Introduction
Tennis players often find themselves in a feedback vacuum. Without a coach physically present, pinpointing what’s wrong with a stroke becomes a guessing game. This gap in immediate, stroke-specific guidance is a silent killer of progress, leaving players to rely on sporadic coaching sessions or self-diagnosis, which often misses the mark. The problem isn’t just about lack of access to coaches—it’s about the inability to see and correct subtle technique flaws in real time.
Enter Rallylens, a web app born out of personal frustration. As a student and tennis player, I built this tool to address the disconnect between practice and feedback. It uses video analysis powered by AI to break down uploaded tennis videos frame by frame, identify stroke types (forehand, backhand, serve), and compare them against ideal technique benchmarks. The system doesn’t just flag errors—it explains them. For instance, if a backhand stroke shows an inconsistent racket angle, the feedback highlights this deviation and suggests adjustments, focusing on mechanics like wrist rotation or body alignment.
The Mechanism Behind the Feedback
Rallylens operates through a multi-step process that mimics a coach’s eye but with the precision of machine learning:
