MKV vs MP4: 7 Key Differences Between MKV and MP4 Formats

MKV and MP4 stand out as popular video container formats, widely used by folks around. Yet, there are moments when users find themselves converting MKV to MP4 or vice versa. It's not uncommon for some users to scratch their heads, pondering over which format suits their needs best. Take this scenario, for instance: "I've got a stack of DVDs, and I want to use WinX DVD Ripper Platinum to make copies for backup and convenient viewing. Now, should I go for MKV or MP4? Which one gives me better quality?" Let's dive into a comparison of MKV and MP4, looking at aspects like quality, file size, supported video and audio codecs, and more, so we can make sense of these two formats.

Part 1. MKV vs MP4: Detailed Comparison

Both MKV and MP4 are popular video container formats to store multimedia data including videos, audios, still images and subtitles. They are also used to stream content over the internet as well. But, they are quite different and have pros/cons in terms of individual needs.

#1. License

MKV is supported by a non-profit organization called association loi 1901 and the specifications are open to everyone. MKV is a royalty-free open standard under GNU L-GPL license for personal use and also has free parsing and playback libraries under BSD license available for commercial companies. MP4 (ISO/IEC 14496-14 standard) is patent protected format making use of DRM to restrict copying.

#2. Supported Audio/Video Codec Formats

MKV can store unlimited multimedia content, including video, audio, images, and subtitle tracks. MKV format is commonly used for movies and TV shows. It supports virutally all video/audio coding formats. MKV may allow for codecs that mp4 does not.

MP4 has specific formats supported, including audios of MPEG-2/4 (HE)-AAC, MPEG-1/2 Layers I, II, III (MP3), AC-3, Apple Lossless, ALS, SLS, Vorbis and videos of MPEG-2 Part 2, MPEG-4 ASP, H.264/MPEG-4 AVC, H.263, VC-1, Dirac. MP4 format also support some less used compression, such as Apple Lossless, Free Lossless Audio Codec (added in late 2018), and Opus (added in late 2018).

Both MKV and MP4 can be encoded with HEVC/H.265 video codec formats supporting UHD resolutions, 4K 2160p and 8K 4320p.

One difference between MKV and MP4 in audio support is that MKV supports FLAC while MP4 doesn't. FLAC stands for Free Lossless Audio Codec. It is an audio coding format for lossless compression of digital audio and better than any other audio formats. Although MP4 can also support lossless audio ALAC but this format is significantly less efficient than FLAC.

#3. Subtitle Support

MKV has better support for subtitles. MKV supports SSA/ASS subtitles while MP4 does not.

#4. Quality

MKV vs MP4, which provides better quality? MKV is better quality? No. MP4 is better quality? No. Actually, the quality of a file is defined by the codecs used in the container and not the container itself. Both MKV and MP4 are containers and not encoding formats. When MKV and MP4 encapsulate the same same audio and video codecs such as H.264+AAC and use the same settings, they will be equal in quality.

#5. Size

Are MKV files bigger than MP4? Actually not. MKV and MP4 are just container formats. What determines the file size is the codec and the bitrate of the video. When the video encoded with the same codec and same bitrate, it is the same size.

MKV usually has a larger file size than MP4 videos due to the support for the extra features, multiple audio tracks, and subtitle tracks.

If you find MKV videos have smaller size but higher resolution than MP4, this is probably because the MKV files use a more advanced codec with a higher compression ratio.

#6. Usage and Compatibility

Best scenarios for using MKV

• Archiving High-Quality Videos: MKV's forte lies in preserving the highest quality of audio and video. It is an excellent choice when you want to archive your videos without any compromise on the original visual and auditory experience. This is particularly beneficial for filmmakers, videographers, or anyone who places a premium on maintaining pristine video quality.
• Storing Multimedia Content with Multiple Tracks: MKV's ability to support multiple audio and subtitle tracks makes it an ideal format for multimedia enthusiasts. If your video project involves diverse language options, commentary tracks, or various subtitle choices, MKV provides the flexibility to store all these elements in a single file without sacrificing quality.

Optimal situations for MP4:

• Online Streaming and Sharing: MP4's widespread support across streaming platforms, social media, and video-sharing websites makes it the format of choice for content meant for a broad audience. It ensures that your videos can be easily uploaded, shared, and streamed without compatibility concerns, catering to the demands of the online content ecosystem.
• Compatibility with Various Devices and Platforms: When creating content for diverse audiences using different devices, MP4 shines due to its universal compatibility. Whether your audience is accessing content on smartphones, tablets, computers, or smart TVs, MP4 ensures a seamless playback experience without the need for additional codecs or software.
• Balancing Quality and File Size for Efficiency: MP4's efficient compression algorithm strikes a balance between maintaining decent video quality and reducing file sizes. This is particularly advantageous in scenarios where storage space is a consideration, such as when distributing videos via email or storing them on devices with limited capacity.

#7. File Extensions

.mp4 filename extension is commonly used for MP4 video files. Many other filename extensions are also used to indicate intended content.

• .m4a - Audio-only MPEG-4 unprotected files.
• .m4p - MPEG-4 files with audio streams encrypted by FairPlay Digital Rights Management commonly used by iTunes and Apple Music.
• .m4b - audio book and podcast file coming with chapter markers, images, and hyperlinks, etc.
• .m4v - Raw MPEG-4 Visual bitstreams. Handbrake outputting video files (encoded with H.264 MP4) often has .m4v filename extension.
• .3gp and .3g2 - MPEG-4 Part 12, 3GP used by mobile phones in the past.

MKV format uses filename extensions, .mkv, .mk3d, .mka, .mks, .mkv for video (subtitles and audio), .mk3d(stereoscopic video), .mka (audio-only files), and .mks (subtitles only). .mk3d, .mka, and .mks are less used. Common MKV video files come with .mkv extension.

Part 2. MKV vs MP4 - Which Format to Choose

To sum up, MP4 format has better compatibility and is widely supported by mobile devices. MKV is commonly used for high quality videos and comes with larger file size. From the conclusion of MKV vs MP4 comparison, it's hard to tell which format is better. It is incorrect to say MKV file is bigger than MP4 and better quality than MP4. They are just containers and have no effect upon file size and quality. You should compare the encoding format and bitrate in these container formats. Which format to choose, MKV or MP4? You should make your decision depending on your specific needs and preferences.

If you want to rip DVD with excellent quality and selectable tracks and your device supports MKV format, MKV is a good choice. On the other hand, MP4 is much more appropriate for playing videos on your Android devices and game consoles. Certainly, you can opt for converting DVD to MP4 encoded with H.264 codec for playback on nearly any devices with possible highest quality.

Part 3. FAQs about MKV and MP4

1. How do I convert MKV to MP4?

It's easy to convert MKV to MP4, especially with the best video converters like Winxvideo AI. After downloading and installing this software on your computer, you can convert video format from MKV to MP4 within 3 simple steps.

• Step 1. Open Winxvideo AI, select Video Converter, and click the + Video button to load the MKV files you want to convert to MP4.
• Step 2. Choose a desired MP4 preset. There are MP4 presets for PC, Mac, Apple, Android, TV, YouTube, and more.
• Step 3. Hit RUN to begin converting MKV to MP4. If you want to convert MKV to MP4 without re-encoding, you should check Auto Copy before hitting the RUN button.

2. For streaming over Plex, which video format is better, MKV or MP4?

MKV is more versatile and can be played on Plex if it is encoded with supported video audio codecs. However, MP4 is easier to direct play in Plex (better stream, less buffering).

3. Assuming file sizes are the same, what format has better quality video, MKV or MP4?

Both MKV and MP4 are container formats and can't determine the quality of a video. It is the encoding of the video inside the container that matters. If a H.265-encoded MKV file is the same size as a H.264-encoded MP4 file, the MKV file should have better quality because the encoding format H.265 is superior to H.264 offering from 25% to 50% better data compression at the same level of video quality.

4. MKV VP9 vs MP4 H.264, which to choose?

In this case, we should compare VP9 and H.264. VP9 is a fairly new video format invented by Google as a royalty-free alternative to the heavy patented HEVC/H.265 format, aiming to reduce the file size of 4K video which would simply require much more server capacity with older video formats like H.264. So when downloading online video you should choose VP9 if you want the highest quality like 1080p or 4K. However, VP9 isn't a good choice for lower resolutions because it takes a lot longer to encode video to VP9 with the same quality as a well-encoded H.264 video.

5. Should I save my movies in MP4 or MKV?

It depends on your purposes. In general, MP4 format is preferred because it is more popular. It is accepted by almost all media players, video editing software, video-sharing sites, and more.

6. Should I convert DVD to MKV or MP4?

It depends on where you want to use the digital copy and which codec you want to choose. If the video and audio codec you want to use can't be wrapped in MP4, then you can use MKV. For example, if we choose MKV container format on HandBrake, the available video codecs include H.264, H.265, MPEG-2, MPEG-4, Theora, VP8, and VP9. But if we choose MP4, we can only choose between H.264, H.265, MPEG-2 and MPEG-4.

MP4 has broader support than MKV. If the media player you want to play the digital copy on doesn't support MKV, you should choose MP4.

7. To create videos for uploading to YouTube, should I choose MP4 or MKV?

If you want to create video for YouTube, YouTube suggests you use MP4. For more details about recommended upload encoding settings, click here.

But if you record video with OBS, koala - an active member on OBS forum warned that you should never record directly to MP4. It is advisable to always record to *.mkv and let OBS remux to *.mp4 after recording by setting Settings -> Advanced -> Recording -> Automatically remux to mp4. koala said:

Any video recorded directly to mp4 is usable only, if OBS is able to finalize the video. If it isn't able to finalize the video, the video is in its entirety unreadable. OBS isn't able to finalize, if it crashes mid-recording, or if the computer crashes or has a bluescreen, or if OBS hangs, or if the disk becomes full. If all this doesn't apply to your environment, you will have no issues with directly recording to mp4. But if something bad happens, the mp4 will be broken beyond repair, so don't complain if that happens.

We had many heartbroken posts in the forum with something like: "I just did the raid of my life in my game, but the computer crashed afterwards. Now my recording is broken. What can I do?" or even "I just recorded the marriage of my child, but my computer crashed. Now my recording is broken. What can I do?" The only answer to all this is "it's gone", if the recording format turned out as mp4.