[Feature]: Add custom audio format validation checks in file uploader

[knoxiboy]

Feature description
The video editor allows loading files but lacks validation checks for custom audio track codecs, leading to player crashes when users load unsupported formats.

Proposed solution

1. Add custom media type format checks to the file input controller.
2. Validate files on selection and return clear warnings to the user if the codec is unsupported before uploading.

---

/assign
Hi! @magic-peach
I would like to work on this issue under GSSoC'26. Please assign this issue to me.

[github-actions]

👋 Thanks for opening an issue, @knoxiboy!

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!

[knoxiboy]

/assign

[github-actions]

Hey @knoxiboy, you already have 5 issues assigned to you. Please complete or unassign one before picking up more. 🙏

[knoxiboy]

/assign

[github-actions]

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

[github-actions]

Hey @knoxiboy, just a friendly reminder that this issue has had no activity for 2 days. Please leave an update or let us know if you need help! ⏰

[github-actions]

Hey @knoxiboy, final warning! ⚠️ This issue has had no activity for 4 days and will be automatically unassigned in 24 hours if there is no update.

[knoxiboy]

Hey @knoxiboy, final warning! ⚠️ This issue has had no activity for 4 days and will be automatically unassigned in 24 hours if there is no update.

I already created a pr for this issue

[github-actions]

This issue has been unassigned from @knoxiboy due to 5 days of inactivity and is open for anyone to pick up — comment /assign to claim it!

[knoxiboy]

/assign

[github-actions]

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