Issue: Add experimental threading support for parallel VMAF frame processing

Issue: Add experimental threading support for parallel VMAF frame processing: a task in LegoFlow-SWE (Harbor dataset). Currently, VMAF processes frames sequentially, which limits throughput when evaluating many video frames in batch. We need to introduce experimental multi‑threading support so…

The task

Currently, VMAF processes frames sequentially, which limits throughput when evaluating many video frames in batch. We need to introduce experimental multi‑threading support so that multiple frames can be processed concurrently, improving performance on multi‑core systems.

Part of Lego-X/LegoFlow-SWE.