video is none when using get_clip

[Physical-Chemist]

I loaded the encoded video, some clips gave None.

encoded_vid = pytorchvideo.data.encoded_video.EncodedVideo.from_path('1.avi')

inp_imgs = encoded_vid.get_clip(
    9 - 1/2.0, # start second
    10 + 1/2.0  # end second
)
inp_imgs

it shows:
{'video': None, 'audio': None}

then I tried another clip

inp_imgs = encoded_vid.get_clip(
    90 - 1/2.0, # start second
    100 + 1/2.0  # end second
)
inp_imgs

it shows:

{'video': tensor([[[[ 60.,  60.,  60.,  ..., 223., 223., 223.],
           [ 60.,  60.,  60.,  ..., 223., 223., 223.],
           [ 60.,  60.,  60.,  ..., 223., 223., 223.],
           ...,
           [ 99., 100., 101.,  ..., 223., 223., 223.],
           [ 99., 100., 101.,  ..., 223., 223., 223.],
           [ 99., 100., 101.,  ..., 223., 223., 223.]],
 
          [[ 60.,  60.,  60.,  ..., 226., 226., 226.],
           [ 60.,  60.,  60.,  ..., 226., 226., 226.],
           [ 60.,  60.,  60.,  ..., 226., 226., 226.],
           ...,
           [100., 101., 103.,  ..., 223., 223., 223.],
           [100., 101., 103.,  ..., 223., 223., 223.],
           [100., 101., 103.,  ..., 223., 223., 223.]],
 
          [[ 60.,  60.,  60.,  ..., 226., 226., 226.],
           [ 60.,  60.,  60.,  ..., 226., 226., 226.],
           [ 60.,  60.,  60.,  ..., 226., 226., 226.],
           ...,
           [103., 103., 103.,  ..., 223., 223., 223.],
           [103., 103., 103.,  ..., 223., 223., 223.],
           [103., 103., 103.,  ..., 223., 223., 223.]],
 
          ...,

I also loaded other videos with other format (.mp4 etc.), it has similar issue.
Can I get some help, pls?