HandBrake is an open-source, multithreaded video transcoder – it compresses and converts digital media from one format to another. HandBrake can rip encrypted DVDs with libdvdcss (libdvdcss is installed with VLC media player on macOS, or AnyDVD/DVD 43 on Windows).
File Converter is a very simple tool which allows you to convert and compress one or several file(s) using the context menu in Windows Explorer.
last update 2017
ImageMagick is a software suite to create, edit, and compose bitmap images. It can read, convert and write images in a variety of formats (about 100) including GIF, JPEG, JPEG-2000, PNG, PDF, PhotoCD, TIFF, and DPX.
XMedia Recode can convert nearly all popular audio and video formats including 3GP, 3GPP, 3GPP2, AAC, AC3, AMR, ASF, AVI, AVISynth, DVD, FLAC, FLV, H.261, H.263, H.264, M4A , M1V, M2V, M4V, Matroska (MKV), MMF, MPEG-1, MPEG-2, MPEG-4, TS, TRP, MP2, MP3, MP4, MP4V, MOV, OGG, PSP...
Format Factory is a multifunctional media converter and DVD ripper. Its features include:Bundleware
Be careful during the installation: https://alternativeto.net/discussions/applications/11718/be-careful-in-the-installation/
MakeMKV is a program designed for ripping DVD and Blu-Ray disc video. It works by decrypting proprietary discs to transfer codecs from the formats VOB and M2TS into MKV, preserving the necessary data without doing any lossy codec conversion.
Open source software without any restriction - converter all formats video|audio|image professionnals codecs and standards - swiss knife tool Windows and OSX.
CloudConvert is a online file conversion tool. more than 200 different audio, video, document, ebook, archive, image, spreadsheet and presentation formats supported.