MP4 to MKV — Format Comparison & Online Converter
Fast, instant MP4 to MKV conversion. No signup required. Just drop your .mp4 file and get .mkv in seconds.
Batch Settings
Generation loss — quality may degrade
MP4 uses lossy compression, and so does MKV. Converting means decoding and re-encoding — each cycle can permanently degrade quality. Convert from the original source file whenever possible.
Some metadata may not survive
Your MP4 file may contain MP4 atoms metadata. MKV has limited or no support for these metadata types. Location data (GPS), camera settings, and color profiles may be stripped during conversion.
Color depth reduction: 265-bit → 10-bit
MP4 stores up to 265 bits per channel, but MKV supports only 10 bits. You may notice banding in smooth gradients (like sky or skin tones) where subtle color transitions are lost.
What compression artifacts to expect
MKV lossy compression can produce codec-dependent. At the high quality settings CocoConvert uses by default, these are usually invisible to the eye. Lower quality settings trade visual fidelity for smaller file sizes.
Le MP4 s'est imposé partout — sur les téléphones, les plateformes de streaming, les clés USB qu'on passe de main en main. Mais il a ses limites : une seule piste audio, pas de sous-titres intégrés, des options de compression restreintes. Le MKV, lui, est un conteneur ouvert qui accepte plusieurs langues, plusieurs flux de sous-titres et des codecs variés sans rechigner. Que vous prépariez un montage final, que vous archivisez des rushes ou que vous souhaitiez simplement conserver une copie fidèle d'un fichier sans le réencoder, la conversion vers MKV offre une souplesse que le MP4 ne peut pas toujours garantir. Ici, la conversion se fait directement, sans perte de qualité inutile.
- Archivage de documentaires institutionnels pour médiathèques publiques (BnF, Bibliothèque et Archives nationales du Québec)
- Intégration de sous-titres multilingues dans des productions académiques ou des thèses audiovisuelles
- Livraison de fichiers vidéo pour agences de design et studios de post-production (Paris, Montréal, Genève)
En France et en Belgique, plusieurs diffuseurs publics et institutions culturelles exigent le MKV comme format de dépôt pour les œuvres audiovisuelles subventionnées, notamment en raison de sa compatibilité avec les flux de sous-titres DVB. Au Québec, l'Office québécois de la langue française recommande des formats ouverts pour la conservation numérique des contenus en français.
About MP4 to MKV Conversion
MP4 (introduced 2001) and MKV (introduced 2002) are both video formats, but they differ in important ways. MP4 (MPEG-4 Part 14) is the universal video container supporting H.264/H.265 codecs — plays on virtually every device. MKV (Matroska) is an open container supporting virtually any codec, multiple audio tracks, and subtitles.
Full Name: MP4 uses MPEG-4 Part 14, while MKV uses Matroska Video. Compression: MP4 uses Lossy, while MKV uses Lossy. Color Depth: MP4 uses 8-bit (H.264) or 10-bit (H.265/AV1), while MKV uses 8–10 bits (codec dependent).
When you convert MP4 to MKV, the goal is to convert between formats quickly. MP4 uses lossy compression, and so does MKV. Converting means decoding and re-encoding — each cycle can permanently degrade quality. Convert from the original source file whenever possible. Understanding these technical differences helps you choose the right format for your workflow.
Your MP4 file is decoded and re-encoded as MKV. The conversion involves 4 steps: (1) your mp4 file is uploaded and the format is validated, (2) the file content is decoded into its raw representation, (3) the data is re-encoded in mkv format with optimal settings, (4) the converted file is ready for download.
CocoConvert's converter handles the entire pipeline server-side using FFmpeg, Sharp, and qpdf — battle-tested libraries used by streaming platforms and enterprise tools. Files are encrypted in transit and deleted within 24 hours.
This conversion is ideal when you When you specifically need a MKV file for your workflow. For the opposite direction, CocoConvert also supports MKV to MP4 conversion.
How to Convert MP4 to MKV
- 1
Upload .mp4 file
Select your MP4 file by dragging it to the upload zone or using the file picker. Batch upload is available for multiple files.
- 2
Choose .mkv
Set MKV as the output format. The converter uses optimal settings based on the MP4→MKV conversion profile.
- 3
Convert
The server-side engine decodes your MP4 file and re-encodes it as MKV. Processing time depends on file size and complexity.
- 4
Download result
Grab your converted .mkv file. Multiple output files can be downloaded together.
What Happens When You Convert MP4 to MKV
Your MP4 video is transcoded — video and audio streams are decoded and re-encoded into the MKV container. This is a lossy process that takes time proportional to the video duration.
Your MP4 file is demuxed — video, audio, and subtitle streams are separated
The video stream is decoded frame-by-frame, then re-encoded with MKV-compatible codecs (typically H.264 for MP4)
The audio stream is decoded and re-encoded (or copied if the codec is compatible)
Subtitle and chapter data is preserved where the target supports it
Streams are muxed into the MKV container and the file is saved
MP4 vs MKV — Detailed Comparison
| Feature | .MP4 | .MKV |
|---|---|---|
| Full Name | MPEG-4 Part 14 | Matroska Video |
| Compression | Lossy | Lossy |
| Color Depth | 8-bit (H.264) or 10-bit (H.265/AV1) | 8–10 bits (codec dependent) |
| HDR Support | Yes | Yes |
| Typical File Size | 50–200 MB per minute (1080p H.264) | 50–200 MB per minute |
| Platform Support | Universal | Very Wide |
| Browser Support | Universal | Limited |
| Year Created | 2001 | 2002 |
| Open Standard | Yes | Yes |
Should You Convert MP4 to MKV?
When to Convert
- ✓When you specifically need a MKV file for your workflow
When NOT to Convert
- ✗You're converting just because the file "seems old" — re-encoding lossy-to-lossy always degrades quality
Common Mistakes When Converting MP4 to MKV
"I'll convert to MKV and then back to MP4 — it'll be the same"
Each lossy conversion cycle permanently degrades quality. Going MP4 → MKV → MP4 will produce a noticeably worse file than the original. Always keep your source file.
Frequently Asked Questions
What is the difference between MP4 and MKV?
MP4 (MPEG-4 Part 14) is the universal video container supporting H.264/H.265 codecs — plays on virtually every device. MKV (Matroska) is an open container supporting virtually any codec, multiple audio tracks, and subtitles. Full Name: MP4 uses MPEG-4 Part 14, while MKV uses Matroska Video. Compression: MP4 uses Lossy, while MKV uses Lossy. Color Depth: MP4 uses 8-bit (H.264) or 10-bit (H.265/AV1), while MKV uses 8–10 bits (codec dependent).
Does MP4 to MKV conversion affect quality?
MP4 uses lossy compression, and so does MKV. Converting means decoding and re-encoding — each cycle can permanently degrade quality. Convert from the original source file whenever possible.
Which format has better compression, MP4 or MKV?
MP4 uses lossy compression. MKV uses lossy compression. The better choice depends on whether you prioritize file size or quality.
How long does MP4 to MKV conversion take?
Most conversions finish in seconds. Larger files or complex video content may take 10–30 seconds. CocoConvert processes files in parallel for batch jobs.
Is MP4 or MKV better for long-term storage?
Both formats use lossy compression, so consider keeping your original source file for long-term storage.
Versions are pinned in our worker Dockerfile and re-built via CI on every change.