| """Frame gather / scatter-add for replay over arbitrary selected frame indices. | |
| The stride-4 sampler selects interleaved pixel frames; the replay must (a) gather | |
| those frames into a 16-frame clip and (b) scatter the clip's pixel gradient back | |
| into the full 81-frame buffer, **accumulating** when a frame is selected by | |
| multiple clips / crops / encoders (spec section 11.3). | |
| """ | |
| from __future__ import annotations | |
| import torch | |
| # Re-export the canonical implementations from the sampler module so there is a | |
| # single source of truth for the gather/scatter rule. | |
| from video_fd.samplers.stride4_clip_sampler import gather_frames, scatter_add_frames | |
| __all__ = ["gather_frames", "scatter_add_frames", "new_frame_grad_buffer"] | |
| def new_frame_grad_buffer(video: torch.Tensor) -> torch.Tensor: | |
| """Zero gradient buffer matching a ``[B, T, 3, H, W]`` video (float32).""" | |
| return torch.zeros_like(video, dtype=torch.float32) | |