406cc7c0c7
Add S-expression based video effects pipeline with modular effect definitions, constructs, and recipe files. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
49 lines
2.0 KiB
Common Lisp
49 lines
2.0 KiB
Common Lisp
;; Blend effect - combines two video streams
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;; Multi-input effect: uses frame-a and frame-b
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;; Params:
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;; mode - blend mode (add, multiply, screen, overlay, difference, lighten, darken, alpha)
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;; opacity - blend amount (0-1)
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;; resize-mode - how to resize frame-b to match frame-a (fit, crop, stretch)
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;; priority - which dimension takes priority (width, height)
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;; pad-color - color for padding in fit mode [r g b]
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(define-effect blend
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((mode "overlay") (opacity 0.5) (resize-mode "fit") (priority "width") (pad-color (list 0 0 0)))
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(let [a frame-a
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a-w (width a)
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a-h (height a)
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b-raw frame-b
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b-w (width b-raw)
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b-h (height b-raw)
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;; Calculate scale based on resize mode and priority
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scale-w (/ a-w b-w)
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scale-h (/ a-h b-h)
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scale (if (= resize-mode "stretch")
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1 ;; Will use explicit dimensions
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(if (= resize-mode "crop")
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(max scale-w scale-h) ;; Scale to cover, then crop
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(if (= priority "width")
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scale-w
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scale-h)))
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;; For stretch, use target dimensions directly
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new-w (if (= resize-mode "stretch") a-w (round (* b-w scale)))
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new-h (if (= resize-mode "stretch") a-h (round (* b-h scale)))
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;; Resize b
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b-resized (resize b-raw new-w new-h "linear")
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;; Handle fit (pad) or crop to exact size
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b (if (= resize-mode "crop")
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;; Crop to center
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(let [cx (/ (- new-w a-w) 2)
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cy (/ (- new-h a-h) 2)]
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(crop b-resized cx cy a-w a-h))
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(if (and (= resize-mode "fit") (or (!= new-w a-w) (!= new-h a-h)))
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;; Pad to center
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(let [pad-x (/ (- a-w new-w) 2)
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pad-y (/ (- a-h new-h) 2)
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canvas (make-image a-w a-h pad-color)]
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(paste canvas b-resized pad-x pad-y))
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b-resized))]
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(if (= mode "alpha")
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(blend-images a b opacity)
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(blend-images a (blend-mode a b mode) opacity))))
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