Video to Video Converter (Windows)
If you need to convert video to and from MKV format, I highly recommend using Video to Video Converter. It is a free converter for Windows that supports all major video file formats and has the advantage of being portable, ie it works without installation.
To download Video to Video Converter on your PC, connect to its website and first press the button Download and then on the link Click here to download ZIP archive. When the download is complete, open the zip archive of the program (VTV.zip), extract the contents to any folder and run the executable vv.exe.
Nella finestra che si apre, scegli l 'cittàn as the language to use in the software interface and click on OK. Next, drag the videos to convert into the program window and select one of the available output formats (eg. AVI, MKV, MP4 or a device name). If you want to convert an MKV file that contains multiple audio tracks, you can choose which track to keep in the output video by selecting one of the numbers available in the field Audio stream index (in the right sidebar).
After choosing the output format of the video to convert, click on OK; choose the folder in which to save the files using the icon folder placed at the bottom right and presses the button Converted to start the conversion process.
Adapter (Mac)
In the Mac field, as a universal converter I recommend Adapter which is completely free and - like Video to Video Converter on Windows - supports all major multimedia file formats. To download it to your computer, connect to its official website and click on the button Download.
Once the download is complete, open the package dmg which contains Adapter and drag the software icon into the folder Applications of OS X to complete its installation. Then launch Adapter, click on the button Continue and wait for the installation of FFMPEG: a free and open source software that acts as the “engine” for the converter.
When installation is complete, drag the videos to convert to the Adapter main window and select the desired output format from the drop-down menu Video: both generic file formats (eg. AVI or MP4) and specific formats for various types of devices (eg iPhone and iPad) are available.
Then click on thegear to display the Adapter settings menu and set the item Same as source in the field Resolution to keep the original resolution of the video. Then choose the option High o Very high give menu to tendin Quality (in order to avoid the annoying "checkered" effect in the output videos and have a high video quality) and presses the button Convert to start the conversion process.
HandBrake (Windows / Mac)
In conclusion, I also want to point out HandBrake. It is a free program available for Windows and Mac thanks to which it is possible to convert videos to MKV and MP4 (also optimized for iPhone, iPad and other devices) starting from all the main video file formats and, above all, they can be easily ripped the DVDs.
Unfortunately it does not support DVDs with copy protection, but by associating it with a software for decrypting diskettes it is possible to overcome even this limit. You can find detailed instructions regarding this procedure in my tutorial on how to convert DVD to MP4 (of course you can choose to convert MKV instead of MP4, the procedure to follow is the same).
How to convert MKV