When comparing MPlayer vs IINA, the Slant community recommends IINA for most people. In the question“What are the best video players?” IINA is ranked 5th while MPlayer is ranked 6th. The most important reason people chose IINA is:
It's like mpv, just more user friendly GUI and more settings available via UI.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Needs no additional codecs
Everything MPlayer needs to play media files is contained within which means no outside codecs are needed.
Pro Easy shortcut keys
Quick skip ahead buttons and other shortcut keys.
Pro No bugs , no lag in the video display
Pro Works via CLI and has multiple frontends to choose from
Some of the more popular frontends include Deepin Media Player, GNOME MPlayer, KPlayer, KMPlayer, Rosa Media Player, SMPlayer and Xt7-Player.
Pro Nice theme available to choose from
Also, the video window is separate from the main window making it less cluttered while playing audio
Pro Like MPV with better GUI and settings
It's like mpv, just more user friendly GUI and more settings available via UI.
Pro Extremely stable
Extremely stable, even while still in the beta.
Pro Support for lots of codecs
Supports lots of video codecs, like mp4, mkv, etc, and lots of audio codecs including opus.
Pro Doesn't black out other displays when going full screen
It can black out other screens if you want, but out of the box it leaves your other displays alone.
Pro Runs on MPV so it's scriptable and runs any MPV script.
More information here.
Tip: if you're doing a lot of cropping and slicing of videos and you thought the new quick tools in Finder / Quicktime Player are a great improvement, try setting up IINA with slicing.lua and some keybindings for navigating your video + setting the slicing positions.
Make sure your ffmpeg command (in slicing.lua) is set to copy the original codecs and that it's using your GPU.
Pro Online subtitle searching and intelligent local subtitle matching
Pro Fully customizable keyboard, mouse, trackpad, and gesture controls
Pro Open source
Pro Powered by FFmpeg
Cons
Con Not much documentation on the use and configuration
Con Contrary to review, some media that play well in vlc does not play in mplayer
Con Doesn't support directory playback
Con Lacks a built-in visualizer
Con Unstable
May crash unexpectedly, while clicking on something in the subtitles section in the right-hand panel, for example.
Con Blacks out other displays when going full screen
