TEncoder Video Converter (Windows)

TEncoder Video Converter is a great video converter intended for Windows systems. It is free, open source and supports all major video file formats: not only MP4 and AVI, but also MKV, WMV, MPEG and DVD without copy protection. It is also available in a portable version that does not require installations in order to work (which is the one I recommend you try). What more could you want?
To download TEncoder Video Converter on your PC, connected to the SourceForge page hosting the application, select the folder relating to the latest version of the software available for download (at the time of writing this guide is the 4.5.8) and click on the item TEncoder (xx) portable_32bit.exe or on the item TEncoder (xx) portable_64bit.exe to download the 32-bit or 64-bit version of the converter, respectively.
Once the download is complete, start the executable you just downloaded, click on the button [...], choose the folder in which to extract all the TEncoder Video Converter files and press on Extract to complete the operation. Then, go to the folder where you extracted the program files, double click on the icon TEncoder.exe and drag the MP4 videos to convert to AVI into the window that pops up.
Wait a few moments for the videos to be imported into TEncoder Video Converter and make sure that in the drop-down menus Video codec e Container the items are selected respectively XviD ed REVIEWS. At this point, click on the button Video and Audio options and adjust the software settings in this way.
- Video bitrate - 768 kbps or higher (the higher the bitrate, the higher the video quality, but the file weight also increases).
- Common sizes - original (in order to maintain the resolution of the starting video).
- FPS - same as source (in order to keep the framerate of the starting video).
- Aspect Ratio - keep (in order to keep the original video aspect ratio).
- Audio bitrate - 192 kbps or higher.
Ad operazione completata, click your Close, select the folder to save the output videos by clicking the button KATEGORIEN which is located at the bottom right and starts the conversion of MP4 files to AVI by pressing the button Encode (in alto to destra).
Video to Video Converter (Windows)

If TEncoder Video Converter seems a little too cumbersome to use, you can convert MP4 to AVI also with Video to Video Converter, another free converter for Windows that can process all major video file formats. It is also available in a portable version but, unlike the software examined previously, it is not open source.
To download Video to Video Converter on your PC, connect to its official website and click the button first Download and then on the voice Click here to download ZIP archive. Then wait for the download to complete, open the zip archive that contains the program and extract the contents to any folder.
At this point, launch the executable vv.exeselect l 'cittàn from the drop-down menu to choose the language and click on OK. Then drag the MP4 files to be transformed into AVI in the window that opens, select the icon REVIEWS from the box that appears and click on OK.
Finally, set the fields Quality e Video size of the right sidebar up Same as sourcee Original (so that the output videos have the same resolution and the same quality as the source ones) and presses on first OK and then Converted to start converting files.
If you want, you can also change the output video destination folder by clicking on the icon gialla poster which is located at the bottom right.
Adapter (Mac OS X / Windows)

Adapter is a free converter based on FFMPEG (well-known open source video processing software) available for Windows and OS X. If you are using a Mac I highly recommend that you try it as it is at least a couple of inches above most free converters. available on the App Store.
To download it to your computer, connect to its website and click on the button Download. Then open the package dmg that contains the software and drag its icon into the folder Applications of OS X to install it on OS X.
At the end of the procedure, start Adapter through its icon in the Launchpad and click on the button Continue to start the download and installation of the FFMPEG files necessary for the program to function. The operation should only take a few seconds.
Now, drag the MP4 videos to be transformed into AVI in the Adapter window, expand the drop-down menu at the bottom and select the item Video> General> Custom AVI from the latter. Then press the icon ofgear and adjust the software settings so that the voice Resolution both Same as source is that Quality su High o Very high. In this way you will get videos with the same resolution and the same quality level as the starting videos. Finally, press the button Convert and wait for the video conversion to finish.
How to convert MP4 to AVI