In order to put 2hr video into DVD (4.7G), the bitrate should set to about 4Mbps, if set to 8Mbps, it just may contain about 60minutes video.

Many document say that 4.7G disc may contain about 2hr high quality video. But it doest mention which bitrate to use.

The quality should have difference between 4Mbps and 8Mbps.

So which bitrate should I choose?