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How to Convert MKV to MP4 Quickly Without Quality Loss

MKV is just a container, storing video, audio, subtitle tracks in a variey of codecs, such as HEVC, H.264, DTS and Dolby Digital audio etc. This means you may encounter MKV not playing error owing to the codec issue. And MKV always saves large-sized video in HD or 4K UHD resolution, which requires high of hardware, leading in MKV playback error on general computers. For example, you may find 4K HEVC MKV files not playing on Windows, MKV plays pixelated/blocky, no sound, black screen or large 4K MKV stutters on computers, mobiles, TVs, Xbox, PS4 etc. To fix it, you absolutely need to convert video files from MKV to MP4 with a free MKV video converter!

WinX HD Video Converter Deluxe Is the Best Way to Go!

WinX HD Video Converter Deluxe - Equipped with Full Hardware Acceleration, High Quality Engine and more cutting-edge technologies, it can transcode MKV to MP4 for playback on more devices at the fastest speed while keeping nearly lossless quality. Hundreds of premade presets allow you to convert MKV to iPhone, iPad, Android, Windows Mobile, Xbox or other devices directly.

Part 1: Why Should You Convert MKV to MP4?

1. MKV format or codec is not compatible with your device/player.
There is a great possibility that your MKV player fails to support your MKV files as MKV can be encoded with various codecs like VP9, HEVC, MPEG4, H.264, VP8, Xvid, AAC, MP3, DTS audio codec etc. You may find your MKV files no sound, black screen or absolutely not playing.

2. The computer hardware is not good enough to play MKV in 4K resolution.
4K (HEVC) MKV videos ripped from 4K UHD Blu-ray discs or downloaded from online sites cannot be opened in the under-powered computer, causing errors like pixelated 4K MKV playback, or dropping frames. Learn More: Minimum specs configuration for 4K HEVC MKV playback >>

3. MKV file is always in large size, making it hard for playback and storage.
MKV is publicly known as an ideal format for HD/4K videos, which would occupy several or even dozens of gigabytes. But most media players have no access for such a large size video, and it's hard to save it. For that, converting MKV to MP4 can partly reduce 4K MKV file size.

4. MP4 format owns better compatibility, intact quality and ability to retain/abandon original MKV tracks.
On the contrary, MP4 is widely supported by a range of devices and it reserves high audio & video quality. You don't have to worry that the original MKV elements are missing as MP4 is able to retain the multiple audio tracks, multilingual subtitles, chapter points etc. after MKV to MP4 conversion. Of course, you can selectively remove some unwanted tracks to get a smaller size video in MP4.

Part 2: WinX HD Video Converter Deluxe - The Best MKV to MP4 Converter

You may more or less have used some MKV converter to change MKV format to MP4. But there still are a great deal of users trying to find out an easy yet effective video converter since they get into all sorts of MKV to MP4 converting errors, such as huge quality loss, larger output file size than input, audio/video out of sync, extremely slow converting speed, empty MP4 output and even a failed conversion.

Is there a MKV converter which is free from such conversion errors? WinX HD Video Converter Deluxe is definitely the first choice, as it ensures a fast and smooth MKV to MP4 conversion with original quality, distinctly smaller output file.

What Makes WinX HD Video Converter Deluxe Superior to Others?

Average User Rating: ★★★★☆

  1. Convert any videos to 420+ preset profiles, including MP4, MOV, FLV, HEVC, H.264, iPhone iPad, Android, HDTV, Xbox, PS4 and more.
  2. Almost original quality reserved, thanks to the Auto Copy and High-quality engine. It's able to change MKV to MP4 without re-encoding, as well as adopts the same VBR encoding with MKV, in which you can choose the desired quality level and/or a range of allowable bitrates.
  3. Compress MKV videos smaller up to 90% file size reduction, by downscaling resolution, changing codec, tweaking bit rate, frame rate, aspect ratio, cropping frame size, or trimming the video length and so on.
  4. Boast the world's No.1 fast conversion speed. It makes full use of CPU and GPU, accelerating video conversion 47X real-time faster on machines configured with both QSV-allowed Intel processor (2-6th generation) and CUDA/NVENC-enabled NVIDIA GPU.

WinX HD Video Converter Deluxe Advantages Over Online MKV Converters

For the lure of no download and installation, many users may choose free online video converters for MKV-to-MP4 conversion. It does help to transcode single and relatively small MKV files to MP4. While comparing with WinX HD Video Converter Deluxe, it's far backward from for converting 4K UHD, high frame rate HD MKV files.

Differences between online and desktop MKV converters
Differences between online and desktop MKV converters

WinX HD Video Converter Deluxe is a simple-to-use program which comes with advanced features for encoding video files. - Editor's Review from Softpedia)

Part 3: How to Convert MKV to MP4 on PC/Mac - 3 Simple Steps

After downloading and installing WinX HD Video Converter Deluxe onto your computer, you only need 3 simple steps to get MKV converted to MP4.

Free Download WinX HD Video Converter for Windows 10/8/7
Free Download WinX HD Video Converter for macOS Catalina and lower

Step 1: Load target MKV files.

Open this converter and load an MKV file you want to decode from your computer, external hard drive, USB drive: Click + Video button at the top left corner of main interface, and then browse and open target items. If you need to transcode multiple MKV files, simply choose all of them for batch conversion. It will save you much time and energy.

Load target MKV files
Load target MKV files

Step 2: Select MP4 in output profile.

After loading source files, Output Profile panel will pop up automatically. In this screen, you will find many preset MP4 output profiles. You can choose one based on your own needs. Here let's select MP4 Video (codec: H.264+ AAC) under General Profiles category for good quality preservation and compression ratio.

Select MP4 in output profile
Select MP4 in output profile

Step 3: Get it Started Now.

Before any further, you can change the destination folder. By default, output files will be stored in C:\Users\admin\Videos\WinXVideos\. Choose another one by clicking Browse button if you like. Once in place, just click RUN button - a blue round one - to start converting MKV video files to MP4 instantly. After then, you're able to play output MP4 video on desktop, HDTVs, PS4, Xbox, Plex, mobiles and more.

Start converting MKV to MP4 now
Start converting MKV to MP4 now

Optionally, if you want do more with WinX HD Video Converter Deluxe, try the following advanced settings:

  1. Resize MKV video file size: Click gear-shaped setting icon to open up a window where you can compress 4K MKV to 1080p/720p, tweak the bitrate and frame rate to be matchable with the resolution, change aspect ratio to 16:9 for black bars removal.
  2. Trim/crop MKV video: Click Edit, then go to Trim tab and Enable Trim to set the start/end time to cut MKV video length. Or go to Crop & Expand tab and Enable Crop to crop the MKV frame size on the screen. BTW, you can also add external subtitle to MKV below Subtitle tab.
  3. Select the target track or disable unwanted tracks: Back to the main interface, MKV video/audio/subtitle tracks are listed ahead an up-and-down arrow. Click the corresponding arrow, you can select your target video/audio/subtitle track or disable multitracks at all.
  4. Enhance output quality: Go Output profile window, move the slider to HQ/Slow, which will make slow down the converting speed slightly yet with higher quality. Meanwhile, you're always suggested to tick on the box of Use High Quality Engine.
  5. Speed up MKV to MP4 conversion: Make sure you have tick on the Intel/nIVDIA Hardware Accelerator box if your computer is configured with a qualified graphic card. It will accelerate MKV to MP4 conversion speed up to 47X real-time faster.

Video Tutorial: How to Convert MKV to MP4 without Losing Quality

Part 4: FAQs on MKV to MP4 Conversion

Q1: Audio gets out of sync after converting from MKV to MP4.

You can press "j" or "k" on your keyboard to reduce or add delay in VLC player to fix it. But the changes cannot be saved, as you close VLC and open the file in another media player, the audio goes back out of sync. To permanently make audio matched with video, you can try another video converter to re-encode MKV to MP4.

Q2: Isn't there a program to change MKV to MP4 format with no remuxing, no quality loss?!?!

WinX HD Video Converter Deluxe is what you're looking for, which can transcode MKV to MP4 without quality loss within 3 steps. All you need is to load MKV file > choose MP4 as format > Press RUN button to make everything done. Free download it to have a try!

Q3: HandBrake doesn't compress my file after MKV to MP4 conversion, but makes it bigger!

Maybe your source MKV file has a lot of grain to it. Grain will balloon file size tremendously. You can go to RF 22 on the quality slider or use the Denoise Filter in picture settings to remove some of the grain. Either or both will reduce the final file size.

Q4: MKV to MP4 process completed successfully in DVDFab, but no output file!

It looks like DVDFab is not able to detect a GPU, while it should detect Intel QuickSync. You can try with a complete reinstall of DVDFab. If it not working, maybe it's time to consider another Windows 10 video converter.

Q5: Subtitles get messed after converting MKV to MP4 with HandBrake...

You can delete the unwanted subtitle tracks and reserve the one you desired only. Or burning your desired foriegn subtitle to the video is also a good option.

Q6: HandBrake gets really slow (1-2 frames per second) even with a new fast core i3-8100 CPU with 16 GB of RAM.

Handbrake is always going to transcode the contents of the file you give it, leading in slow Handbrake encoding without hardware acceleration. Check whether the Handbrake hardware acceleration is enabled. Actually, if what you want to do is just "repackage" the existing video and audio into a different container Handbrake isn't a great tool for that as it will re-encode everything rather than just passing all ready encoded streams through. Why not try a Handbrake alternative to change MKV format to MP4 without re-encoding.

Part 5: MKV vs. MP4: What's the Difference

Both MKV and MP4 are container to save multimedia data like video, audio, subtitle tracks. But they're quite different and have pros and cons in terms of individual needs.




Video Supported

H.264, H.265, MPEG1, MPEG2, MPEG4 …

H.264, H.265, Xvid, MPEG4, …

Audio Supported




8bit, 10bit

8bit, 10bit

Closed Caption Supported


Not available


Same high

Same high

File Size

Relatively large

Relatively small

Platform Compatibility

Not so good on mobile devices

Very good on both PCs and mobile devices

Related external sources:

[1] MKV: MKV is an open standard container format, which can hold an unlimited number of video, audio, picture, or subtitle tracks in one file...
[2] MP4: MPEG-4 Part 14 or MP4 is a digital container format commonly used to store video and audio, as well as other data such as subtitles and still images...


Jack Watt

Jack Watt is a sought-after editor at Digiarty. He is responsible for digital and multimedia world, delivering definitive video and audio related software reviews, enlightening guides, and incisive analysis. As a fan of Apple, Jack Watt also brings his experience to more readers and focuses on writing of the Apple ecosystem at large.

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