f0s_to_jams is not compliant with pitch_contour namespace

[lostanlen]

The function jams_utils.f0s_to_jams produces a jam object whose Annotation is marked as pitch_contour. However, this Annotation is not compliant with the official pitch_contour namespace of JAMS. The consequence is that orchset Tracks cannot be exported to JAMS.

Minimal non-working example:

from mirdata import orchset

X = orchset.load()
keys = list(X.keys())
key = keys[0]
jam = X[key].to_jams()
jam.validate()

Result:

---------------------------------------------------------------------------
ValidationError                           Traceback (most recent call last)
~/miniconda3/lib/python3.7/site-packages/jams/core.py in validate(self, strict)
   1807         try:
-> 1808             schema.VALIDATOR.validate(self.__json_light__, schema.JAMS_SCHEMA)
   1809 

~/miniconda3/lib/python3.7/site-packages/jsonschema/validators.py in validate(self, *args, **kwargs)
    352             for error in self.iter_errors(*args, **kwargs):
--> 353                 raise error
    354 

ValidationError: None is not of type 'number'

Failed validating 'type' in schema['properties']['file_metadata']['properties']['duration']:
    {'minimum': 0.0, 'type': 'number'}

On instance['file_metadata']['duration']:
    None

During handling of the above exception, another exception occurred:

SchemaError                               Traceback (most recent call last)
<ipython-input-2-dbd09b7b0fbe> in <module>
----> 1 jam.validate()

~/miniconda3/lib/python3.7/site-packages/jams/core.py in validate(self, strict)
   1821         except jsonschema.ValidationError as invalid:
   1822             if strict:
-> 1823                 raise SchemaError(str(invalid))
   1824             else:
   1825                 warnings.warn(str(invalid))

SchemaError: None is not of type 'number'

Failed validating 'type' in schema['properties']['file_metadata']['properties']['duration']:
    {'minimum': 0.0, 'type': 'number'}

On instance['file_metadata']['duration']:
    None

It appears that the values in the Annotation of f0s_to_jams are of type float, as they describe the frequency in Hertz.
However, pitch_contour values are supposed to be triplets: (index, frequency, voicing).
Note that voicing is boolean ... this is pre-Bittner and Bosch ISMIR 2019 ;)