`LABLoader` raise ValueError("`path` must contain the {uri} placeholder.") even if the placeholder is configured correctly

[alephpi]

Part of my configuration:

Databases:
  # tell pyannote.database where to find AMI wav files.
  # {uri} is a placeholder for the session name (eg. ES2004c).
  # you might need to update this line to fit your own setup.
  AMI: amicorpus/{uri}/audio/{uri}.Mix-Headset.wav
  AMI-SDM: amicorpus/{uri}/audio/{uri}.Array1-01.wav

Protocols:

  AMI-SDM:
    SpeakerDiarization:
      only_words:
        train:
            uri: ../lists/train.meetings.txt
            annotation: ../only_words/rttms/train/{uri}.rttm
            annotated: ../uems/train/{uri}.uem
            lab: ../only_words/labs/train/{uri}.lab
        development:
            uri: ../lists/dev.meetings.txt
            annotation: ../only_words/rttms/dev/{uri}.rttm
            annotated: ../uems/dev/{uri}.uem
            lab: ../only_words/labs/dev/{uri}.lab
        test:
            uri: ../lists/test.meetings.txt
            annotation: ../only_words/rttms/test/{uri}.rttm
            annotated: ../uems/test/{uri}.uem
            lab: ../only_words/labs/test/{uri}.lab

When I comment out these two lines, the program runs well and file['lab'] returns exactly an Annotation object https://github.com/pyannote/pyannote-database/blob/da5794b4bef2e95e93659817799aff6a770366a9/pyannote/database/loader.py#L260-L261

Seems this sanity check is not working as expected. Also other loaders (e.g. RTTMLoader) don't have this line (I guess the logic should be similar).

[alephpi]

Another observation: load_rttm() returns a dict as {uri: annotation} while load_lab() returns simply annoation object, just wonder if this is a delibrate design as I see no reason for distinguishing the behaviour for similar functionalities.

[hbredin]

The difference between rttm and lab lies in the fact that

• lab format has no filename field, one lab file can therefore contain annotations for only one audio file. the uri must therefore be infered from the lab file name.
• rttm format has a filename field, one rttm file can therefore contain annotations for multiple audio file.

[alephpi]

Then what's the proper way to configure lab? Could you give me an example?