EDIT: I tried VLC as suggested by @Daniel. It was almost perfect. It was fast and user friendly. I just had to click on "Convert / Save", add the input file, select the MP4 profile, configure Video codec and Audio codec to "Keep original video / audio track", choose a destination file, and click on "Start". Otherwise, visit the VLC website and download the app. Step 1. Open VLC. Step 2. Go to "Media" > "Convert/Save" (or press the hotkeys "Ctrl + R") to open the Open Media window. Step 3. Click "Add" to add your MKV file. You can add multiple MKV files at once. Then, click "Convert/Save" at the bottom of the window. 1Upload a file. Upload the MKV file you wish to convert. Just drag & drop it onto the page, or click the blue button to choose from a folder on your device (you can also add files from Dropbox, or even straight from a YouTube URL). How do I extract audio from MP4? You can use AnyMP4 Video Converter Ultimate to extract the sound from the MP4 file. Then, launch the program and drag your MP4 files into it. Next, click the Convert All to button and choose the MP3 format as the output format from the Audio tab. In the end, just press the Convert All button to start extracting. 2. In the main menu select "Media", then "Convert / Save". 3. When the new window opens, click "Add" button, and choose your mkv file. 4. Click "Convert/Save" button. and when the new window opens, choose, "Convert", name your destination folder and file, and select the profile you want, which probably will be: Or you can use Synaptic to install it. To convert mMP4 to MKV, follow the steps below: Click on the movie like icon, to choose the MP4 file to be converted. Click on the file to select it. Make sure the output type is mkv, and then click on the green button to start the conversion. Share. As I said already when you load the mkv in handbrake it will see both internal and external subtitles. Then you can select which track you want to burn into the video and re encode to an mp4 file, all in the same operation. The encoder in VLC is not super intuitive and I don’t understand why people insist on using it. It is a green player though. Launch the program, click the Video Converter button on the main UI and then click +Video button to import the MKV files which plays in black screen on VLC or any other video players. Convert MKV to MP4. Step 2. Seconds later, click on Target Format at the bottom. You can go General Profiles > MP4 Video > OK button to convert MKV to MP4 nkaiN01.