Vidio OpenCVReader failing on some videos

[jonahpearl]

This issue may be fairly specific to Tim's 6cam rig setup in our lab but here it is anyways — the OpenCVReader from vidio can't figure out how many frames those videos have, and that causes a weird failure in the grid movie code.

MRE:

from vidio.read import OpenCVReader

p = # path to video from tim's 6cam rig 
reader = OpenCVReader(p);
print(reader.nframes)  # some large negative integer
frame = reader.read(0)  # error due to this line in vidio: https://github.com/jbohnslav/vidio/blob/df2be96f63a06fa009d087fa81982fb8e2d27ec4/vidio/read.py#L39

# manual fix that should work unless you try to iterate through the reader object
reader.nframes = 1e6  # or some other large number
frame = reader.read(0)  # works

Suggested fix: use check_video_paths to return the open and, if needed, manually fixed OpenCVReader objects. So something like

readers = {}
for path in video_paths:
  reader = OpenCVReader(path)
  try:
      reader[0]
  except ValueError:
      reader.nframes = 1e7
  except:
      unreadable_videos.append(path)
      continue
  readers[path] = reader

But also there's a chance this introduces weird bugs into the video reading code, so this should probably just be a local fix for anyone in our lab who needs it.