Motion interpolation or motion-compensated frame interpolation (MCFI) is a form of
video processing In electronics engineering, video processing is a particular case of signal processing, in particular image processing, which often employs video filters and where the input and output signals are video files or video streams. Video processing tec ...
in which intermediate animation frames are generated between existing ones by means of
interpolation
In the mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points.
In engineering and science, one often has a n ...
, in an attempt to make animation more fluid, to compensate for
display motion blur
Display motion blur, also called ''HDTV blur'' and ''LCD motion blur'', refers to several visual artifacts (anomalies or unintended effects affecting still or moving images) that are frequently found on modern consumer high-definition television se ...
, and for fake
slow motion
Slow motion (commonly abbreviated as slo-mo or slow-mo) is an effect in film-making whereby time appears to be slowed down. It was invented by the Austrian priest August Musger in the early 20th century. This can be accomplished through the use o ...
effects.
Hardware applications
Displays
Motion interpolation is a common, optional feature of various modern display devices such as
HDTV
High-definition television (HD or HDTV) describes a television system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since 1936; in more recent times, it refers to the g ...
s and video players, aimed at increasing perceived framerate or alleviating
display motion blur
Display motion blur, also called ''HDTV blur'' and ''LCD motion blur'', refers to several visual artifacts (anomalies or unintended effects affecting still or moving images) that are frequently found on modern consumer high-definition television se ...
, a common problem on
LCD
A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directly but in ...
flat-panel display
A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment.
Flat-panel displays are thin, lightweight, provide better li ...
s.
Difference from display framerate
A display's
framerate
Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images (frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also be ca ...
is not always equivalent to that of the content being displayed. In other words, a display capable of or operating at a high framerate does not necessarily mean that it can or must perform motion interpolation. For example, a TV running at 120 Hz and displaying 24 FPS content will simply display each content frame for five of the 120 display frames per second. This has no effect on the picture other than eliminating the need for
3:2 pulldown and thus film
judder
Telecine ( or ) is the process of transferring film into video and is performed in a color suite. The term is also used to refer to the equipment used in the post-production process.
Telecine enables a motion picture, captured originally on ...
as a matter of course (since 120 is evenly divisible by 24). Eliminating judder results in motion that is less "jumpy" and which matches that of a
theater projector. Motion interpolation can be used to reduce judder, but it is not required in order to do so.
Relationship to advertised display framerate
The advertised frame-rate of a specific display may refer to either the maximum number of content frames which may be displayed per second, or the number of times the display is
refreshed in some way, irrespective of content. In the latter case, the actual presence or strength of any motion interpolation option may vary. In addition, the ability of a display to show content at a specific framerate does not mean that display is capable of accepting content running at that rate; most consumer displays above 60 Hz do not accept a higher frequency
signal
In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
, but rather use the extra frame capability to eliminate judder, reduce
ghosting, or create interpolated frames.
As an example, a TV may be advertised as "240 Hz", which would mean one of two things:
# The TV can natively display 240 frames per second, and perform advanced motion interpolation which inserts between 2 and 8 new frames between existing ones (for content running at 60 FPS to 24 FPS, respectively). For
active 3D, this framerate would be halved.
# The TV is natively only capable of displaying 120 frames per second, and basic motion interpolation which inserts between 1 and 4 new frames between existing ones. Typically the only difference from a "120 Hz" TV in this case is the addition of a
strobing backlight
Display motion blur, also called ''HDTV blur'' and ''LCD motion blur'', refers to several visual artifacts (anomalies or unintended effects affecting still or moving images) that are frequently found on modern consumer high-definition television se ...
, which
flickers on and off at 240 Hz, once after every 120 Hz frame. The intent of a strobing backlight is to increase the apparent
response rate and thus reduce ghosting, which results in smoother motion overall. However, this technique has nothing to do with actual framerate. For active 3D, this framerate is halved, and no motion interpolation or pulldown functionality is typically provided. 600 Hz is an oft-advertised figure for
plasma TV
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood plas ...
s, and while technically correct, it only refers to an inter-frame response time of 1.6 milliseconds. This can significantly reduce ghosting and thus improve motion quality, but is unrelated to interpolation and content framerate. There are no consumer films shot at 600 frames per second, nor any
TV processors capable of generating 576 interpolated frames per second.
Software applications
Video playback software
Motion interpolation features are included with several video player applications.
*
WinDVD
WinDVD (owned by Corel Corporation which bought InterVideo in 2006) is a commercial video player and music player software for Microsoft Windows. It enables the viewing of DVD-Video movies on the user's PC. DVD-Video backups stored on hard disk ...
uses Philips'
TrimensionDNM for frame interpolation.
*
PowerDVD
CyberLink PowerDVD is a universal media player for movie discs, video files, photos and music. During 2016, PowerDVD achieved certification from the Blu-ray Disc Association (BDA) for the playback of Ultra HD Blu-ray Discs, and became the world's ...
uses TrueTheater Motion for interpolation of DVD and video files to up to 72 frame/s.
*
Splash PRO uses Mirillis Motion² technology for up to Full HD video interpolation.
* DmitriRender uses GPU-oriented frame rate conversion algorithm with native DXVA support for frame interpolation.
* Bluesky Frame Rate Converter is a DirectShow filter that can convert the frame rate using AMD Fluid Motion.
* SVP (SmoothVideo Project) comes integrated by default with
MPC-HC
Media Player Classic (MPC), Media Player Classic - Home Cinema (MPC-HC), and Media Player Classic - Black Edition (MPC-BE) are a family of free and open-source, compact, lightweight, and customizable media players for 32-bit and 64-bit Microsoft ...
; paid version can integrate with more players, including
VLC.
Video editing software
Some
video editing software
Video editing software, or a video editor is software used performing the post-production video editing of digital video sequences on a non-linear editing system. It has replaced traditional flatbed celluloid film editing tools and analog video ta ...
and
plugins offer motion interpolation effects to enhance
digitally-slowed video.
FFmpeg
FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing of vid ...
is a
free software
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...
non-interactive tool with such functionality.
Adobe After Effects
Adobe After Effects is a digital visual effects, motion graphics, and compositing application developed by Adobe Inc., and used in the post-production process of film making, video games and television production. Among other things, After Eff ...
has this in a feature called "Pixel Motion". The effects plugin "Twixtor" is available for most major video editing suites, and offers similar functionality.
Virtual reality
On October 6, 2016,
Oculus VR
Reality Labs is a business of Meta Platforms (formerly Facebook Inc.) that produces virtual reality (VR) and augmented reality (AR) hardware and software, including virtual reality headsets such as Quest, and online platforms such as Horizon W ...
announced that it would enable the use of motion interpolation on the
Oculus Rift
Oculus Rift is a discontinued line of virtual reality headsets developed and manufactured by Oculus VR, a division of Meta Platforms, released on March 28, 2016.
In 2012 Oculus initiated a Kickstarter campaign to fund the Rift's development, af ...
virtual reality headset, via the implementation of features such as
Asynchronous SpaceWarp
Asynchronous reprojection is a class of computer graphics technologies aimed ensuring a virtual reality headset's responsiveness to user motion even when the GPU isn't able to keep up with the headset's target frame rate. Reprojection involves the ...
and
Asynchronous TimeWarp
Asynchronous reprojection is a class of computer graphics technologies aimed ensuring a virtual reality headset's responsiveness to user motion even when the Graphics processing unit, GPU isn't able to keep up with the headset's target frame rate. ...
. This allowed the device to be used on computers whose specifications are not high enough to render to the headset at 90 frames per second.
Side effects
Visual artifacts
Motion interpolation on certain brands of TVs is sometimes accompanied by visual anomalies in the picture, described by CNET's David Carnoy as a "little tear or glitch" in the picture, appearing for a fraction of a second. He adds that the effect is most noticeable when the technology suddenly kicks in during a fast camera pan.
Television and display manufacturers refer to this phenomenon as a type of
digital artifact
Digital artifact in information science, is any undesired or unintended alteration in data introduced in a digital process by an involved technique and/or technology.
Digital artifact can be of any content types including text, audio, video, ...
. Due to the improvement of associated technology over time, such artifacts appear less frequently with modern consumer TVs, though they have yet to be eliminated entirely "the artifacts happens more often when the gap between frames are bigger".
Soap opera effect
As a byproduct of the perceived increase in frame rate, motion interpolation may introduce a "video" (versus "film") look. This look is commonly referred to as the "soap opera effect" (SOE), in reference to the distinctive appearance of most
broadcast television
Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals.
Analog television systems were standardized b ...
soap opera
A soap opera, or ''soap'' for short, is a typically long-running radio or television serial, frequently characterized by melodrama, ensemble casts, and sentimentality. The term "soap opera" originated from radio dramas originally being sponsored ...
s or pre 2000s
multicam sitcom
A sitcom, a portmanteau of situation comedy, or situational comedy, is a genre of comedy centered on a fixed set of characters who mostly carry over from episode to episode. Sitcoms can be contrasted with sketch comedy, where a troupe may use ne ...
s, which were typically shot using less expensive
60i video rather than film.
Many complain that the soap opera effect ruins the theatrical look of
cinematic
Cinematic describes anything related to ''cinema''. It may refer to: any movie updates, cinema nights, cinematic review
Film-related
* Cinematic cutscene, a sequence in a video game that is not interactive
* Cinematic music, original music writt ...
works, by making it appear as if the viewer is either on set or watching a
behind the scenes
In cinema, behind-the-scenes (BTS), also known as the making-of, the set, or on the set, is a type of documentary film that features the production of a film or television program. This is often referred to as the EPK (electronic press kit) vid ...
featurette
In the American film industry, a featurette is a kind of film that is shorter than a full-length feature, but longer than a short film. The term may refer to either of two types of content: a shorter film or a companion film.
Medium-length film ...
.
Almost all manufacturers provide ways to disable the feature, but because methods and terminology differ, the
UHD Alliance proposed that all televisions have a "Filmmaker Mode" button on remote controls to disable motion smoothing.
Sports viewers appreciate motion interpolation, as it reduces motion blur produced by
camera pans and
shaky camera
Shaky camera, Mekas, Jonas. "A Note on the Shaky Camera." '' Film Culture'', issues 24-27, 1962. shaky cam, jerky camera, queasy cam, run-and-gun or free camera is a cinematographic technique where stable-image techniques are purposely dispensed w ...
s, and thus yields better clarity of such images. It may also be used to increase the apparent framerate of
video game
Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This fee ...
s for a more realistic feel, although the addition of
display lag
Display lag is a phenomenon associated with most types of liquid crystal displays (LCDs) like smartphones and computers and nearly all types of high-definition televisions (HDTVs). It refers to latency, or lag between when the signal is sent to t ...
may be an undesired side effect.
This "video look" is created deliberately by the
VidFIRE
VidFIRE (an abbreviation of "video field interpolation restoration effect") is a technology intended to restore the video-like motion of footage originally shot with television cameras that have been converted to formats with telerecording as thei ...
technique to restore archive television programs that only survive as film
telerecording
Kinescope , shortened to kine , also known as telerecording in Britain, is a recording of a television program on motion picture film, directly through a lens focused on the screen of a video monitor. The process was pioneered during the 1940 ...
s.
The main differences between an artificially (interpolated) and naturally (in-camera) high framerate are that in-camera is not subject to any of the aforementioned artifacts, contains more accurate (or "true to life") image data, and requires more storage space and bandwidth, since frames are not produced in real time.
See also
*
Inbetweening
Inbetweening, also known as tweening, is a process in animation that involves creating intermediate Film frame, frames, called inbetweens, between two key frame, keyframes. The intended result is to create the illusion of movement by smoothly trans ...
*
Motion compensation
Motion compensation in computing, is an algorithmic technique used to predict a frame in a video, given the previous and/or future frames by accounting for motion of the camera and/or objects in the video. It is employed in the encoding of video d ...
*
Motion interpolation (computer graphics)
*
Flicker-free Flicker-free is a term given to video displays, primarily cathode ray tubes, operating at a high refresh rate to reduce or eliminate the perception of screen flicker. For televisions, this involves operating at a 100 Hz or 120 Hz hertz field rate ...
*
Television standards conversion
Television standards conversion is the process of changing a television transmission or recording from one video system to another.
Converting video between different numbers of lines, frame rates, and color models in video pictures is a comple ...
*
3:2 pulldown
References
{{Reflist
External links
High Frame Rate Motion Compensated Frame Interpolation in High-Definition Video ProcessingA Low Complexity Motion Compensated Frame Interpolation Method
Display technology
Video processing
Interpolation
Video
Film and video technology