Realtime motion interpolating 60fps playback in mpv

readme.md

Realtime motion interpolating playback in mpv

Edit 2016-09: SVP now has a free (but proprietary) version of their software, which includes a GPU port of the MVTools functions, making this much less resource intense: https://www.svp-team.com/wiki/SVP:Linux (AUR)

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run this for SVP-like motion interpolation:

cd ~/.config/mpv # or ~/.mpv

wget https://gist.githubusercontent.com/phiresky/4bfcfbbd05b3c2ed8645/raw/motioninterpolation.vpy

echo 'I vf toggle format=yuv420p,vapoursynth=~~/motioninterpolation.vpy:4:4' >> input.conf

# to enable it by default
echo 'vf=format=yuv420p,vapoursynth=~~/motioninterpolation.vpy:4:4' >> mpv.conf

now press shift+i while mpv is playing a video to toggle beautiful motion vector interpolation of the video framerate to your display refresh rate.

You need mpv compiled with VapourSynth support. Not sure what distributions do this, in Arch Linux you can get mpv-git or mpv-vapoursynth (AUR) and vapoursynth-plugin-mvtools.

It should also be possible to make this work through SMPlayer.

Warning: This is CPU intensive. The settings work on a i5-2500k cpu. If it lags you will have to change some parameters, look for 2500k in the script. If your CPU is faster remove that block.

If your CPU is really fast, try removing the 'mode' parameter and changing BlockFPS to FlowFPS, this gives much better results.

See the reddit post for more information

Encoding video to a higher framerate

Run this:

vspipe --arg in_filename=input.mkv --arg display_fps=60 --y4m motioninterpolation.vpy -|ffmpeg -i - -crf 18 output.mkv

motioninterpolation.vpy

# vim: set ft=python:

# see the README at https://gist.github.com/phiresky/4bfcfbbd05b3c2ed8645
# source: https://github.com/mpv-player/mpv/issues/2149
# source: https://github.com/mpv-player/mpv/issues/566
# source: https://github.com/haasn/gentoo-conf/blob/nanodesu/home/nand/.mpv/filters/mvtools.vpy

import vapoursynth

core = vapoursynth.get_core()
# ref: http://avisynth.org.ru/mvtools/mvtools2.html#functions
# default is 400, less means interpolation will only happen when it will work well
ignore_threshold=140
# if n% of blocks change more than threshold then don't interpolate at all (default is 51%)
scene_change_percentage=15

dst_fps = display_fps
# Interpolating to fps higher than 60 is too CPU-expensive, smoothmotion can handle the rest.
# while (dst_fps > 60):
#    dst_fps /= 2

if "video_in" in globals():
    # realtime
    clip = video_in
    # Needed because clip FPS is missing
    src_fps_num = int(container_fps * 1e8)
    src_fps_den = int(1e8)
    clip = core.std.AssumeFPS(clip, fpsnum = src_fps_num, fpsden = src_fps_den)
else:
    # run with vspipe
    clip = core.ffms2.Source(source=in_filename)
    dst_fps=float(dst_fps)

# resolution in megapixels. 1080p ≈ 2MP, 720p ≈ 1MP
mpix = clip.width * clip.height / 1000000

# Skip interpolation for >1080p or 60 Hz content due to performance
if not (mpix > 2.5 or clip.fps_num/clip.fps_den > 59):
    analParams = {
        'overlap': 0,
        'search': 3,
        'truemotion': True,
        #'chrome': True,
        #'blksize':16,
        #'searchparam':1
    }
    blockParams = {
        'thscd1': ignore_threshold,
        'thscd2': int(scene_change_percentage*255/100),
        'mode': 3,
    }

    if mpix > 1.5:
        # can't handle these on Full HD with Intel i5-2500k
        # see the description of these parameters in http://avisynth.org.ru/mvtools/mvtools2.html#functions
        analParams['search'] = 0
        blockParams['mode'] = 0
        quality = 'low'
    else:
        quality = 'high'


    dst_fps_num = int(dst_fps * 1e4)
    dst_fps_den = int(1e4)
    print("Reflowing from {} fps to {} fps (quality={})".format(clip.fps_num/clip.fps_den,dst_fps_num/dst_fps_den,quality))
    
    sup  = core.mv.Super(clip, pel=2)
    bvec = core.mv.Analyse(sup, isb=True, **analParams)
    fvec = core.mv.Analyse(sup, isb=False, **analParams)
    clip = core.mv.BlockFPS(clip, sup, bvec, fvec, 
            num=dst_fps_num, den=dst_fps_den, 
            **blockParams)

clip.set_output()

It segfaults on my machine.

● Video  --vid=1                 (av1 1920x1080 23.976 fps) [default]
● Audio  --aid=1  --alang=eng    (opus 2ch 48000 Hz) [default]
○ Subs   --sid=1  --slang=en     'English' (null) [external]
○ Subs   --sid=2  --slang=en-US  'English (United States)' (null) [external]
File tags:
 Date: 20250620
 Uploader: Veritasium
 Channel_URL: https://www.youtube.com/channel/UCHnyfMqiRRG1u-2MsSQLbXA
AO: [pipewire] 48000Hz stereo 2ch floatp
VO: [gpu] 1920x1080 yuv420p
AV: 00:22:40 / 00:42:33 (53%) A-V:  0.000 Cache: 1.6s/155KBfish: Job 1, 'mpv https://www.youtube.com/wat…' terminated by signal SIGSEGV (Address boundary error)

Tested on CachyOS.

Status

Fixed by downgrading to Python to 3.11.13 and changing vapoursynth.get_core() to vapoursynth.core in the .vpy file (to adapt it for the latest versions of VapourSynth.)