Darpan 🪞

Darpan (Sanskrit: "Mirror") - A state-of-the-art, zero-latency, purely peer-to-peer WebRTC video calling application.

Darpan is designed to provide the absolute highest mathematical fidelity for 1-on-1 video communication. By bypassing centralized Selective Forwarding Units (SFUs) used by enterprise tools (Zoom, Meet), Darpan achieves true end-to-end encryption and sub-50ms latency.

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🚀 Key Features

• Zero-Latency P2P Architecture: Direct IP-to-IP tunnels via RTCPeerConnection.
• State-of-the-Art AV1/VP9 Codecs: Explicitly enforces next-generation video codecs via SDP parameter injection, guaranteeing vastly superior image quality over legacy VP8/H264 at identical bitrates.
• Studio-Grade Audio: Forces 48kHz Stereo Opus encoding alongside hardware-level Acoustic Echo Cancellation (AEC) and Noise Suppression.
• WebGL GPU Post-Processing: Offloads visual enhancements to the GPU. Darpan runs a real-time 3x3 Convolution Matrix (Unsharp Mask) fragment shader alongside a contrast/gamma curve to artificially sharpen blurry webcams.
• Live Telemetry: Real-time polling of WebRTC network stats (Upload/Download Mbps) right in the UI.

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📐 Architecture Overview

Darpan relies on PeerJS purely for initial STUN/TURN signaling (handshaking). Once the connection is established, the server is completely removed from the loop.

sequenceDiagram
    participant Caller (Peer A)
    participant PeerJS (Signaling)
    participant Receiver (Peer B)

    Caller (Peer A)->>PeerJS (Signaling): Connect & Register ID
    Receiver (Peer B)->>PeerJS (Signaling): Connect & Register ID
    
    Note over Caller (Peer A),Receiver (Peer B): Handshake Phase
    Caller (Peer A)->>PeerJS (Signaling): Offer (I want to call B)
    PeerJS (Signaling)->>Receiver (Peer B): Forward Offer
    Receiver (Peer B)->>PeerJS (Signaling): Answer
    PeerJS (Signaling)->>Caller (Peer A): Forward Answer
    
    Note over Caller (Peer A),Receiver (Peer B): Secure P2P Tunnel Established
    Caller (Peer A)-)Receiver (Peer B): DTLS/SRTP Encrypted AV1/Opus Media Stream
    Receiver (Peer B)-)Caller (Peer A): DTLS/SRTP Encrypted AV1/Opus Media Stream

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🛠️ Codebase Structure

To make this codebase easily understandable for new developers, it is strictly separated by concern:

File	Purpose
index.html	The core layout. Implements a minimalist, glassmorphic UI.
style.css	Handles all aesthetics, CSS variables for theming, and responsive layouts.
app.js	The monolithic logic controller. Handles getUserMedia, PeerJS signaling, transceiver codec injection, and device enumeration.
upscaler.js	The WebGL rendering engine. Intercepts the HTML <video> stream and pipes it through a custom GPU fragment shader for sharpening.
debug.js	Diagnostics tool. Monitors ICE states and outputs to the console.
stress.js	Synthetic CPU/Memory load generator for testing application resilience.

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💻 Local Development

Because Darpan uses native browser APIs (navigator.mediaDevices), it must be served over localhost or a secure https context. It will not work if you simply open the HTML file from the file explorer.

Prerequisites

• Node.js installed.

Setup

1. Clone the repository:

   git clone https://github.com/sagnikrout/Video_Call.git
   cd Video_Call

2. Serve the directory locally (using any HTTP server):

   npx serve .

3. Open http://localhost:3000 in your browser.

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🧪 Testing

Darpan uses Playwright for headless E2E testing. We use the --use-fake-ui-for-media-stream and --use-fake-device-for-media-stream chromium flags to mock camera hardware in CI/CD.

npm install
npx playwright test

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📜 License

MIT License - Free to use, modify, and deploy.