The Umbrellas of Cherbourg (1964)

The 5.1 mix on both the StudioCanal and Criterion discs differs from all 5.1 mixes available on the older releases (including the 2.0 on the Japanese Happinet blu-ray of the old restoration), and is certainly an improvement. It's a new mix that was created in 2013.

The original mono mix has never been issued on home video, despite several DVDs claiming to carry it in the past – those tracks are all stereo, and were made for the earlier (1992) restoration of the film. The film's original mono mix has survived (as you'd expect), and was used--according to the new restoration notes--as a reference for the new remix.

The 5.1 track on the Criterion blu-ray (or 5.0 track, rather, as the LFE is empty) has some light noise reduction, while the StudioCanal 5.1 track has none. As with Playtime (a similar case), this additional NR was completely unnecessary.

The StudioCanal track can be synced with a -16350 ms delay. The 2.0 track on the StudioCanal blu-ray is a new stereo mixdown.

I assume the two audio tracks on the Arte Video blu-ray (which also carries the new restoration) sound the same as the StudioCanal tracks.