framesig

Find when something happens on screen — in any video, from any game or source — by its pixel signature.

framesig doesn't know what a "kill" or a "death screen" looks like — and it doesn't need to. You describe an event as a region of the frame + a colour/brightness signature in a few lines of YAML, and framesig scans the video and hands you back the timestamps where that signature appears. Red flash in the HUD, a coloured kill-feed row, a fade to black, a hard cut — same tiny config, no model, no training, no per-game code.

_{Above: framesig watching four independent regions of a synthetic clip. Boxes light up the instant their signature fires; the number is the live score.}

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Why it's useful

• Source-agnostic. It only ever reasons about pixels in a rectangle, never about the game. The same tool works on League, CS, a slideshow, or security footage.
• Declarative. Events live in YAML, not code. Tweak a region or a threshold, re-run — no recompiling, no re-scanning (see caching below).
• Cheap to re-tune. Scanning a video is the expensive part; framesig caches the raw per-frame scores, so changing a threshold is instant.
• Self-contained demo. framesig demo renders its own test clip with ffmpeg, scans it, and charts the result — no external video or model to download.

Features

• Four built-in detectors: channel_dominance, color_fraction, brightness, scene_change.
• Regions in resolution-independent fractions (or absolute pixels).
• Frame sub-sampling at a configurable rate for speed.
• JSON event output, with peak time, peak/mean score, duration and sample count per event.
• On-disk score cache keyed so that changing a threshold reuses the scan, while changing a detector invalidates it.
• A pure-OpenCV score-timeline chart renderer (no matplotlib dependency).
• Clean Python API and a framesig CLI.

Install

framesig needs only numpy, opencv-python-headless and PyYAML. (ffmpeg on your PATH is optional — it's used only to generate the sample clip in gen-sample / demo; scanning real videos does not need it.)

git clone https://github.com/ferinazumaDEV/framesig
cd framesig
python -m venv .venv && . .venv/bin/activate
pip install -e ".[dev]"

Quickstart

Render a synthetic test clip, scan it, and chart the detections in one command:

$ framesig demo
[1/3] rendering synthetic clip with ffmpeg...
[2/3] scanning for pixel signatures...
sample.mp4  640x360  15.0s  150 samples @ 10.0 fps  (scan)
7 event(s) across 4 signature(s)
  death_screen: 2
    [  2.00s ->   2.40s]  peak 1.00 @   2.00s  (5 samples)
    [  7.50s ->   7.90s]  peak 1.00 @   7.50s  (5 samples)
  kill_feed: 3
    [  4.00s ->   4.30s]  peak 0.98 @   4.00s  (4 samples)
    [  4.80s ->   5.00s]  peak 0.98 @   4.80s  (3 samples)
    [  9.40s ->   9.80s]  peak 0.98 @   9.40s  (5 samples)
  white_flash: 1
    [ 11.00s ->  11.30s]  peak 0.98 @  11.00s  (4 samples)
  scene_cut: 1
    [ 13.00s ->  13.00s]  peak 0.35 @  13.00s  (1 samples)
[3/3] rendering score-timeline chart...
done. outputs in framesig_demo/

Every event lands exactly where the clip was painted — two death flashes, three kill-feed rows, one white flash, one scene cut. The chart it writes:

Each lane is one signature: the blue curve is the raw score, the red dashed line is the threshold, the green bands are the detected events.

Usage

CLI

$ framesig gen-sample sample.mp4
wrote sample.mp4  (640x360, 15s)

$ framesig scan sample.mp4 -c examples/flash.yaml -o events.json
sample.mp4  640x360  15.0s  150 samples @ 10.0 fps  (scan)
7 event(s) across 4 signature(s)
  death_screen: 2
    [  2.00s ->   2.40s]  peak 1.00 @   2.00s  (5 samples)
    ...
wrote events.json

Run it again and the scan is served from cache — note the (cache) tag:

$ framesig scan sample.mp4 -c examples/flash.yaml -o events.json
sample.mp4  640x360  15.0s  150 samples @ 10.0 fps  (cache)

events.json (one signature shown):

{
  "video": "sample.mp4",
  "meta": { "native_fps": 30.0, "frame_count": 450, "width": 640, "height": 360,
            "sample_fps": 10.0, "step": 3, "sample_period": 0.1,
            "samples": 150, "duration": 15.0 },
  "from_cache": false,
  "events": {
    "death_screen": [
      { "signature": "death_screen", "start": 2.0, "end": 2.4, "duration": 0.5,
        "peak_t": 2.0, "peak_score": 1.0, "mean_score": 1.0, "samples": 5 }
    ]
  }
}

Handy flags: --sample-fps N (override sampling rate), --no-cache, --chart timeline.png, -q.

Config

A signature is a detector applied to a region, plus rules for turning the score timeline into discrete events:

sample_fps: 10                       # analyse ~10 frames per second of video
cache_dir: .framesig_cache           # optional; default is a .framesig_cache
                                     # folder next to the video

regions:                             # bounds are fractions of the frame by default
  hud_top:    { x: 0.00, y: 0.00, w: 1.00, h: 0.55 }
  kill_feed:  { x: 0.08, y: 0.74, w: 0.84, h: 0.18 }
  minimap:    { x: 1500, y: 800, w: 400, h: 250, unit: pixels }   # absolute pixels

signatures:
  - name: death_screen
    region: hud_top
    detector: channel_dominance      # "relative red", robust to compression
    params: { channel: red, gain: 2.0 }
    threshold: 0.30                   # score >= 0.30 counts as active
    min_duration: 0.15               # drop blips shorter than 0.15 s
    merge_gap: 0.25                   # bridge flickers up to 0.25 s apart

  - name: kill_feed
    region: kill_feed
    detector: color_fraction         # % of red pixels in the band (two HSV ranges: red wraps hue)
    params:
      hsv_low:  [0, 120, 70]
      hsv_high: [10, 255, 255]
      hsv_low2: [170, 120, 70]
      hsv_high2: [179, 255, 255]
    threshold: 0.20

See examples/flash.yaml for the full four-signature config.

Python API

from framesig import load_config, scan_video, detect_all

config = load_config("examples/flash.yaml")
result = scan_video("sample.mp4", config)      # scores get cached on disk
events = detect_all(config, result)            # applying thresholds is free

for name, evs in events.items():
    for e in evs:
        print(f"{name}: {e.peak_t:.2f}s (score {e.peak_score:.2f})")

death_screen: 2.00s (score 1.00)
death_screen: 7.50s (score 1.00)
kill_feed: 4.00s (score 0.98)
...

Detectors

detector	measures	good for	key params
channel_dominance	how much one BGR channel beats the other two	red death/kill flashes; survives compression, ignores brightness	channel, gain
color_fraction	fraction of pixels inside one or more HSV ranges	coloured HUD elements (kill feed, objective banners)	hsv_low/high, hsv_low2/high2
brightness	mean luminance	white flashes (invert: false), fades to black (invert: true)	invert
scene_change	mean absolute difference from the previous sampled frame	hard cuts, big transitions	—

framesig detectors lists them at runtime.

How it works

video ──▶ sub-sample frames ──▶ crop each region ──▶ detector score in [0,1]
                                                          │
                                            per-frame score timelines
                                                          │
                                    ┌─────────────────────┴─── cached on disk ───┐
                                    ▼                                             │
                    threshold · merge_gap · min_duration                         │
                                    ▼                                             │
                                 events ◀── re-run with new thresholds, free ◀────┘

1. Sample. The scanner walks the video once and keeps roughly sample_fps frames per second.
2. Score. Each signature crops its region and asks its detector for one number in [0, 1].
3. Cache. Those score timelines are written to .framesig_cache/, keyed by a fingerprint of the video and of the score-relevant config (sampling rate, regions, detector params) — but not thresholds. So re-tuning a threshold is a cache hit; changing a detector transparently invalidates it.
4. Detect. Thresholding turns each timeline into events: consecutive active samples become a run, nearby runs merge (merge_gap), too-short runs are dropped (min_duration).

Testing

$ pytest
88 passed

The suite includes an end-to-end test that renders the synthetic clip with ffmpeg and asserts framesig recovers exactly the events baked into it, at the right timestamps — plus unit tests for every detector, the event logic, config validation, the scanner's error paths and the cache.

Sibling tools

framesig is one of a set of small, dependency-light tools I build and maintain in the open — focused utilities that each do one job well and turn messy input into clean, structured output. If framesig fits into your pipeline, these siblings share the same engineering-first philosophy:

• The GEO Handbook — the open reference on getting content cited by AI answer engines (ChatGPT, Perplexity, Google AI Overviews, Gemini, Copilot).
• typedout — reliable structured output from any LLM: schema-validated JSON with tolerant repair and retries.
• politeclient — a polite, bulletproof HTTP client for Python: retries with backoff, per-host rate-limiting, caching, pagination.
• scaffld — scaffold fully-wired Python projects (tests, CI, pre-commit, license) from templates, with a TUI.
• Hub & writing: zentimes.es.

By ferinazumaDEV.

License

MIT — see LICENSE.

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_{Built by Fernando (@ferinazumaDEV).}