Pad to Size instead of center crop

[Haydnspass]

Currently we crop a frame by default to multitudes of 8 so that we can forward it through the model. Change this to a less destructive pad to size, by padding until it reaches a multitude of 8.

Idea:

tar_size = ceil(actual_size / 8) * 8
pad_to_size(tensor, tar_size)

Resources:
https://pytorch.org/docs/stable/generated/torch.nn.utils.rnn.pad_sequence.html
Use pad_sequence put an artificial tensor of target size in and only return the input tensor.

[Haydnspass]

7b5f93c