"sounds playing over animation sequences - eg portal descending and switching on, the shutter door opening etc."
That should be no Problem, you can just use the Actionpart "Play sound" right before playing your Animation or in an Action on an Animationframe instead. And if your are using In-Scene-Videos for your Animations (with which I have no Experience though so far), placing the "Play sound"-Actionpart right before the Video should also work, and Videos can be set to continue the currently playing Sounds as well. (I guess the Sounds could be Part of the Video-File, but maybe that would allow for less Control or so.)
(EDIT: Ah yes, I just saw you are working ony an Animation-Video with the Sound.)
"there will also be continuous sounds from one scene to the other such as wind or ocean sounds."
Now, that is a Bit more of a Problem. By Default, Visionaire does not have that as a Feature, but you can use two simple Lines of Lua (an older Prototype of mine, never actually used it myself so far) to get it done.
(EDIT: The Following Solution only works if the Scene-Change is immediate, if there is no Fade-Effect set! If the Transition is set to directly fading to the next Scene (or Shift, I suppose), the Solution is not necessary at all, but with the Default-Fade it won't work at all. I might have to try and find a Fix for that.)
At the Beginning of a Scene:
Sound_Offset = getSoundProperty(SndCnt_Test, "offset")
At the End of a Scene:
SndCnt_Test = startSound("vispath:INSERTYOURFILEPATH.ogg", {flags=1, offset=Sound_Offset, loop=true})
Execute these two Scripts as shown in my Screenshots below, add these Actions to all the Scenes that should have one particular Sound playing, and the Sound will continue from the previous Scene once you enter a new one.
(Well, technically not "continue", but it will remember the Offset/Position of how far the Sound has been playing and continue from there on -- I have just tested this with two Scenes and have not had any Problems, it sounds like the Sound is just continuing.)
(EDIT: I should note, where it says "INSERTYOURFILEPATH", you must insert the Filepath relative to your Project-File -- so, if you have a Folder-Structure like "C://Neyyah/sounds/sound01.ogg" where the Project-File is inside the "Neyyah"-Folder, the String in the Code must be "vispath:sounds/sound01.ogg" -- the "vispath:" must stay.)
(On a Sidenote unrelated to this but to the Topic of Music, I forgot to mention that there is also an Action Part specifically for changing the currently playing Background-Music, so maybe that might also come in handy at some Point, if you ever need to change the Music due to an Event.)
"feels to me the sound and music is almost a complete world of its own when dealing with the development [...] Glad you are liking the project. Are you following Neyyah on the fb site[?]"
Yes, I am following the Project on Facebook (Christopher Summer) primarily because I'm a pretty big Riven-Fan -- I only follow with silent Likes, but after I saw that you are starting to record Sounds and intend to create the Music by yourself as well, I have started to think I really should comment for once or pm you just to say how much I appreciate it when someone creates pretty much everything for his Project by himself (well, I never wrote that on FB, so I am doing it here).
I have the same Philosophy (basically) and do the same with my own Project(s) -- I think that an Artist should try and create as much as he can by himself... especially if developing Sounds and Music (for this Game at Least) are "a complete world of its own" -- thumbs up for venturing into stranger Territories (like having to deal with Lua-Code, to get back on topic).
So, I hope these two Lines of Lua-Code will help you with the continuous Sound.
(I once prototyped them for the Developer behind "Noon's Journey - The Tideshell Keeper", but I'm afraid she left Visionaire before she could get the Code to work. I hope you have more Luck with it.
)