Overview MovieLite provides three categories of effects:
VFX (Visual Effects) - Effects for GraphicClip instances (video, image, text)AFX (Audio Effects) - Effects for AudioClip instancesVTX (Video Transitions) - Transitions between two GraphicClip instances
All effects use a consistent API: create the effect, then apply it to a clip.
Visual Effects (VFX) Visual effects modify how graphic clips appear. They work by adding transformations to the clip’s rendering pipeline.
Importing VFX from movielite import vfx from movielite import VideoClip, ImageClip
Fade Effects FadeIn Gradually increases opacity from 0 to the clip’s original opacity.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.FadeIn( duration = 2.0 )) # Fades in over first 2 seconds
FadeOut Gradually decreases opacity to 0 at the end of the clip.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.FadeOut( duration = 1.5 )) # Fades out over last 1.5 seconds
Combining Fades clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.FadeIn( 2.0 )).add_effect(vfx.FadeOut( 2.0 )) # Fades in for 2s, fades out for 2s
Source: src/movielite/vfx/fade.py:1
Blur Effects Blur (Static) Applies constant Gaussian blur.
clip = ImageClip( "photo.png" , start = 0 , duration = 5 ) clip.add_effect(vfx.Blur( intensity = 15.0 )) # intensity must be odd number >= 1 (kernel size)
Blur (Animated) Blur increases from 0 to maximum over time.
clip = ImageClip( "photo.png" , start = 0 , duration = 5 ) clip.add_effect(vfx.Blur( intensity = 21.0 , animated = True , duration = 3.0 )) # Blur increases over first 3 seconds
BlurIn Starts blurred and becomes sharp.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.BlurIn( duration = 2.0 , max_intensity = 25.0 )) # Starts at blur intensity 25, decreases to 0 over 2 seconds
BlurOut Starts sharp and becomes blurred at the end.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.BlurOut( duration = 2.0 , max_intensity = 25.0 )) # Last 2 seconds blur from 0 to intensity 25
Source: src/movielite/vfx/blur.py:1
Color Adjustments Brightness Adjust brightness using optimized pixel transforms (numba-compiled).
clip = VideoClip( "dark_video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.Brightness( factor = 1.3 )) # 1.0 = no change, >1.0 = brighter, <1.0 = darker
Contrast Adjust contrast around midpoint (128).
clip = ImageClip( "photo.png" , start = 0 , duration = 5 ) clip.add_effect(vfx.Contrast( factor = 1.5 )) # 1.0 = no change, >1.0 = more contrast, <1.0 = less contrast
Saturation Adjust color saturation.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.Saturation( factor = 1.5 )) # 1.0 = no change, 0.0 = grayscale, >1.0 = more saturated
Black and White Convert to grayscale.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.BlackAndWhite()) # Also available as: vfx.Grayscale()
Sepia Apply sepia tone effect.
clip = ImageClip( "old_photo.png" , start = 0 , duration = 5 ) clip.add_effect(vfx.Sepia( intensity = 1.0 )) # intensity: 0.0 = no effect, 1.0 = full sepia
Source: src/movielite/vfx/color.py:1
Zoom Effects ZoomIn Gradually scales up from smaller size.
clip = ImageClip( "photo.png" , start = 0 , duration = 5 ) clip.add_effect(vfx.ZoomIn( duration = 3.0 , from_scale = 1.0 , to_scale = 1.5 , anchor = "center" # or "top-left", "bottom-right", etc. )) # Zooms from 100% to 150% over 3 seconds
ZoomOut Gradually scales down, applied at the end of clip.
clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(vfx.ZoomOut( duration = 2.0 , from_scale = 1.5 , to_scale = 1.0 , anchor = "center" )) # Last 2 seconds: zooms from 150% to 100%
Ken Burns Effect Combines slow zoom and pan for cinematic feel.
clip = ImageClip( "landscape.png" , start = 0 , duration = 8 ) clip.add_effect(vfx.KenBurns( duration = 8.0 , # None = entire clip start_scale = 1.0 , end_scale = 1.3 , start_position = ( 0 , 0 ), end_position = ( - 100 , - 50 ) # Pan left and up )) # Smooth zoom + pan with easing
Ken Burns effect uses cubic ease-in-out for smooth, professional-looking animations.
Source: src/movielite/vfx/zoom.py:1
Anchor Points Zoom effects support various anchor points:
"center" (default)"top-left", "top-right", "bottom-left", "bottom-right""top", "bottom", "left", "right"(x, y) tuple for custom position
# Zoom from top-left corner clip.add_effect(vfx.ZoomIn( duration = 2.0 , anchor = "top-left" )) # Zoom from custom point clip.add_effect(vfx.ZoomIn( duration = 2.0 , anchor = ( 500 , 300 )))
Chaining Effects Effects can be chained to create complex transformations:
from movielite import vfx, VideoClip clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) # Chain multiple effects clip.add_effect(vfx.FadeIn( 2.0 )) \ .add_effect(vfx.Brightness( 1.2 )) \ .add_effect(vfx.Saturation( 1.3 )) \ .add_effect(vfx.FadeOut( 2.0 ))
Effects are applied in the order they’re added. Some effects (like fades) modify opacity functions, while others add frame transforms.
Custom Effects Create custom visual effects by extending GraphicEffect:
from movielite.vfx.base import GraphicEffect from movielite.core import GraphicClip import numpy as np import cv2 class Vignette ( GraphicEffect ): """Add dark vignette effect around edges.""" def __init__ ( self , intensity : float = 0.5 ): self .intensity = intensity def apply ( self , clip : GraphicClip) -> None : def vignette_transform ( frame : np.ndarray, t : float ) -> np.ndarray: h, w = frame.shape[: 2 ] # Create radial gradient center_x, center_y = w // 2 , h // 2 Y, X = np.ogrid[:h, :w] dist = np.sqrt((X - center_x) ** 2 + (Y - center_y) ** 2 ) max_dist = np.sqrt(center_x ** 2 + center_y ** 2 ) # Vignette mask vignette = 1 - (dist / max_dist) * self .intensity vignette = np.clip(vignette, 0 , 1 ) # Apply to each channel result = frame.copy() for c in range (frame.shape[ 2 ]): result[:, :, c] = (frame[:, :, c] * vignette).astype(np.uint8) return result clip.add_transform(vignette_transform) # Usage clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_effect(Vignette( intensity = 0.7 ))
Source: src/movielite/vfx/base.py:1
For color adjustments, use numba-compiled pixel transforms for better performance:
import numba from movielite.core import GraphicClip @numba.njit def red_tint ( b , g , r , a , t ): """Add red tint to each pixel.""" return ( min ( 255 , max ( 0 , int (b * 0.8 ))), min ( 255 , max ( 0 , int (g * 0.8 ))), min ( 255 , max ( 0 , int (r * 1.2 ))) ) clip = VideoClip( "video.mp4" , start = 0 , duration = 10 ) clip.add_pixel_transform(red_tint)
Pixel transforms are batched and executed efficiently using numba. Multiple transforms are applied in a single pass.
Source: src/movielite/core/graphic_clip.py:187
Audio Effects (AFX) Audio effects modify audio samples in real-time during mixing.
Importing AFX from movielite import afx from movielite import AudioClip
Fade Effects FadeIn (Audio) Gradually increases volume from 0 to the clip’s original volume.
audio = AudioClip( "music.mp3" , start = 0 , duration = 30 ) audio.add_effect(afx.FadeIn( duration = 3.0 )) # Fades in over first 3 seconds
FadeOut (Audio) Gradually decreases volume to 0 at the end.
audio = AudioClip( "music.mp3" , start = 0 , duration = 30 ) audio.add_effect(afx.FadeOut( duration = 5.0 )) # Fades out over last 5 seconds
Source: src/movielite/afx/fade.py:1
Custom Audio Effects Create custom audio effects by extending AudioEffect:
from movielite.afx.base import AudioEffect from movielite.audio import AudioClip import numpy as np class Echo ( AudioEffect ): """Add simple echo effect.""" def __init__ ( self , delay : float = 0.5 , decay : float = 0.6 ): self .delay = delay # seconds self .decay = decay # 0.0 to 1.0 def apply ( self , clip : AudioClip) -> None : def echo_transform ( samples : np.ndarray, t : float , sr : int ) -> np.ndarray: delay_samples = int ( self .delay * sr) if len (samples) < delay_samples: return samples result = samples.copy() # Add delayed version of audio result[delay_samples:] += samples[: - delay_samples] * self .decay return result clip.add_transform(echo_transform) # Usage audio = AudioClip( "voice.mp3" , start = 0 , duration = 10 ) audio.add_effect(Echo( delay = 0.3 , decay = 0.5 ))
Source: src/movielite/afx/base.py:1
Transitions (VTX) Transitions smoothly blend between two graphic clips. They require clips to overlap in time.
Importing VTX from movielite import vtx from movielite import VideoClip, ImageClip
CrossFade Blends from one clip to another. The first clip fades out while the second fades in.
clip1 = VideoClip( "video1.mp4" , start = 0 , duration = 10 ) clip2 = VideoClip( "video2.mp4" , start = 9 , duration = 10 ) # Create 1-second crossfade clip1.add_transition(clip2, vtx.CrossFade( duration = 1.0 )) # Clips must overlap by at least the transition duration # clip1 ends at 10s, clip2 starts at 9s -> 1s overlap ✓
Transitions require clips to overlap. The overlap must be at least as long as the transition duration.
Audio Crossfade If both clips are VideoClip instances with audio, CrossFade automatically applies crossfade to audio tracks:
video1 = VideoClip( "clip1.mp4" , start = 0 , duration = 10 ) video2 = VideoClip( "clip2.mp4" , start = 9 , duration = 10 ) video1.add_transition(video2, vtx.CrossFade( duration = 1.0 )) # Both video AND audio crossfade over 1 second
Source: src/movielite/vtx/crossfade.py:1
Transition Validation Transitions validate clip ordering and overlap:
clip1 = VideoClip( "video1.mp4" , start = 0 , duration = 5 ) clip2 = VideoClip( "video2.mp4" , start = 8 , duration = 5 ) # Gap: 5s to 8s clip1.add_transition(clip2, vtx.CrossFade( 1.0 )) # Raises ValueError: "Clips do not overlap"
Source: src/movielite/vtx/base.py:1
Pixel Transforms Use numba-compiled pixel transforms (add_pixel_transform) for color adjustments. They’re batched and executed in a single pass.
Frame Transforms Frame transforms (add_transform) are applied sequentially. Each transform receives the output of the previous one.
Opacity Effects Fade effects modify the opacity function, which is lightweight. Multiple fades can be combined efficiently.
Audio Effects Audio effects process samples in chunks (10-second buffers), keeping memory usage low even for long audio.
Complete Example from movielite import ( VideoWriter, VideoClip, ImageClip, TextClip, vfx, afx, vtx, VideoQuality ) from pictex import Canvas # Create clips with effects intro = VideoClip( "intro.mp4" , start = 0 , duration = 5 ) intro.add_effect(vfx.FadeIn( 1.0 )) \ .add_effect(vfx.Brightness( 1.1 )) \ .add_effect(vfx.Saturation( 1.2 )) intro.audio.add_effect(afx.FadeIn( 1.0 )) title = TextClip( "My Video" , start = 4.5 , duration = 3 , canvas = Canvas().font_size( 80 ).color( "white" ) ) title.set_position(( 100 , 100 )) title.add_effect(vfx.FadeIn( 0.5 )).add_effect(vfx.FadeOut( 0.5 )) main = VideoClip( "main.mp4" , start = 7 , duration = 30 ) main.add_effect(vfx.KenBurns( duration = 30 , start_scale = 1.0 , end_scale = 1.2 , start_position = ( 0 , 0 ), end_position = ( - 50 , - 30 ) )) outro = ImageClip( "outro.png" , start = 36.5 , duration = 5 ) outro.add_effect(vfx.FadeIn( 0.5 )) \ .add_effect(vfx.Sepia( 0.8 )) \ .add_effect(vfx.FadeOut( 1.0 )) # Add crossfade transitions intro.add_transition(title, vtx.CrossFade( 0.5 )) main.add_transition(outro, vtx.CrossFade( 0.5 )) # Background music music = AudioClip( "music.mp3" , start = 0 , duration = 42 ) music.set_volume( 0.3 ) music.add_effect(afx.FadeIn( 2.0 )).add_effect(afx.FadeOut( 3.0 )) # Compose writer = VideoWriter( "output.mp4" , fps = 30 , size = ( 1920 , 1080 )) writer.add_clips([intro, title, main, outro, music]) writer.write( video_quality = VideoQuality. HIGH )
Clips Learn about clip types and properties
Video Writer Composing and rendering videos
Audio Mixing Advanced audio techniques
