Media Converter

How to Use the Media Converter

Upload one supported video, pick an allowed output format for that input, convert locally with ffmpeg.wasm, then preview and download.

1. Upload a supported video — one MP4, MOV, MKV, AVI, or WebM file up to 100 MB.
2. Review the detected format — check filename, size, duration, and resolution when available, and preview the source.
3. Select output format — only conversions supported for your input are listed (same-format conversion is not allowed).
4. Click Convert and monitor progress — you can cancel if needed.
5. Preview the converted video, then download it or choose Convert Another.

Methodology & unified media pipeline

The media converter provides a unified pipeline for both visual and auditory media formats, dynamically selecting native canvas APIs for raster graphics and WebAssembly FFmpeg pipelines for audio/video streams.

File signatures (magic bytes) are inspected to verify actual container formats regardless of file extension tampering.

Worked media extraction example

• Input: MP4 conference webinar recording (250 MB, 1080p with stereo audio track).
• Target task: Extract audio track as standalone MP3 for on-the-go podcast listening.
• Process: Demuxer isolates the audio stream, skips video frame decoding, and encodes the audio track at 128 kbps.
• Output: 28 MB MP3 audio file ready in ~8 seconds without cloud upload.

Remux vs re-encode

Compatible remuxes (such as many MP4 ↔ MOV and MP4 → MKV conversions) copy streams when possible so resolution, frame rate, and audio channels stay the same. Other pairs re-encode with lossy codecs — quality never improves beyond the source.

Privacy

Video is processed locally with ffmpeg.wasm. Files are not uploaded to ToolsLibrary servers. Converter history, if enabled, stores filenames and format metadata only — never video Blob or ArrayBuffer content.

Limitations

One video up to 100 MB. Only matrix-listed pairs are supported. No resolution, bitrate, crop, trim, or audio-extraction controls. Unsupported codecs or low-memory devices can fail. Re-encoding can reduce quality.

FAQ

What formats does the Media Converter support?

Inputs: MP4, MOV, MKV, AVI, and WebM. Outputs depend on the input. The supported pairs are MP4 to MOV, MOV to MP4, MKV to MP4, AVI to MP4, WebM to MP4, MP4 to WebM, MP4 to AVI, and MP4 to MKV.

Can I convert MP4 to MOV or MOV to MP4?

Yes. Upload an MP4 and choose MOV, or upload a MOV and choose MP4. Compatible streams are remuxed when possible so resolution and frame rate stay the same.

Can I convert MKV to MP4?

Yes. Upload an MKV file and select MP4. The browser re-encodes to H.264 + AAC for broad MP4 compatibility.

Can I convert WebM or AVI to MP4?

Yes. WebM to MP4 and AVI to MP4 are supported. You can also convert MP4 to WebM, MP4 to AVI, and MP4 to MKV.

Are my media files uploaded to an external server?

No. Media files (both audio tracks and video streams) are processed entirely inside your browser sandbox using WebAssembly (ffmpeg.wasm). Your clips, audio recordings, and video containers remain on your local device and are not uploaded to ToolsLibrary servers.

Does converting improve video quality?

No. Remuxing keeps the same encoded streams. Re-encoding to another format can reduce quality and never improves it beyond the source.

Can I use this on mobile?

Yes on supported mobile browsers, but conversion may be slow or fail on low-memory devices. Keep files smaller when possible.

Can I extract audio or change resolution?

Not in this MVP. There are no resolution, frame-rate, bitrate, crop, trim, or audio-extraction controls. Use related converters for audio-only workflows or Video Converter when you need resolution presets.

Why did conversion fail?

The file may be empty, corrupted, use an unsupported codec, exceed the size limit, or be too large for this browser's memory. Try a shorter clip or a different source file.