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>
117 lines
3.0 KiB
Python
117 lines
3.0 KiB
Python
# /// script
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# requires-python = ">=3.10"
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# dependencies = ["numpy"]
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# ///
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"""
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@effect scanlines
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@version 1.0.0
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@author artdag
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@description
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VHS/CRT-style scan line shift. Horizontally displaces alternating lines
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to create analog video distortion. Great for retro/glitch aesthetics.
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@param amplitude float
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@range 0 100
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@default 10
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Maximum shift amount in pixels. Bind to bass for reactive glitch.
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@param frequency float
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@range 1 100
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@default 10
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Lines per cycle (affects pattern density).
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@param randomness float
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@range 0 1
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@default 0.5
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0 = regular sine pattern, 1 = fully random shifts.
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@param line_gap int
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@range 1 20
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@default 1
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Only shift every Nth line (1 = all lines).
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@param seed int
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@default 42
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Random seed for deterministic patterns.
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@state rng DeterministicRNG
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Random number generator for reproducible results.
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@example
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(effect scanlines :amplitude 20)
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@example
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;; Heavy glitch on bass
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(effect scanlines :amplitude (bind bass :range [0 50]) :randomness 0.8)
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@example
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;; Reproducible scanlines
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(effect scanlines :amplitude 30 :randomness 0.7 :seed 999)
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"""
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import numpy as np
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from pathlib import Path
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import sys
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# Import DeterministicRNG from same directory
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_effects_dir = Path(__file__).parent
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if str(_effects_dir) not in sys.path:
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sys.path.insert(0, str(_effects_dir))
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from random import DeterministicRNG
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def process_frame(frame: np.ndarray, params: dict, state: dict) -> tuple:
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"""
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Apply scan line shift to a video frame.
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Args:
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frame: Input frame as numpy array (H, W, 3) RGB uint8
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params: Effect parameters
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- amplitude: max shift in pixels (default 10)
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- frequency: lines per cycle (default 10)
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- randomness: 0-1 random vs sine (default 0.5)
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- line_gap: shift every Nth line (default 1)
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- seed: random seed (default 42)
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state: Persistent state dict
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- rng: DeterministicRNG instance
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Returns:
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Tuple of (processed_frame, new_state)
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"""
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amplitude = params.get("amplitude", 10)
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frequency = params.get("frequency", 10) or 1
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randomness = params.get("randomness", 0.5)
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line_gap = max(1, int(params.get("line_gap", 1)))
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seed = int(params.get("seed", 42))
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if state is None:
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state = {}
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# Initialize RNG
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if "rng" not in state:
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state["rng"] = DeterministicRNG(seed)
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rng = state["rng"]
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if amplitude == 0:
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return frame, state
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h, w = frame.shape[:2]
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result = frame.copy()
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for y in range(0, h, line_gap):
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# Calculate shift amount
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if randomness >= 1.0:
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shift = int(rng.uniform(-amplitude, amplitude))
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elif randomness <= 0:
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shift = int(amplitude * np.sin(2 * np.pi * y / frequency))
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else:
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sine_shift = amplitude * np.sin(2 * np.pi * y / frequency)
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rand_shift = rng.uniform(-amplitude, amplitude)
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shift = int(sine_shift * (1 - randomness) + rand_shift * randomness)
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if shift != 0:
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result[y] = np.roll(result[y], shift, axis=0)
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return result, state
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