VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
FFmpeg - Open source multimedia suite for conversion, playback, profiling, and streaming.
MPV - MPV is an audio and movie player based on MPlayer and mplayer2.
HandBrake - HandBrake allows users to easily convert video files into a wide variety of different formats.
SMPlayer - SMPlayer is a free video and audio player for both Windows and Linux that allows you to play almost all media files without having to install additional codecs. Read more about SMPlayer.
Adobe Media Encoder CC - Create optimized video for any screen size and resolution with Adobe Media Encoder. Available only in Adobe Creative Cloud.