in sam2/sam2_video_predictor.py [0:0]
def _get_maskmem_pos_enc(self, inference_state, current_out):
"""
`maskmem_pos_enc` is the same across frames and objects, so we cache it as
a constant in the inference session to reduce session storage size.
"""
model_constants = inference_state["constants"]
# "out_maskmem_pos_enc" should be either a list of tensors or None
out_maskmem_pos_enc = current_out["maskmem_pos_enc"]
if out_maskmem_pos_enc is not None:
if "maskmem_pos_enc" not in model_constants:
assert isinstance(out_maskmem_pos_enc, list)
# only take the slice for one object, since it's same across objects
maskmem_pos_enc = [x[0:1].clone() for x in out_maskmem_pos_enc]
model_constants["maskmem_pos_enc"] = maskmem_pos_enc
else:
maskmem_pos_enc = model_constants["maskmem_pos_enc"]
# expand the cached maskmem_pos_enc to the actual batch size
batch_size = out_maskmem_pos_enc[0].size(0)
expanded_maskmem_pos_enc = [
x.expand(batch_size, -1, -1, -1) for x in maskmem_pos_enc
]
else:
expanded_maskmem_pos_enc = None
return expanded_maskmem_pos_enc