Lossless Ways To Convert ffmpeg mkv To mp4 and mp3 With Subtitles Without Reencoding

Lossless Ways To Convert ffmpeg mkv To mp4 and mp3 With Subtitles Without Reencoding

Lossless Ways To Convert ffmpeg mkv To mp4 and mp3 With Subtitles Without Reencoding

If you have ever asked questions like “how to convert MKV to MP$ with FFmpeg without losing any quality?”, then you have come to the right place. This article will guide you through the process of converting MKV to MP4 without recording with FFmpeg. It will also show you the output file during and after the process.

You may also have come across questions like how to use FFmpeg to convert MKV to MP4 and MP3. Moreover, this article compares different kinds of FFmpeg and difficulty levels at the very beginning. So do not worry anymore and read this article to figure out what FFmpeg actually is and how to convert mkv to mp4 with ffmpeg easily. 

A challenge people often confront is converting videos from mkv to mp4 container/file formats for free and easily. It is straightforward to convert mkv to mp4 using open-source software so that you don’t have to pay anything!

So, let’s start with a basic introduction to the MKV file format.

What is the MKV File Format?

Matroska Multimedia Container is a file type that can hold limitless video, audio, picture, or subtitle tracks in one file [from Wikipedia]. The file format is open-sourced, similar to MP4 and other media containers.

The different file extensions connected with Matroska are –

  • mkv for video
  • aka for audio
  • mks for subtitles
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Though the mkv file format is open to all, you can meet computers that do not play or support the mkv extension or container format. In this case, convert mkv to mp4 for system compatibility.

Let’s convert the following several sections.

Converting MKV to MP4 using VLC Player

VideoLAN produced the free, open-source, cross-platform VLC media player and streaming media server. It works on Windows, Mac, and Linux. It can play audio and video, give detailed video, codec, and metadata information, take screenshots and convert videos.

In this section, we’ll convert mkv to mp4 using VLC Player.

  1. After installing VLC, choose the “Media” tab.
  2. Select your mkv file by clicking “+Add.” After adding the file using Add, click the “Convert/Save” button, which should be activated.
  3. Select “Video – H.264 + MP3 (MP4)” as the output profile. Then choose the destination file and click “Start.”
  4. You’ll receive the converted mp4 file in a few seconds or minutes (depending on the size of your mkv video).

VLC player takes a long time to convert mkv to mp4 since it re-encodes the video. Long files may take longer to convert.

This command-line-free method converts mkv to mp4. Some choose the command line because they wish to conduct the conversion on a headless server or in a shell script.

In these instances, FFmpeg is the best option.

Converting MKV to MP4 using FFmpeg

MKV to MP4 and other video formats can be converted using FFmpeg, a free cross-platform converter. FFmpeg can also be used to stream and record media files for free. You won’t receive the standard MKV to MP4 interface with “Add File,” “Output Format,” and other optimization features. To be more specific, FFmpeg converts.mkv to.mp4 faster than popular video converters such as Audacity, Handbrake, and others.


Almost anything that people and machines have made can be decoded, encoded, transcoded, muxed, demuxed, streamed, filtered, and played. FFmpeg is also cross-platform, supporting Linux, Mac OS X, Microsoft Windows, and other operating systems.

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Many FFmpeg programmes, such as ffmpeg, ffserver, ffplay, and ffprobe, let you manage multimedia files in one place. When you first visit ffmpeg.org, you may be surprised by the black-based interface with only one blank to fill in. Simply read the following instructions to convert MKV to MP4 losslessly with FFmpeg.

FFmpeg is the world’s best open-source video processing and compression library. It’s versatile, stable, and employed in commercial video applications. Installing FFmpeg is easy. Install FFmpeg on Windows, Linux, and macOS, then return.

Here’s how to convert mkv to mp4 losslessly with FFmpeg


VideoName.mkv copy output -c:v VideoName.mp4

Finally. One FFmpeg line converts mkv to mp4. Parameters mean the following:

-i inputVideoName.mkv: Your mkv input file.

Copy -c: a copy directs FFmpeg to copy video and audio from mkv to mp4.

The Target mp4 file is outputVideoname.mp4.

Because you’re directing FFmpeg to immediately copy audio and video from one container format to another, there’s no re-encoding, and the copy is fast.

If uncomfortable with the command line, consider Handbrake to convert mkv to mp4. Let’s see.

Converting MKV to MP4 using Handbrake

Handbrake is a superb video format converter if you prefer a GUI over the terminal and command lines. Handbrake is a free, open-source Windows, Mac, and Linux program. If you’re new to Handbrake, read our tutorial.

Open the mkv file using File->Open Source. Handbrake shows mkv file details. Choose MPEG-4 (format) on the Summary tab to convert mkv to mp4.

Choose a file name in the “Save As” dialogue box and click “Start” to convert containers. Handbrake converts mkv to mp4 slowly since it re-encodes the video. Long files may take longer to convert. Handbrake optimizes mp4 files for email, WhatsApp, and other messaging applications.

Finally, after conversion, the mp4 file should be in the output folder.

MKV to MP4 quality loss?

You can convert an mkv file to mp4 lossy or lossless. Let’s investigate –

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You transfer mkv video to mp4 without altering anything. FFmpeg and a copy operation can do this (also called transmuting).


If you modify the video quality or resolution, the software you use to convert it will re-encode it. Handbrake, VLC, and FFmpeg can do lossy conversion.

FFmpeg MKV-to-MP4 FAQs

FFmpeg MKV to MP4 conversion lacks audio.

This problem has two causes. MKV files have DTS audio. Your MP4 player may not support it. Your player’s supported audio codecs are AC3, MP2, WAV1, WAV2, AAC, Vorbis, MP3, and Opus.

Old FFmpeg. Download FFmpeg to install the updated audio codec.

How to quickly convert MKV to MP4?

AnyMP4 Video Converter Ultimate supports MKV hardware acceleration. To convert MKV to MP4 faster, enable acceleration.


This post explains how to convert MKV to MP4 using VLC, Handbrake, or FFmpeg. All three ways work well; it depends on whether you prefer GUI or command-line tools.

Try them out.

Thanks, and have fun streaming!