Those of us to which to have a larger selection of choices should add our own field and customize it and not beg for this locked down field to be changed to popular requests.
I hope you didn't get this idea from me. The developers have invited requests for additions. I just think it's pointless to bother. Why would you want your personal classification system to depend on JRiver's approval of every term you may want to use?
Is there a way for my new field .Media Sub Type to take the default value of the original field Media Sub Type but still allow it to be change to one of a predetermined list?
I think you should consider using the approach I suggested. That is, use an expression field [Media Sub Type.x] to combine [Media Sub Type] and [Media Sub Type (custom)]. Then use that expression field for what you would otherwise use [Media Sub Type] for (i.e., configuring views, etc.). Let the program/Carnac do whatever it wants to do in tagging [Media Sub Type] (which, BTW, includes tagging podcasts imported by the podcast system as 'Podcast'). Use the [Media Sub Type.x] expression to set values to those already set in [Media Sub Type] or to something different based on [Filename] (e.g., the folder the file is in). [Media Sub Type (custom)] would be a "manual override" field—for cases where there is no basis for setting the value automatically. Those would probably just be for exceptions you don't want to bother dealing with in the expression.
It may sound ominous, but the basic logic of the classification expression would be straightforward...
If(IsEmpty([Media Sub Type (custom)]),
{series of nested If-statements to get value from [Filename], else [Media Sub Type]},
[Media Sub Type (custom)])
That middle bit is necessarily vague because the details depend entirely on your file organization and the media sub type values you want to end up with. It will be as simple or as complicated as you want to make it. In the end, it can set a value for
all files automatically, and you'll be able to override any result by setting [Media Sub Type (custom)].
There are many advantages to this approach. Unlike
Auto-Import rules, it will adapt to files being reclassified by moving them to a different folder. There will be a clear separation of functions: The program will continue to use [Media Sub Type] values to determine various things, and you may need to change such values if Carnac has failed to do so correctly. Or, you might, for example, use an
Auto-Import rule to set it to 'Movie' for all files from your trailer folder—so the meta data import will be available. [Media Sub Type.x] will determine how files are handled in views. It would, to use the same example, set a value of 'Trailer' for your trailer files—to distinguish them from 'Movie' in your views. Although the [Media Sub Type.x] expression may be a long one, if used effectively, it can be the
one place to look to determine how all your video media is classified in views.
My suggestion is based on the premise a 'Media Sub Type' set according to the user's desired classification system is needed. That's only the case if the user insists it be so. Although I like the idea of my suggestion, I don't use it myself. I've always treated [Media Sub Type] as an internal field, using it only when convenient and 'safe' to do so. In configuring a view, I'll more often refer to [Filename] or some other existing data directly to determine what is to be displayed. Which approach makes the most sense depends on the circumstances (e.g., how well-organized the file system is) and personal preference.