. If you use this, be sure to download the "LibMMD + MpaLib" DLL's also (further down their page) as this will let you preview content through the editor.

On the other hand, if you are interested in converting the content to another codec, such as DivX, XviD, etc. you will need an editor that can handle MPEG2 files, since most encoders will not accept MPEG2 files as a source. A few examples include VirtualDubMod, FlaskMPEG, etc.

To discuss about video editing software or encoding content from DVD to DivX, XviD, etc. this would be best done in the Video Edit Software forum.