If you want to convert MKV file to AVI being 100% sure that all your devices will "digest" it, try Adapter. It is a free software that converts all major video file formats by changing both the container and the codec.
To download it to your computer, connect to its official website and click on the button Download. Then open the dmg package you just downloaded and install Adapter on your Mac by dragging its icon to the folder Applications of OSX.
At this point, start Adapter (if an error message appears, right click on the program icon and select the item apri from the menu that appears), click on the button Continue and wait for the download of FFMPEG, an open source video processing software that acts as an "engine" for Adapter conversions. The operation will take just a few seconds.
When the FFMPEG installation is complete, drag the MKV videos you want to transform into AVI on the Adapter main screen, then expand the drop-down menu at the bottom and select the item Video> General> Custom AVI da quest'ultimo.
Next, call up the program settings panel by clicking on the icon of thegear located at the bottom right and sets the field Resolution su Same as source and the field Quality su High o Very high. This way you will get AVI files with the same resolution as the input MKV videos and a quality very close to that of the original files (keeping it identical is practically impossible in cases of video re-encoding).
If you need to convert a high definition MKV video to a standard resolution AVI video (because maybe your living room player doesn't support HD video), in the field Resolution do not choose the item Same as source: choose the item Preset and select one of the standard resolutions listed in the adjacent drop-down menu.
Finally, select the folder in which to save the output videos by clicking on the buttons Custom e KATEGORIEN present at the beginning of the Adapter sidebar and presses the button Convert to start converting MKV files to AVI. The operation may take several minutes, it all depends on the power of your computer and the length of the movies to convert.
Unfortunately Adapter does not allow you to choose the audio tracks to keep in the output videos, so if you have chosen an MKV with multiple audio tracks as input, only the primary one will be kept.
As for subtitles, it is not possible to embed them directly in AVIs. You have to extract them from MKV video and use them as external SRT files (just rename them the same way as AVI video and they should be loaded automatically by most players and devices).
extract subtitles from MKV videos, please contact MKVTools. It is a program that costs $ 5 but you can also use it for free as long as you tolerate the appearance of annoying messages that invite you to purchase the full version of the software from time to time. After you have downloaded and installed it on your Mac (by copying its icon to the folder Applications OS X), start it and press the buttons Open e Register later. Then select the MKV file from which to extract the subtitles, put the check mark next to the items relating to the subtitles to extract (subtitle) and click on your button Extract to start the operation.
iFFmpeg (trial / paid)
iFFmpeg is another FFMPEG based converter. We are therefore talking about a very valid alternative to Adapter, but with some more functions.
The software is paid, costs 17,50 euros, but is available in a free trial version that allows you to use it for a maximum number of 10 times without particular limitations. Among its most interesting functions are those to choose the audio tracks to keep in AVI files and to extract subtitles from MKV videos without resorting to external software.
To download the trial version of iFFmpeg on your computer, connect to the official website of the program and click on the button Try it free. Then open the dmg package you just downloaded, drag the iFFmpeg icon to the folder Applications of OS X and launch the program.
On its first launch, iFFmpeg will ask you to download FFMPEG (the open source software it is based on) and copy it to its main window. Then connect to this page and click on the first item located in the left sidebar (eg. FFmpeg 2.7 64bit) to start the download.
When the operation is completed, click on the button Got it of iFFmpeg, then on Demo (to start using the trial version of the application) and open the FFMPEG dmg package.
At this point, drag the named executable ffmpeg in the iFFmpeg window, confirm the installation of the software on your Mac by clicking on the buttons Use and copy to Application Support / iFFmpeg folder e OK And that's it. Now you can finally start using the converter!
Therefore, copy the MKV files to be transformed into AVI in the main window of iFFmpeg and select the item Containers> AVI Container from the drop-down menu next to their preview image. Subsequently, if you want to select the audio track to be kept in the video in AVI format, double click on the item Audio located in the right sidebar and choose the language you prefer (eg. ita for cittàn) from the drop-down menu Stream.
To extract any subtitles embedded in MKV files, instead, click on the comic located at the top right, select the subtitle track to extract from the drop-down menu that appears on the screen, set the option SRT on the menu Subtitle format e pulsing sul pulsating Extract subtitles but I will complete the operation.
Once you have adjusted all the appropriate settings (e.g. by double clicking on the item Video in the sidebar you can adjust the resolution and quality of the output file), press the button play and wait for the conversion to come to an end.
As mentioned in the initial phase of this tutorial on how to convert MKV to AVI Mac, in some cases it is possible to change the video container, that is to switch from MKV to AVI, without re-encoding the video or its audio track. This means converting the file almost instantly and avoiding any kind of quality loss.
To find out if your MKV videos are compatible with the AVI container and try to convert them without re-encoding, use Avidemux. Avidemux is a free and open source video editor compatible with all popular multimedia file formats. It allows you to cut, edit, rotate and apply various types of effects to the videos and among its functions there is also that of saving the videos directly, that is, without re-encoding their content.
To download it to your Mac, connect to its official website and click on the item FossHub placed under the Apple logo. Once the download is complete, open the dmg package that contains the program and copy its icon to the folder Applications in OS X.
When the operation is completed, right click on the Avidemux icon and select the item apri from the menu that appears, to start the converter. After that drag the MKV video to convert to AVI into the software window and set the drop down menus Video output e Audio output su Copy.
At this point, expand the drop-down menu Output format, select the voice AVI format from the latter, presses the button Configure and activate the option Avi from the window that opens. Mission accomplished! Now you just have to click on the icon floppy disk at the top left, choose a folder in which to save the video in AVI format and wait a few seconds for the output video to be generated.
To extract subtitles from MKV videos and save them as external files you can rely on MKVTools, the software I told you about earlier.How to Convert MKV to AVI Mac