Overview The movielite.vtx module provides video transition effects for creating smooth blends between graphic clips. Transitions modify clip opacity and visual effects to create professional-looking scene changes.
Available Transitions
CrossFade Smoothly blends from one clip to another by cross-fading video and audio
Dissolve Alias for CrossFade - gradually dissolves from one clip to another
BlurDissolve Blurs and fades out the first clip while the second clip fades in sharply
Key Concepts Clip Overlap Requirements Most transitions require overlapping clips to work properly:
from movielite import VideoClip, vtx # Clips MUST overlap for CrossFade/Dissolve clip1 = VideoClip( "scene1.mp4" , start = 0 , duration = 5 ) clip2 = VideoClip( "scene2.mp4" , start = 4.5 , duration = 5 ) # 0.5s overlap # Apply transition during the overlap period transition = vtx.CrossFade( duration = 0.5 ) clip1.add_transition(clip2, transition)
The overlap duration must be at least as long as the transition duration. For example, a 1-second crossfade requires at least 1 second of overlap between clips.
BlurDissolve Exception BlurDissolve is unique - it does NOT require overlapping clips:# BlurDissolve works with consecutive clips (no overlap needed) clip1 = VideoClip( "scene1.mp4" , start = 0 , duration = 5 ) clip2 = VideoClip( "scene2.mp4" , start = 5.0 , duration = 5 ) # No overlap transition = vtx.BlurDissolve( duration = 1.0 , max_blur = 21 ) clip1.add_transition(clip2, transition)
Usage Pattern All transitions follow the same application pattern:
from movielite import VideoClip, VideoWriter, vtx # 1. Create clips with proper timing clip1 = VideoClip( "scene1.mp4" , start = 0 , duration = 5 ) clip2 = VideoClip( "scene2.mp4" , start = 4.0 , duration = 5 ) # 1.0s overlap # 2. Create and apply transition transition = vtx.CrossFade( duration = 1.0 ) clip1.add_transition(clip2, transition) # 3. Write output total_duration = clip1.duration + clip2.duration - 1.0 # Account for overlap writer = VideoWriter( "output.mp4" , fps = 30 , size = clip1.size, duration = total_duration) writer.add_clips([clip1, clip2]) writer.write() clip1.close() clip2.close()
Transition Classes All transition classes inherit from the base Transition class and implement the apply() method:
CrossFade Dissolve BlurDissolve
Common Use Cases Multiple Transitions Chain multiple clips with different transitions:
clip1 = VideoClip( "scene1.mp4" , start = 0 , duration = 4 ) clip2 = VideoClip( "scene2.mp4" , start = 3.5 , duration = 4 ) # 0.5s overlap clip3 = VideoClip( "scene3.mp4" , start = 7.0 , duration = 4 ) # 0.5s overlap clip1.add_transition(clip2, vtx.CrossFade( duration = 0.5 )) clip2.add_transition(clip3, vtx.Dissolve( duration = 0.5 ))
Image Slideshow Create smooth photo slideshows:
from movielite import ImageClip, vtx images = [ ImageClip( "photo1.jpg" , start = 0 , duration = 3 ), ImageClip( "photo2.jpg" , start = 2.5 , duration = 3 ), # 0.5s overlap ImageClip( "photo3.jpg" , start = 5.0 , duration = 3 ), # 0.5s overlap ] for i in range ( len (images) - 1 ): images[i].add_transition(images[i + 1 ], vtx.CrossFade( duration = 0.5 ))
vfx - Visual effects (color, blur, etc.)VideoClip - Video clip base classGraphicClip - Base class for all visual clips 