How to Convert a Video of a UI to Functioning Frontend, Backend and DB calls

TL;DR: Replay transforms UI screen recordings into fully functional frontend code, complete with backend API calls and database integration, using behavior-driven reconstruction powered by Gemini.

Stop Building UIs From Scratch: Reconstruct Them From Video#

We've all been there: staring at a design mockup, spending hours translating static images into interactive code. What if you could skip the tedious translation and jump straight to a working prototype? Screenshot-to-code tools offer a partial solution, but they only capture the visual surface. They miss the crucial element: user intent.

That's where Replay comes in. Replay is a video-to-code engine that analyzes user behavior in screen recordings to reconstruct functional UIs, complete with frontend components, backend API calls, and database interactions. By understanding what the user is trying to accomplish, not just what they see, Replay generates more accurate and useful code.

The Problem with Screenshot-to-Code#

Screenshot-to-code tools have limitations. They can generate basic HTML and CSS, but they struggle with:

• •Dynamic behavior: Handling user interactions like button clicks, form submissions, and data updates.
• •Backend integration: Connecting the UI to APIs and databases.
• •Multi-page applications: Reconstructing complex flows across multiple screens.

These tools treat the UI as a static image, ignoring the underlying logic and user intent.

Behavior-Driven Reconstruction: Replay's Secret Sauce#

Replay uses a novel approach called "Behavior-Driven Reconstruction." Instead of simply analyzing pixels, Replay analyzes the sequence of actions in a video recording. This allows Replay to infer the user's goals and generate code that reflects those goals.

Here's how it works:

1. •Video Analysis: Replay analyzes the video, identifying UI elements, user interactions (clicks, typing, scrolling), and page transitions.
2. •Intent Inference: Using Gemini, Replay infers the user's intent behind each action. For example, a user typing into a search bar likely intends to search for something.
3. •Code Generation: Replay generates frontend code (React, Vue, etc.), backend API calls (Node.js, Python, etc.), and database schemas (Supabase, PostgreSQL, etc.) based on the inferred intent.

Replay in Action: From Video to Working UI#

Let's walk through a practical example. Imagine you have a video recording of a user creating a new account on a web application. Here's how Replay can reconstruct the UI and backend logic:

Step 1: Upload the Video to Replay#

Simply upload the video file to the Replay platform. Replay supports various video formats (MP4, MOV, etc.).

Step 2: Replay Analyzes the Video#

Replay processes the video, identifying UI elements like input fields, buttons, and labels. It also detects user interactions, such as typing in the email field and clicking the "Create Account" button.

Step 3: Replay Generates the Frontend Code#

Replay generates React code for the account creation form:

typescript
// React component generated by Replay
import React, { useState } from 'react';

const CreateAccountForm = () => {
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');

  const handleSubmit = async (e) => {
    e.preventDefault();
    const response = await fetch('/api/create-account', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({ email, password }),
    });

    if (response.ok) {
      // Account created successfully
      alert('Account created!');
    } else {
      // Handle error
      alert('Error creating account');
    }
  };

  return (
    <form onSubmit={handleSubmit}>
      <div>
        <label htmlFor="email">Email:</label>
        <input
          type="email"
          id="email"
          value={email}
          onChange={(e) => setEmail(e.target.value)}
        />
      </div>
      <div>
        <label htmlFor="password">Password:</label>
        <input
          type="password"
          id="password"
          value={password}
          onChange={(e) => setPassword(e.target.value)}
        />
      </div>
      <button type="submit">Create Account</button>
    </form>
  );
};

export default CreateAccountForm;

Step 4: Replay Generates the Backend API#

Replay also generates a Node.js API endpoint to handle the account creation:

javascript
// Node.js API endpoint generated by Replay
const express = require('express');
const router = express.Router();
const { supabase } = require('./supabaseClient'); // Assuming Supabase integration

router.post('/create-account', async (req, res) => {
  const { email, password } = req.body;

  try {
    const { data, error } = await supabase.auth.signUp({
      email: email,
      password: password,
    });

    if (error) {
      console.error('Error creating account:', error);
      return res.status(500).json({ error: 'Failed to create account' });
    }

    console.log('Account created:', data);
    res.status(200).json({ message: 'Account created successfully' });
  } catch (error) {
    console.error('Unexpected error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

module.exports = router;

Step 5: Replay Generates the Supabase Schema#

Replay automatically creates the necessary tables and schemas in your Supabase database to store user data.

sql
-- Supabase schema generated by Replay
CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
  email VARCHAR(255) UNIQUE NOT NULL,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

-- Enable Realtime subscriptions
ALTER TABLE users ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Enable read access for all users" ON users FOR
SELECT USING (TRUE);

CREATE POLICY "Enable insert access for authenticated users" ON users FOR
INSERT WITH CHECK (auth.role() = 'authenticated');

💡 Pro Tip: Replay intelligently names variables and functions based on the context of the video, making the generated code more readable and maintainable.

Replay vs. the Alternatives#

Here's a comparison of Replay with other UI generation tools:

📝 Note: Replay is not intended to replace hand-crafted code entirely. It's a powerful tool for rapid prototyping, generating boilerplate code, and reverse engineering existing UIs.

Key Features of Replay#

Replay offers a range of features to streamline UI development:

• •Multi-page generation: Reconstruct entire application flows from a single video.
• •Supabase integration: Seamlessly connect your UI to a Supabase database.
• •Style injection: Apply custom styles to the generated UI.
• •Product Flow maps: Visualize user flows and identify areas for improvement.
• •Support for React, Vue, and Angular: Generate code for your preferred frontend framework.
• •Customizable Code Output: Fine-tune the generated code to match your team's coding standards.

⚠️ Warning: The accuracy of Replay's code generation depends on the quality of the input video. Clear, well-defined videos will produce the best results.

Real-World Use Cases#

Replay can be used in a variety of scenarios:

• •Rapid Prototyping: Quickly create a working prototype from a video recording of a design concept.
• •Reverse Engineering: Reconstruct the UI of an existing application from a screen recording.
• •Code Generation for Tutorials: Automatically generate code examples for tutorials and documentation.
• •Legacy Code Migration: Modernize legacy applications by reconstructing their UIs from video recordings.
• •User Testing Analysis: Analyze user behavior in video recordings to identify usability issues and generate code fixes.

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited usage. Paid plans are available for higher usage and advanced features.

How is Replay different from v0.dev?#

v0.dev generates UI components based on text prompts. Replay generates fully functional UIs (frontend, backend, database) from video recordings, capturing user behavior and intent. Replay focuses on reconstructing existing UIs or prototypes, while v0.dev focuses on generating new UIs from scratch.

What video formats does Replay support?#

Replay supports common video formats like MP4, MOV, AVI, and WebM.

What frontend frameworks does Replay support?#

Currently, Replay supports React, Vue, and Angular. Support for other frameworks is planned for the future.

How accurate is Replay's code generation?#

The accuracy of Replay's code generation depends on the quality of the input video and the complexity of the UI. In general, Replay can generate highly accurate code for well-defined UIs with clear user interactions.

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