1hew-ComfyUI-1hewNodes/web/docs/1hew_MaskBatchRange/en.md

Mask Batch Range - Sample masks by start and step

Node Purpose: Mask Batch Range samples masks from a batch using start_index, step, and num_frame. num_frame means the final number of masks to output. When num_frame = 0, it keeps sampling from start_index to the end using step. If start_index is out of range (≥ total), the output is an empty batch.

Inputs

Name	Port	Type	Default	Range	Description
mask	-	MASK	-	-	Input mask batch.
start_index	-	INT	0	0-8192	Starting frame index; if start_index ≥ total, returns empty.
step	-	INT	1	1-8192	Sampling stride. 1 means contiguous, 2 means take every other mask.
num_frame	-	INT	1	0-8192	Final number of masks to take. 0 means keep taking with step until the end.

Outputs

Name	Type	Description
mask	MASK	Sampled mask batch based on start/step settings, or empty when out-of-range.

Features

• Bounds-safe: returns empty when start_index ≥ total.
• Step sampling: starts at start_index and samples using step.
• To-end mode: when num_frame = 0, sampling continues until the final mask.
• Async slicing: performs slicing in a worker thread.
• Empty handling: returns an empty batch with matching dtype/device when needed.

Typical Usage

• Take the first N masks contiguously: start_index=0, step=1, num_frame=N.
• Sample every K masks from a point: start_index=S, step=K, num_frame=N.
• Sample from a point to the end: start_index=S, step=K, num_frame=0.

Notes & Tips

• Mirrors the behavior of Image Batch Range for mask tensors.
• If start_index ≥ total, output is empty.
• If num_frame > 0 and fewer masks are available, only the available masks are returned.
• When step = 1, behavior remains compatible with the old contiguous slice behavior.
• If total = 0, output is empty.