Can VLC convert MKV to MP4 without losing quality?

Not in practice. VLC's Convert/Save function re-encodes the video by default, which introduces one generation of compression loss. You can try setting the video codec to 'Keep original video track,' but this mode is unreliable — it often produces files with sync issues or missing audio. A tool designed for remuxing copies the streams bit-for-bit with zero quality loss.

Why does my VLC-converted MP4 have no audio?

This is VLC's most common conversion bug. It usually happens when the MKV contains audio in a format VLC's muxer doesn't handle well during conversion — Opus, DTS, and FLAC tracks are frequent culprits. The file plays fine in VLC's player, but the converter drops or corrupts the audio stream. Switching the audio codec to MPEG Audio or re-encoding to MP3 sometimes helps, but a remux tool that copies all compatible streams avoids the problem entirely.

Why is VLC conversion so slow?

VLC decodes every video frame and compresses it again from scratch, just like any other re-encode. A 90-minute 1080p file can take 20–60+ minutes depending on your CPU. If your MKV already contains H.264 or H.265 video, this work is unnecessary — a remux copies the streams without decoding and finishes in seconds.

Is VLC a good video converter?

VLC is an excellent media player. Its conversion feature is a secondary function that works for simple cases but lacks the reliability, error handling, and codec support of dedicated converters. For MKV to MP4 specifically, the most common outcome people want — same video in a different container — is better served by a remux tool that doesn't re-encode at all.

What should I do if VLC crashes during MKV conversion?

VLC's converter can hang or crash on files with multiple subtitle tracks, unusual codecs, or very large files. Try disabling subtitle passthrough, or use a different profile. If the goal is just to get an MP4 that plays everywhere, a browser-based remux avoids VLC's muxer issues entirely — it processes the file locally and handles edge cases like HEVC, multiple audio tracks, and text subtitles automatically.

August 17, 2026

How to Convert MKV to MP4 with VLC — and Why It Often Goes Wrong

VLC can convert MKV files to MP4, and since most people already have it installed, it feels like the obvious choice. The problem is that VLC is a media player first and a converter second. Its conversion feature re-encodes everything, frequently drops audio tracks, and offers no way to do a fast lossless remux. This guide shows the exact steps to convert with VLC, explains why the results are often disappointing, and covers when a purpose-built tool does the job better.

Converting MKV to MP4 in VLC, step by step

1. Open the Convert/Save dialog

Launch VLC and go to Media → Convert/Save (or press Ctrl+R on Windows/Linux, ⌘+Shift+S on Mac). Click Add and select your MKV file, then click Convert/Save at the bottom.

2. Choose a profile

In the Convert dialog, set the Profile to Video – H.264 + MP3 (MP4). This is VLC's default MP4 profile — it re-encodes the video to H.264 and the audio to MP3 (or MPEG Audio, depending on VLC version). You can click the wrench icon to tweak codecs and bitrate, but VLC does not expose quality controls like CRF — you only get a raw bitrate target, which makes it hard to balance size and quality.

3. Pick a destination file

Click Browse next to the Destination field and choose where to save the output .mp4 file. VLC does not add the extension automatically on all platforms — type .mp4 at the end of the filename if needed.

4. Start and wait

Click Start. VLC's progress bar shows the conversion advancing, but there is no ETA or speed indicator. A feature-length 1080p file typically takes 20–60 minutes. VLC uses your CPU for the entire duration — expect fan noise and a sluggish machine until it finishes.

Why VLC's MKV to MP4 conversion often disappoints

VLC handles playback brilliantly — it decodes virtually any codec, container, and stream combination. But its converter reuses the playback pipeline in a way that creates predictable issues:

Missing audio. The single most common complaint. VLC's MP4 muxer struggles with certain audio codecs — Opus, DTS, and FLAC tracks are frequent victims. The resulting MP4 plays video fine but is silent, with no error message during conversion.
Audio/video sync drift. On longer files VLC's converter can introduce a gradual desync between audio and video, especially when the source has variable frame rate or multiple audio tracks.
No true stream copy. VLC has a “Keep original video track” option buried in the profile editor, but it is unreliable. Users regularly report corrupted output, hanging conversions, or files that won't play. In practice, you have to re-encode to get usable results from VLC.
Subtitle loss. VLC silently drops subtitle tracks during conversion. There is no option to convert text subtitles to MP4's mov_text format — they simply disappear.
No progress detail. The progress bar moves, but VLC shows no estimated time, encoding speed, or file size. You cannot tell if the conversion is running well or about to produce a broken file until it finishes.

These are not edge cases — they show up in forum threads going back years. VLC's conversion feature was never its focus, and it shows.

The faster alternative: remux instead of re-encode

Most MKV files already contain H.264 or H.265 video with AAC or AC3 audio — codecs that the MP4 container supports natively. Converting these files does not require decoding or re-encoding a single frame. The streams can be copied bit-for-bit into an MP4 container, preserving 100% of the original quality. This is called a remux.

A remux runs at read speed — a 2 GB file finishes in seconds, not minutes. And because there is no heavy computation involved, it can run entirely in your browser using a local MKV to MP4 converter. No install, no upload, no account. The file never leaves your device.

Unlike VLC, a dedicated remux tool handles the container rewrite correctly: audio tracks are preserved, text subtitles are converted to MP4's mov_text format, and HEVC video gets the hvc1 tag that Apple devices need. The things VLC gets wrong are exactly the things a remuxer is built to get right.

VLC conversion vs. browser-based remux

	VLC Convert/Save	Browser remux (this site)
What happens to the video	Decoded and re-compressed (H.264 + MPEG Audio)	Copied bit-for-bit into MP4 container
Quality	One generation of loss	Identical to the source
Audio reliability	Frequently drops or corrupts audio tracks	All MP4-compatible tracks preserved
Time for a 2 GB file	20–60+ minutes, CPU-bound	Seconds
Subtitle handling	Often dropped silently	Text subs converted to MP4 format automatically
Install required	Yes — desktop app	No — runs in the browser
Best for	Quick playback of any format	Turning MKV into MP4 reliably

When VLC conversion is still worth it

VLC's converter has a narrow sweet spot: quick, one-off re-encodes where you don't need fine quality control and the file is short enough that the re-encoding time is tolerable. Specifically:

Short clips under 5 minutes. The re-encode finishes fast enough that VLC's limitations barely matter.
You already have VLC and don't want another tool. For a single file where audio works and quality isn't critical, VLC gets the job done.
You need a format VLC encodes well — like a basic H.264 + AAC MP4 from a WebM source.

For anything else — long videos, files with DTS/Opus/FLAC audio, batch conversions, or situations where quality matters — use a dedicated tool. HandBrake is the best free desktop re-encoder. And if your MKV just needs to be an MP4 so your device accepts it, a browser-based remux does it in seconds with zero quality loss — no install on Mac or Windows.

Skip the re-encode and the audio bugs

Drop your MKV into the free MKV to MP4 converter — it runs entirely in your browser. No upload, no install, no account. Most files finish in seconds via lossless remux with all audio and subtitle tracks intact.