Another thing I thought is the following: as it seems there is no proper Dolby Surround/Dolby ProLogic software encoder, it is still possible to capture the analog out of a Dolby ProLogic hardware decoder, and then use the captured sountrack to build up a discrete soundtrack for a project, using low compressed AC3/DTS...
A "simple" uncompressed PCM is the most logical way - even a low compressed AC3 should retain the Dolby Surround matrixed signal - but I wonder if the former technique will result in better (or different) audio, as the Dolby ProLogic (hardware) decoder should first convert analog matrixed stereo signal to digital, then decode it to four discrete channel, and convert back to analog, while a Dolby Digital simply "disassemble" the digital stream, so no ADC is involved...
It will be interesting to make some tests, as there are certain Dolby Surround tracks that are better than their discrete counterparts...
Opinions?