SportSkills: Physical Skill Learning from Sports Instructional Videos

Current large-scale video datasets focus on general human activity, but lack depth of coverage on fine-grained activities needed to address physical skill learning. We introduce SportSkills, the first large-scale sports dataset geared towards physical skill learning with in-the-wild video. SportSkills has more than 360k instructional videos containing more than 630k visual demonstrations paired with instructional narrations explaining the know-how behind the actions from 55 varied sports. Through a suite of experiments, we show that SportSkills unlocks the ability to understand fine-grained differences between physical actions. Our representation achieves gains of up to 4x with the same model trained on traditional activity-centric datasets. Crucially, building on SportSkills, we introduce the first large-scale task formulation of mistake-conditioned instructional video retrieval, bridging representation learning and actionable feedback generation (e.g., "here's my execution of a skill; which video clip should I watch to improve it?"). Formal evaluations by professional coaches show our retrieval approach significantly advances the ability of video models to personalize visual instructions for a user query.

Stitch-a-Recipe: Video Demonstration from Multistep Descriptions

When obtaining visual illustrations from text descriptions, today's methods take a description with-a single text context caption, or an action description-and retrieve or generate the matching visual context. However, prior work does not permit visual illustration of multistep descriptions, e.g. a cooking recipe composed of multiple steps. Furthermore, simply handling each step description in isolation would result in an incoherent demonstration. We propose Stitch-a-Recipe, a novel retrieval-based method to assemble a video demonstration from a multistep description. The resulting video contains clips, possibly from different sources, that accurately reflect all the step descriptions, while being visually coherent. We formulate a training pipeline that creates large-scale weakly supervised data containing diverse and novel recipes and injects hard negatives that promote both correctness and coherence. Validated on in-the-wild instructional videos, Stitch-a-Recipe achieves state-of-the-art performance, with quantitative gains up to 24% as well as dramatic wins in a human preference study.