mpv step backward is slow or sometimes it does not work properly whereas avidemux, djvview works

$ mpv --version      
Warning: option --softvol is deprecated and might be removed in the future (softvol is always active, and behaves as if --softvol=yes is always set).
Warning: option --softvol-max was replaced with --volume-max and might be removed in the future.
mpv 0.27.2 (C) 2000-2017 mpv/MPlayer/mplayer2 projects
 built on Wed Feb 14 14:00:12 CET 2018
ffmpeg library versions:
   libavutil       55.78.100
   libavcodec      57.107.100
   libavformat     57.83.100
   libswscale      4.8.100
   libavfilter     6.107.100
   libswresample   2.9.100
ffmpeg version: 3.4.2

I already asked this several times. BUt out of curiosity i am asking again

I was trying to play a video frame by frame using . and , keyboard shortcuts. the problem is forward is very smooth but backward is not.

I checked the same video with avidemux_qt. It has right and left keyboard shortcuts from step frame forward and backword. I observed it works very smoothly both backward and forward.

How avidemux is able to do this.

Also djv_view plays step backward very smoothly

Start by reproducing frame stepping with the reported mpv 0.27.2 version using the . and , keyboard shortcuts, comparing forward and backward behavior on the same video. The issue does not name an implementation file or test; done would require identifying and correcting the cause of slow or unreliable backward stepping and verifying both directions.