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Building a React Native Video Processor with FFmpeg

How I built an open-source React Native library for video processing using FFmpeg-kit, handling compression, trimming, and format conversion.

React NativeFFmpegOpen Source

Video processing in mobile apps has always been challenging. Native solutions are complex, and cross-platform options were limited. That's why I built react-native-video-processor.

The Problem

When building mobile apps, I often needed to:

  • Compress videos before uploading
  • Trim clips to specific durations
  • Convert between formats
  • Extract thumbnails
Existing solutions were either too heavy, poorly maintained, or didn't work well on both iOS and Android.

The Solution

I chose FFmpeg-kit as the foundation because it's the most powerful and well-maintained FFmpeg wrapper for mobile. The library provides a simple API:

import { VideoProcessor } from 'react-native-video-processor';

// Compress a video const result = await VideoProcessor.compress(videoPath, {   quality: 'medium',   maxWidth: 1280,   maxHeight: 720, });


// Trim a video const trimmed = await VideoProcessor.trim(videoPath, {   startTime: 0,   endTime: 30, });

Key Challenges

1. Memory Management

Video processing is memory-intensive. On older devices, processing large videos could crash the app. I implemented chunked processing and added memory warnings.

2. Cross-Platform Consistency

iOS and Android handle video codecs differently. H.264 works everywhere, but hardware acceleration varies. The library abstracts these differences.

3. Progress Tracking

FFmpeg outputs progress to stderr in a specific format. Parsing this reliably across different video lengths and formats required careful regex work.

Results

The library now has over 500 stars on GitHub and is used in production apps. The most satisfying part is seeing issues where developers share how it solved their problems.

Lessons Learned

  • Start with a clear, focused API
  • Write tests for edge cases (corrupted files, unusual formats)
  • Document everything with real examples
  • Respond to issues quickly - it builds community trust

    • Open source is rewarding. You solve your own problem and help others along the way.