Mismatch between expelliarmus and metavision

[stevenabreu7]

I loaded the same .raw file from a prophesee camera (evt2 format) with expelliarmus and metavision and I get very different numpy arrays from it. Here is the code I used for expelliarmus:

from expelliarmus import Wizard
import numpy as np

wizard = Wizard(encoding="evt2", fpath="A1.raw")
arr = wizard.read()
np.save("A1.npy", arr)

And the code using prophesee's meta vision library:

from metavision_core.event_io import EventsIterator
import numpy as np

ev_it = EventsIterator("A1.raw")
arr = np.concatenate([ev for ev in ev_it])
np.save("A1.npy", arr)

Here is a histogram of the events over time for both approaches (for eight different data files, top is meta vision, bottom is expelliarmus):

Looking at the numpy data, I cannot easily see what went wrong. What's curious is that the first ~40 entries have timestamps <50, and then it jumps to a timestamp of >3e9.

Any idea what could have gone wrong there?

[fabrizio-ottati]

Uhm I think this is a bug inside expelliarmus, honestly. I will look into it immediately. Does it happen also for EVT3? I don't know if you have access to this kind of format.

[stevenabreu7]

Yeah unfortunately I don't have a EVT3 file available so I can't check. Thanks for looking into it so quickly!

[fabrizio-ottati]

Could you try with this EVT2 RAW file and see what you get? If you could pass me the resulting NPY file on Discord, I would be really grateful :) You can find the link in the README of the repository.