"Too high video bit rate"

A group of students ran into an issue yesterday when burning their final multi-audio layer DVD for their Audio Post Production coursework. The brief is for the students to create a 3 minute soundtrack for some original or found footage but there must be three audio layers: stereo mix, stereo mix with commentary and 5.1 ac3 mix. For some reason the DVD project in DVD SP4 would not build and the error message "too high video bit rate" kept on appearing. Firstly I tried lowering the maximum bit rate within the encoder section of the preferences window; no joy. Next I tried compressing their video file into an m2v file in "COMPRESSOR" so that no transcoding was required within DVD SP4; still no joy. Next I tried converting their audio files into AIFF 48kHz 16 bit files (even though they were already in this format); still no joy.

Finally I tried building the disc with just the main stereo audio layer - hooray, success! However, this was no good since they need to have three audio layers to accompany the video stream? I next tried just the main stereo stream with the 5.1 ac3 stream - hooray, even more success! What about just adding the main stereo and stereo with commentary layers I hear you ask? No joy! Therefor, for some reason DVD SP4 would not build the DVD when it had two uncompressed audio layers even though I have done this and demo'd this many times successfully?

Any how, the only option was for me to convert the uncompressed stereo with commentary file into 2.0 ac3 (using the Dolby Digital Professional 2.0 preset within COMPRESSOR) and then to re-import this into DVD SP4. Now, with the uncompressed stereo mix on layer 1, ac3 stereo with commentary on layer 2 and 5.1 ac3 mix on layer 3, everything worked fine. This is slightly frustrating however since I wanted the students to submit uncompressed versions of their two stereo mixes. Very strange?