Convert MP4 to MKV
Max file size 100mb.
MP4 vs MKV Format Comparison
| Aspect | MP4 (Source Format) | MKV (Target Format) |
|---|---|---|
| Format Overview |
MP4
MPEG-4 Part 14
The most widely used video container format, standardized as ISO/IEC 14496-14. MP4 wraps H.264/H.265 video and AAC audio into a streamable container optimized for web delivery, mobile playback, and broadcast. Its universal device support — from smartphones to smart TVs to web browsers — makes it the default choice for video distribution, though its rigid codec constraints and limited multi-track capabilities can be restrictive for archival and professional workflows. Standard Lossy |
MKV
Matroska Video Container
An open-source, royalty-free container format designed to hold virtually any combination of video, audio, subtitle, and metadata tracks within a single file. MKV supports unlimited streams, ordered chapters, segment linking, and advanced features like variable frame rate and 3D video. Created in 2002 by the Matroska project, it has become the preferred format for high-quality video archiving, Blu-ray rips, and media libraries where maximum flexibility matters more than universal device compatibility. Modern Lossless |
| Technical Specifications |
Container: MPEG-4 Part 14 (ISO base media file format)
Video Codecs: H.264, H.265/HEVC, AV1, MPEG-4 ASP Audio Codecs: AAC, MP3, AC-3, E-AC-3 Max Resolution: Up to 8K (7680×4320) Extensions: .mp4, .m4v, .m4a |
Container: Matroska (EBML-based binary format)
Video Codecs: Any (H.264, H.265, VP9, AV1, FFV1, etc.) Audio Codecs: Any (AAC, FLAC, DTS, TrueHD, Opus, etc.) Max Resolution: Unlimited (depends on codec) Extensions: .mkv, .mka (audio), .mks (subtitles) |
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| Processing & Tools |
MP4 encoding and muxing with FFmpeg: # Encode video to MP4 with H.264 ffmpeg -i input.avi -c:v libx264 -crf 23 \ -c:a aac -b:a 192k output.mp4 # Fast-start for web streaming ffmpeg -i input.mp4 -c copy \ -movflags +faststart output.mp4 |
MKV muxing and stream management with FFmpeg and MKVToolNix: # Remux MP4 to MKV (no re-encoding) ffmpeg -i input.mp4 -c copy output.mkv # Add subtitle track to MKV mkvmerge -o output.mkv input.mkv \ --language 0:eng subs_en.srt \ --language 0:fra subs_fr.srt # Add chapters mkvpropedit output.mkv --chapters chapters.xml |
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| Version History |
Introduced: 2001 (ISO/IEC 14496-14)
Current Version: MP4 (2003), CMAF (2018) Status: Universal standard, actively maintained Evolution: QuickTime (1991) → MPEG-4 Part 14 (2003) → CMAF (2018) |
Introduced: 2002 (Matroska project)
Current Version: Matroska v4 (WebM profile), EBML v1 Status: Active open-source development Evolution: MCF (2002) → Matroska v1 (2002) → v2 (2003) → v4/WebM (2010) |
| Software Support |
Media Players: VLC, mpv, Windows Media Player, QuickTime
Web Browsers: All browsers (H.264/H.265 100% support) Video Editors: Premiere Pro, DaVinci Resolve, Final Cut Pro Mobile: iOS, Android — native playback CLI Tools: FFmpeg, HandBrake, MP4Box, Bento4 |
Media Players: VLC, mpv, PotPlayer, MPC-HC, Kodi
Web Browsers: Not natively supported (WebM subset only) Video Editors: DaVinci Resolve, Kdenlive, Shotcut Mobile: Android (MX Player, VLC), iOS (VLC, Infuse) CLI Tools: FFmpeg, MKVToolNix, HandBrake, MediaInfo |
Why Convert MP4 to MKV?
Converting MP4 to MKV unlocks the full potential of the Matroska container — a format designed from the ground up for maximum flexibility. While MP4 is constrained by the MPEG-4 specification to a narrow set of codecs and features, MKV can hold virtually any video codec (H.264, H.265, VP9, AV1, FFV1), audio codec (AAC, FLAC, DTS, TrueHD, Opus), and subtitle format (SRT, ASS/SSA, PGS, VobSub) in a single file with unlimited tracks. If your MP4 workflow hits limitations — especially around multi-track audio, styled subtitles, or chapter management — MKV removes those constraints entirely.
The most common reason for MP4-to-MKV conversion is adding multiple audio and subtitle tracks. An MP4 movie might have a single English audio track and no subtitles, but the same content in MKV can carry the original Japanese audio, an English dub, a director's commentary, and subtitles in 15 languages — all selectable by the viewer. This makes MKV essential for multi-language content, anime with styled ASS/SSA subtitles, and educational videos with chapter-based navigation.
For video archiving and media libraries, MKV is the superior choice. Media servers like Plex, Jellyfin, and Kodi handle MKV natively, providing automatic track selection based on user language preferences. MKV also supports file attachments (embedded fonts for subtitles, cover art thumbnails) and ordered chapters that let you skip intros or link episodes. The format's open-source nature ensures long-term accessibility — there are no patents or licensing fees that could restrict future use.
The conversion from MP4 to MKV is typically a lossless remux operation — the video and audio streams are copied directly into the MKV container without re-encoding. This means zero quality loss, instant conversion speed, and identical file sizes. The only trade-off is reduced device compatibility: MKV won't play natively in web browsers or on iOS without third-party apps. Use MKV for storage and home theater, and keep MP4 for web delivery and mobile sharing.
Key Benefits of Converting MP4 to MKV:
- Unlimited Tracks: Add any number of audio, subtitle, and video streams
- Lossless Remux: Convert without re-encoding — zero quality loss, instant speed
- Styled Subtitles: Support for ASS/SSA with fonts, colors, and positioning
- Chapter Navigation: Ordered chapters with nested editions for complex navigation
- Any Codec: Container accepts virtually any video and audio codec
- Media Server Ready: Native support in Plex, Jellyfin, Kodi, and Emby
- Open Source: Royalty-free, patent-free format with active development
Practical Examples
Example 1: Building a Multi-Language Movie Library
Scenario: A film collector has MP4 movies with only English audio and wants to add original-language audio tracks and multilingual subtitles for a Plex media server.
Source: inception_2010.mp4 (4.2 GB, 1920x1080, H.264, AAC 5.1 English) Conversion: MP4 → MKV (remux + add tracks) Result: inception_2010.mkv (4.5 GB, same video, 3 audio + 8 subtitle tracks) Workflow: 1. Remux MP4 to MKV container (lossless, instant) 2. Add Japanese DTS-HD audio track from Blu-ray source 3. Add French AC-3 audio track 4. Add subtitle tracks (EN, FR, DE, ES, JP, KO, ZH, PT) 5. Add chapter markers for scene navigation ✓ Plex auto-selects audio/subs based on user language ✓ All tracks selectable via player UI during playback ✓ Chapter thumbnails visible in Plex timeline ✓ Original video quality preserved (no re-encoding)
Example 2: Anime Collection with Styled Subtitles
Scenario: An anime fan has episodes in MP4 format with hardcoded English subtitles and wants to switch to soft subtitles with proper typesetting using ASS/SSA format.
Source: attack_on_titan_s01e01.mp4 (350 MB, 1920x1080, H.264, AAC stereo) Conversion: MP4 → MKV (remux + ASS subtitles + fonts) Result: attack_on_titan_s01e01.mkv (355 MB, same video + subs + fonts) Anime workflow: 1. Remux MP4 video/audio to MKV (lossless) 2. Attach ASS subtitle file with styled typesetting 3. Embed required fonts as MKV attachments 4. Add Japanese original audio track ✓ Subtitles with proper fonts, colors, and positioning ✓ Signs and songs translated with on-screen styling ✓ Toggle between English/Japanese audio ✓ Subtitle fonts display correctly on any device
Example 3: Educational Course with Chapter Navigation
Scenario: An online course creator has a 3-hour lecture as a single MP4 file and wants to add chapter markers so students can jump between topics, plus add a secondary audio track with Spanish narration.
Source: python_masterclass_full.mp4 (2.8 GB, 1920x1080, 3 hours) Conversion: MP4 → MKV (remux + chapters + Spanish audio) Result: python_masterclass_full.mkv (3.1 GB, chapters + 2 audio tracks) Course structure: Chapter 1: Introduction (00:00:00) Chapter 2: Variables and Data Types (00:15:30) Chapter 3: Control Flow (00:45:00) ...12 chapters total... ✓ Students click chapter markers to jump to topics ✓ Spanish audio track selectable for bilingual students ✓ Chapter thumbnails show topic previews in VLC/Kodi ✓ Single file contains complete course with navigation
Frequently Asked Questions (FAQ)
Q: Does converting MP4 to MKV lose any quality?
A: No. The standard MP4-to-MKV conversion is a remux operation — the video and audio streams are copied bit-for-bit into the new container without re-encoding. The output MKV file contains the exact same video and audio data as the source MP4. File size remains virtually identical (MKV overhead is negligible). This is one of the few format conversions that is truly lossless.
Q: Will MKV files play on my smart TV?
A: Most modern smart TVs (Samsung, LG, Sony, TCL) support MKV playback natively, especially with H.264/H.265 video and AAC/AC-3 audio. However, some older TVs and certain brands may not recognize MKV containers. If your TV doesn't play MKV directly, media servers like Plex or Jellyfin can transcode on-the-fly to a compatible format. Android TV and Google TV have excellent native MKV support.
Q: Can I play MKV files on iPhone or iPad?
A: iOS does not natively support MKV playback in the Files app or Safari. However, third-party apps like VLC, Infuse, and nPlayer handle MKV files perfectly, including multiple audio tracks and subtitles. If you use Plex or Jellyfin with an iOS client, the server transcodes or direct-plays the MKV content seamlessly. For maximum iOS compatibility without apps, keep an MP4 copy for mobile use.
Q: What is the difference between MKV and WebM?
A: WebM is a restricted subset of the Matroska container, limited to VP8/VP9/AV1 video and Vorbis/Opus audio. MKV is the full Matroska specification supporting any codec. WebM was created by Google specifically for web browser compatibility. Think of WebM as "MKV for the web" — same container technology, but with a restricted codec profile that browsers can guarantee to decode.
Q: Can I add subtitles to an MKV file after conversion?
A: Yes, and this is one of MKV's greatest strengths. Use MKVToolNix (free, cross-platform) to add or remove subtitle tracks, audio tracks, chapters, and attachments without re-encoding the video. The command mkvmerge -o output.mkv input.mkv subs.srt adds a subtitle file in seconds. You can also use the MKVToolNix GUI for a visual drag-and-drop workflow.
Q: How much larger is an MKV file compared to the same MP4?
A: When remuxing (copying streams without re-encoding), the MKV file is typically within 0.1-0.5% of the MP4 file size — the container overhead is negligible. A 4 GB MP4 becomes a 4.01-4.02 GB MKV. The file gets noticeably larger only when you add additional audio tracks, subtitle files, or embedded fonts. A movie with 3 audio tracks and 10 subtitle tracks might add 200-500 MB compared to a single-track MP4.
Q: Can MKV hold lossless video and audio?
A: Yes. MKV supports lossless video codecs (FFV1, HuffYUV, Lagarith) and lossless audio codecs (FLAC, TrueHD, DTS-HD Master Audio). This makes MKV the preferred container for professional video archiving, Blu-ray backup with original lossless audio, and preservation workflows where bit-perfect quality is mandatory. MP4 does not support most of these lossless codecs.
Q: Should I convert all my MP4 files to MKV?
A: Not necessarily. If your MP4 files play fine on all your devices and you don't need multiple audio tracks, advanced subtitles, or chapter navigation, there's no benefit to converting. Convert to MKV when you need specific MKV features: multi-language audio, styled subtitles, chapter markers, embedded fonts, or lossless codec support. Keep MP4 for web streaming, social media, and mobile sharing where compatibility is paramount.