[BUG] Inaccurate export size prediction for the GIF format

[Vagventure]

Bug description
The estimated export file size calculation for the newly added GIF format is inaccurate. It dramatically underpredicts the final file size because GIFs do not utilize the same temporal compression algorithms as standard video containers (like MP4 or WebM), resulting in actual files that are significantly larger than estimated.

Steps to reproduce
Steps to reproduce the behavior:

1. Go to the export settings panel.
2. Upload any short video clip.
3. Select "GIF" from the Export Format dropdown menu.
4. See the "Estimated size" field display a low estimate, then export the file and observe that the actual output file size is much larger.

Expected behavior
The estimateExportSize utility should factor in a higher data-rate multiplier or a distinct calculation branch for the GIF format type so that the "Estimated size" label gives users an accurate expectation of the final asset size.

Actual behavior
The estimation logic uses the standard video bitrate parameters, causing it to display an inaccurately small estimated size for GIF exports.

Browser and OS info

• OS: Windows 11 / macOS 14
• Browser: Chrome / Firefox / Safari
• Version: Latest

Video format (if relevant)

• Input video format: MP4 / WebM
• Export preset used: Custom / Short Clip
• File size: Varied (GIF output is bloated compared to prediction)

Screenshots/screen recording

[Vagventure]

Hi @magic-peach, I'd like to work on this — contributing under GSSoC'26

[github-actions]

👋 Thanks for opening an issue, @Vagventure!

Our maintainers will review this shortly 🚀

Before you start working

• 📖 Read the CONTRIBUTING.md guide
• 💬 Wait for a maintainer to assign you the issue before starting work
• 🔍 Search for existing issues to avoid duplicates

For GSSoC'26 contributors

If you're contributing under GirlScript Summer of Code 2026, please mention it in your comment when requesting assignment:

"I'd like to work on this — contributing under GSSoC'26"

Architecture notes

Reframe is a static Next.js app with output: "export". Key points:

• All video processing uses FFmpeg.wasm (client-side, no server)
• headers() in next.config.ts won't work — use vercel.json instead
• not-found.tsx requires public/404.html + vercel.json routes config

Happy contributing! ⭐ Star the repo if you find it useful!

[Vagventure]

/assign

[github-actions]

Hey @Vagventure, this issue has been assigned to you! 🎉 Please make progress within 5 days or it will be automatically unassigned due to inactivity.

[Vagventure]

Hi @magic-peach , I've fixed this issue under GSSoC'26, please take a look.