If you want a playable DVD, you are stuck with MPEG2 compression (I believe you could also use MPEG1 but the quality would be much poorer so no point considering it). The only way to reduce the file size is to compress more, so the quality will definitely get worse. How much worse depends on the final bit rate and the encoder you use to do the compression.

If you have a good software encoder like Procoder, you can select multi-pass VBR encoding which will help to minimise the quality loss even at low bit rates. However you have to be realistic - even then there will be noticeable degradation.

Another consideration is the audio compression. If your existing audio happens to be uncompressed, you can squeeze it much smaller using Dolby stereo encoding. This by itself could give you the file size reduction you need, but if the audio is already encoded you are probably out of luck.

Maybe if you could provide some info on the exisitng 5GB MPEG file someone on the forum could give you more specific advice?

Richard Hunter