Mehfil – Real-Time Synchronized Multi-Device Music Player

Mehfil is a real-time synchronized multi-device music player that turns multiple smartphones into one coordinated sound system. Instead of relying on a single speaker, users can connect several phones and play the same song together, creating a shared music experience for college parties, small gatherings, and social events.

Imagine playing the same song on five phones. If each phone starts at a slightly different time, the music sounds like an echo. Mehfil addresses this problem by coordinating playback across connected devices using clock synchronization, scheduled playback, and continuous timing correction.

The application uses a laptop as the host and controller, while smartphones join the music room through a QR code using their web browsers. No dedicated mobile application or user account is required. The host can manage the music queue, upload audio files, select synchronization modes, and monitor the connected devices.

Mehfil uses a real-time communication system to exchange timing information between the host and connected phones. Each phone estimates how its clock differs from the server's clock. When playback begins, the server schedules a future start time rather than simply telling every phone to play immediately. This gives the devices time to prepare before playback starts.

The application also checks playback positions periodically and makes small timing adjustments to reduce synchronization drift. For more advanced synchronization, Mehfil provides speaker-delay calibration. A phone plays a short test sound, the laptop's microphone records it, and digital signal processing techniques help estimate the delay between the sound being played and received.

Mehfil includes an interactive Antakshari mode, where teams can play a music-based word game, and a Light Mode, where connected phones flash along with the beat. Its evaluation dashboard provides tools for measuring synchronization differences, comparing playback methods, and analyzing device timing.

The project combines full-stack web development, real-time communication, audio processing, distributed-system concepts, and interactive user interface design. It is suitable for students interested in understanding how independent devices can coordinate their actions over a network.