Mapping to create list of candidates for sound categories

[edufonseca]

Currently, lists of candidates for sound categories are the result of a tag-matching process. Freesound tags were manually assigned to the target categories, which were automatically populated with the Freesound clips presenting the aforementioned tags.

This process presents certain limitations that may (or not) be improved:

• we have some categories with very few annotations.
• we could have higher precision (currently, around 40% of the annotations are not validated as Present, which wastes annotation effort)
• perhaps we could also have higher recall (make sure we don't leave Freesound clips out, and all possible annotations are assigned to a clip).

How to improve the mapping?
For instance, utilizing content-based techniques using the annotations already validated as Present. In this respect, @soramas has done some tests and @xavierfav has some proposals.

When the mapping to use is decided (either the current one or another), it will be the starting point for other tasks, eg, #26 . The mapping will be able to populate categories to some extent, with some estimated precision. This will have to be taken into account to determine an initial subset of annotations to focus on for the FSD 1st release.