How To Change Default Audio Track In Mkv

MKVs are containers for audio, video, and more. Learn how to edit their contents quickly and easily on a Mac. Source: Nathan Alderman for iMore

Matroska is an open-source media format that takes its name from Russian nesting dolls. A unmarried MKV container file can hold multiple video and audio tracks, subtitles, and more than, making the format ideal for digitally bankroll up DVDs and Blu-rays. Information technology's fairly like shooting fish in a barrel to play MKVs with free software such as VLC and Plex. But adding to or changing a Matroska file'due south contents requires a little actress work. Follow our unproblematic guide, and with one free program and a few minutes' time, you'll have full control over what your Matroska files practise and don't contain.

Why would you alter an MKV file's contents?

If you want to rip your Blu-ray drove for backups or your personal media server, or only share videos yous've fabricated with the world, MKVs can easily bundle the high-def video, loftier-quality audio, and multiple subtitles from those discs in a single, manageable file. But some Blu-rays make weird choices when deciding how to squeeze all their content onto a given disc.

For instance, the Television receiver episode you tin watch with or without creators' commentary on your Blu-ray thespian may actually be two virtually identical files on the disc itself — one with no commentary audio, and one with only the commentary. If you're backing up that disc for your own personal library, keeping ii files wastes space and adds confusion. Y'all're better off plucking the commentary audio from 1 file and grafting information technology onto the other.

You could as well edit an MKV to add someone else's commentary to a beloved movie or testify – perhaps from a favorite podcast, comedians like Rifftrax, or a director commentary on MP3 released separately from the movie as a special bonus. You might also want to add together a new subtitle track to a video: a more authentic fan-made translation of foreign dialogue, or maybe just subtitles in a language not included on the original disc.

Is it legal to make or change MKV files?

That depends. If that MKV file contains video and audio you made yourself, yous're absolutely fine. If you're working with copies of physical media yous own, strictly for your own personal use, you probably won't incur the wrath of any movie studios or law enforcement agencies. Just if you're mucking effectually with stuff you've swiped, via download or disc rip, without kickoff paying for or owning information technology – which we emphatically do not recommend – you lot're on your own.

What do I need to edit an MKV file'southward contents on a Mac?

Obviously, you'll demand one or more than MKV files to piece of work with, along with any outside sound, video, or subtitle files you might want.
MKVToolNix. This free fix of MKV editing tools includes powerful control line versions installed and run via Concluding. But if yous're allergic to UNIX commands, the Mac-friendly GUI edition provides more than enough abilities to get most jobs done. Nosotros'll be using the GUI edition here.
VLC. This MKV-friendly open-source video player represents the fastest, easiest manner to check your work in one case you're finished.

How to add sound to an MKV file

1. Download MKVToolNix.

You'll find instructions for downloading MKVToolNix at the project's site. You tin get either the command line tools or the GUI version via Homebrew in the Last, but if y'all sympathize one-half or fewer of the words I just wrote, just take hold of the regular Mac installer instead. (Brand sure you first click the "Signature" link side by side to the download link to become and validate the installer's checksum for extra protection against viruses.)

two. Gather your files.

You'll demand at to the lowest degree two files to start with:

The MKV file to which y'all want to add your audio rail (or subtitle track, etc.). We'll call this the destination.
The MKV file from which you want to excerpt the detail in question. We'll refer to this file as the source.

Make certain you clearly label your source and destination in the Finder before yous start, so that you're non yanking whatsoever tracks out of, nor sewing them into, the wrong files. This won't affect the actual process any; it'll just help go along you, the squishy human being point of failure in this functioning, from getting confused.

Here, the files with shorter names and "Commentary" in them are the sources, while the files with longer names and episode titles are the destinations.

Organize your files properly before you start, to avoid confusion. Source: iMore

(Yes, I legally ain the discs in these examples, and I'one thousand not sharing copies of these files with anyone else. Yous'd have to be crazy to risk angering Batman.)

If you already have an isolated audio file and don't need to pull one out of some other MKV, you can follow the same process we'll outline below. Matroska supports an absurd number of video, sound, and subtitle formats. For audio, that includes everything from MP3 and AAC to the DTS and Dolby AC-3 files constitute on DVDs and Blu-rays. For subtitles, Matroska can handle the popular SRT and (forgive me in advance, only I assure yous that this is totally a real file blazon) ASS formats. Just check any program you program to use to play your MKVs to make sure that it supports these formats likewise.

3. Smoosh the files together.

Open up MKVToolNix GUI, and yous should come across something like this:

The main MKVToolNix window. Source: iMore

The diverse file(south) yous'll exist bundling into a single Matroska file appear in the "Source files" box at the top left; their commonage contents appear in the "Tracks, chapters, and tags" box just below information technology.

Drag and drop your destination file get-go and your source file second into this window:

Source files appear at the top left, with their contents below. Source: iMore

When you drag the source file in, you'll see this window popular up:

Not sure what any of this means? Good news: You don't have to know. Source: iMore

In my tests, the default option at the top of that list, "Add every bit new source files to the current multiplex settings," worked merely fine for my purposes, and likely volition for yours.

Afterward that, you'll see both files announced in the superlative left box. In the "Tracks, chapters, and tags" box, you'll meet everything in both containers — likely a video track, 1 or more audio tracks, plus chapters and subtitles, for each of the files you dragged in.

4. Pick which contents to go along or discard

Uncheck anything in the bottom left window that you don't desire included in the final file. When you do, you'll come across its entry under the "Re-create item" cavalcade heading flip from "Yes" to "No."

Uncheck any items you don't want included in the finished file. Source: iMore

If you're not sure which components are which, keep in mind that the contents are listed in the social club in which you lot dragged them into the MKVToolNix window, then the destination file's innards should appear first, followed past the source file's.

Since I wanted to add together a single audio commentary to an existing video file, I kept everything from my source file's contents checked, and unchecked everything but the audio file in question from my destination file. If you want, yous can reorder the contents by dragging the new sound file up side by side to the existing 1(due south), only y'all don't need to do so for the finished file to work correctly.

Prepare to send your reassembled team of contents to their new home. Source: iMore

That's all you need to practice! When you're set, just click the "Get-go multiplexing" button seen at the bottom of the image below.

Notifying users when it's completed a task? Feh. That's for lesser programs. Source: iMore

Y'all'll run across a pinwheel in the lower right corner of the MKVToolNix window get-go to spin, as a progress bar fills up. The programme won't make a audio or flash an alert when information technology's finished; the pinwheel merely stops spinning, and the bar is full. (If you meet a warning indicator appear, you can safely ignore information technology. In my tests, warnings had no effect on the finished file.)

A few seconds subsequently, you'll take a brand new MKV file with all the original contents, plus the file or files you added. Yous're not altering or re-compressing any of the contents — just taking them out of one box and putting them in another, in essence. So you don't demand to worry well-nigh losing any quality in the things you're moving.

Open up the new file in VLC and brand certain everything you want is there; you can go to Audio > Audio Tracks in the menubar, then select each audio rail to hear information technology as the video plays.

If you're satisfied with the final product, trash the source and destination files, rename the new combined file if you and then desire, and enjoy your improved viewing experience.

Got any MKV-tinkering tips or tricks we didn't include here? Experience free to share them in the comments below.