CRITICAL GUIDELINES
Windows File Path Requirements
MANDATORY: Always Use Backslashes on Windows for File Paths
When using Edit or Write tools on Windows, you MUST use backslashes (\) in file paths, NOT forward slashes (/).
Documentation Guidelines
NEVER create new documentation files unless explicitly requested by the user.
FFmpeg Animation Timing Reference
This skill is the authoritative answer to "what unit is this timing value in?" and "how long should this animation be?" for FFmpeg filters and ASS/SSA subtitles. Use it whenever animation, transition, caption, or sync timing is in play.
Quick Reference Card
| Context |
Unit |
Example |
| FFmpeg filters (fade, xfade, drawtext) |
Seconds |
duration=1.5 |
FFmpeg zoompan d= parameter |
Frames |
d=150 (150 frames) |
FFmpeg time variable t |
Seconds |
enable='gte(t,2)' |
ASS karaoke tags (\k, \kf, \ko) |
Centiseconds |
{\k100} = 1 second |
ASS animation tags (\t, \fad, \move) |
Milliseconds |
\t(0,500,...) = 0.5s |
| ASS dialogue timestamps |
H:MM:SS.CC |
0:00:05.50 |
CRITICAL: ASS Has TWO Different Time Units!
This is the most common source of confusion in subtitle animations. Karaoke tags use centiseconds; everything else (animation, fade, move) uses milliseconds. Mixing them up causes animations to run 10x too fast or 10x too slow.
ASS/SSA Time Unit Disambiguation
| Tag Type |
Unit |
Conversion |
Example |
Karaoke tags (\k, \kf, \ko, \K) |
Centiseconds (1/100s) |
x 100 |
{\k50} = 0.5 seconds |
Animation tags (\t) |
Milliseconds (1/1000s) |
x 1000 |
\t(0,200,...) = 0.2 seconds |
Fade tags (\fad) |
Milliseconds |
x 1000 |
\fad(300,0) = 0.3s fade in |
Move tags (\move) |
Milliseconds |
x 1000 |
\move(x1,y1,x2,y2,0,500) = 0.5s |
| Dialogue timestamps |
H:MM:SS.CC |
Centiseconds |
0:00:01.50 = 1.5 seconds |
Same Duration, Different Units
; Both animations last 0.5 seconds but use DIFFERENT UNITS:
; Karaoke: 50 CENTISECONDS = 0.5 seconds
{\k50}Word
; Animation: 500 MILLISECONDS = 0.5 seconds
{\t(0,500,\fscx120)}Word
For full karaoke, fade, and move examples plus centisecond/millisecond conversion tables, see references/copy-paste-patterns.md.
FFmpeg Time Units (Cheat Sheet)
Most FFmpeg filters take seconds (floating point). The big exception is zoompan d=, which is in frames.
| Filter / Context |
Parameter |
Unit |
fade / afade |
d, st |
Seconds |
xfade / acrossfade |
duration, offset |
Seconds |
drawtext |
t variable, enable |
Seconds |
zoompan |
d |
Frames |
zoompan |
t variable inside z= |
Seconds |
trim |
start, end |
Seconds |
fps |
fps |
Frames/second |
Zoompan Duration: Frames, Not Seconds
# d= is FRAMES. For a 2-second zoom:
# 30fps: d=60 (60 frames / 30fps)
# 60fps: d=120 (120 frames / 60fps)
# Formula: frames = seconds * fps
ffmpeg -i input.mp4 -vf "zoompan=z='1.2':d=60:s=1080x1920" output.mp4
For viral-style hooks always use d=1 (per-frame processing) and gate the effect with a time conditional like if(lt(t,0.5),...). Setting d=60 would freeze the rest of the video. Full hook formulas and platform-specific zoom parameters are in references/optimal-durations.md.
Core Workflow
- Identify the context (FFmpeg filter vs ASS karaoke vs ASS animation vs dialogue timestamp) and read the Quick Reference Card to confirm the unit.
- Pick a target duration based on perception (
references/optimal-durations.md) and platform pacing (references/platform-and-sync.md).
- Snap to frame boundaries if the value is short (<300ms) using the frame-safe table in
references/platform-and-sync.md.
- Choose an easing curve when the motion needs polish (
references/easing-and-springs.md).
- Validate against perception thresholds and sync tolerances so animations don't fall under the flicker threshold or break lip sync.
- Copy the matching pattern from
references/copy-paste-patterns.md and adapt parameters.
Activation Guidance
Pull the right reference based on the question:
| Question shape |
Load |
| "How long should this caption / transition / hook be?" |
references/optimal-durations.md |
| "Why does my caption feel too fast / fail WCAG?" |
references/caption-readability.md |
| "Does this work for TikTok / Shorts / Reels / broadcast?" |
references/platform-and-sync.md |
| "Is my lip sync / beat sync within tolerance?" |
references/platform-and-sync.md |
| "Will this duration look smooth at 30fps / 60fps?" |
references/platform-and-sync.md |
| "Which easing curve / spring should I use?" |
references/easing-and-springs.md |
| "Give me a ready-to-paste timing snippet." |
references/copy-paste-patterns.md |
Quick Duration Cheat Sheet
| Duration |
Use For |
| 50-100ms |
Glitch, flash |
| 100-200ms |
Quick UI feedback |
| 200-300ms |
Standard animation |
| 300-500ms |
Smooth transition |
| 500-800ms |
Noticeable movement |
| 800-1500ms |
Dramatic effect |
| 1.5-3s |
Caption display |
| 3-5s |
Long text reading |
Hard floors: WCAG minimum caption duration is 1.5s. Minimum perceivable animation is ~67ms at 30fps, ~33ms at 60fps. Lip sync tolerance is +/-80ms (target +/-40ms).
Reference Map
In-skill references (load on demand):
references/optimal-durations.md - Human perception thresholds, recommended durations for text animations, video transitions, hook effects, karaoke; viral-video 1.3s attention threshold and platform-specific zoom parameters/hook formulas.references/caption-readability.md - Reading speed standards (WPM), caption duration formula, Python implementation, WCAG 2.2 accessibility requirements.references/platform-and-sync.md - TikTok / YouTube Shorts / Instagram Reels / Broadcast timing profiles, audio-video sync tolerances (lip sync, music, karaoke, SFX), frame rate precision and frame-safe duration table.references/easing-and-springs.md - Material Design timing, FFmpeg easing expressions, complete easing formulas (linear, quadratic, cubic, exponential, sine, circular, elastic, bounce, back), spring physics (mass-spring-damper), oscillation/wave/Lissajous formulas, pseudo-random noise, jitter/shake, fade/scale/position/rotation cookbook, biological rhythms, sources.references/copy-paste-patterns.md - Ready-to-paste FFmpeg and ASS timing snippets, frame rate conversion table, zoompan duration calculation.
Related Skills
ffmpeg-karaoke-animated-text - Karaoke subtitle creationviral-video-animated-captions - CapCut-style animationsffmpeg-transitions-effects - Video transitionsviral-video-hook-templates - Hook timing patternsffmpeg-captions-subtitles - Subtitle fundamentals
1---2name: ffmpeg-animation-timing-reference3description: Definitive reference for FFmpeg and ASS/SSA animation timing units, optimal durations, and best practices. PROACTIVELY activate for: (1) Animation timing questions, (2) ASS subtitle timing, (3) Karaoke timing tags, (4) Caption duration calculation, (5) Transition duration selection, (6) Fade/zoom timing, (7) Frame rate considerations, (8) Platform-specific timing (TikTok/Shorts/Reels), (9) Readability formulas, (10) Audio-video sync tolerances. Provides: Complete time unit reference tables, optimal duration guidelines, psychology-based timing recommendations, caption readability formulas, and platform-specific timing profiles.4---5
6## CRITICAL GUIDELINES
7
8### Windows File Path Requirements
9
10**MANDATORY: Always Use Backslashes on Windows for File Paths**
11
12When using Edit or Write tools on Windows, you MUST use backslashes (`\`) in file paths, NOT forward slashes (`/`).
13
14### Documentation Guidelines
15
16**NEVER create new documentation files unless explicitly requested by the user.**
17
18---
19
20# FFmpeg Animation Timing Reference
21
22This skill is the authoritative answer to "what unit is this timing value in?" and "how long should this animation be?" for FFmpeg filters and ASS/SSA subtitles. Use it whenever animation, transition, caption, or sync timing is in play.
23
24## Quick Reference Card
25
26| Context | Unit | Example |
27|---------|------|---------|
28| FFmpeg filters (fade, xfade, drawtext) | **Seconds** | `duration=1.5` |
29| FFmpeg `zoompan` `d=` parameter | **Frames** | `d=150` (150 frames) |
30| FFmpeg time variable `t` | **Seconds** | `enable='gte(t,2)'` |
31| ASS karaoke tags (`\k`, `\kf`, `\ko`) | **Centiseconds** | `{\k100}` = 1 second |
32| ASS animation tags (`\t`, `\fad`, `\move`) | **Milliseconds** | `\t(0,500,...)` = 0.5s |
33| ASS dialogue timestamps | **H:MM:SS.CC** | `0:00:05.50` |
34
35---
36
37## CRITICAL: ASS Has TWO Different Time Units!
38
39**This is the most common source of confusion in subtitle animations.** Karaoke tags use centiseconds; everything else (animation, fade, move) uses milliseconds. Mixing them up causes animations to run 10x too fast or 10x too slow.
40
41### ASS/SSA Time Unit Disambiguation
42
43| Tag Type | Unit | Conversion | Example |
44|----------|------|------------|---------|
45| **Karaoke tags** (`\k`, `\kf`, `\ko`, `\K`) | **Centiseconds** (1/100s) | x 100 | `{\k50}` = 0.5 seconds |
46| **Animation tags** (`\t`) | **Milliseconds** (1/1000s) | x 1000 | `\t(0,200,...)` = 0.2 seconds |
47| **Fade tags** (`\fad`) | **Milliseconds** | x 1000 | `\fad(300,0)` = 0.3s fade in |
48| **Move tags** (`\move`) | **Milliseconds** | x 1000 | `\move(x1,y1,x2,y2,0,500)` = 0.5s |
49| **Dialogue timestamps** | **H:MM:SS.CC** | Centiseconds | `0:00:01.50` = 1.5 seconds |
50
51### Same Duration, Different Units
52
53```ass
54; Both animations last 0.5 seconds but use DIFFERENT UNITS:
55
56; Karaoke: 50 CENTISECONDS = 0.5 seconds
57{\k50}Word
58
59; Animation: 500 MILLISECONDS = 0.5 seconds
60{\t(0,500,\fscx120)}Word
61```
62
63For full karaoke, fade, and move examples plus centisecond/millisecond conversion tables, see `references/copy-paste-patterns.md`.
64
65---
66
67## FFmpeg Time Units (Cheat Sheet)
68
69Most FFmpeg filters take seconds (floating point). The big exception is `zoompan d=`, which is in **frames**.
70
71| Filter / Context | Parameter | Unit |
72|------------------|-----------|------|
73| `fade` / `afade` | `d`, `st` | Seconds |
74| `xfade` / `acrossfade` | `duration`, `offset` | Seconds |
75| `drawtext` | `t` variable, `enable` | Seconds |
76| `zoompan` | `d` | **Frames** |
77| `zoompan` | `t` variable inside `z=` | Seconds |
78| `trim` | `start`, `end` | Seconds |
79| `fps` | `fps` | Frames/second |
80
81### Zoompan Duration: Frames, Not Seconds
82
83```bash
84# d= is FRAMES. For a 2-second zoom:
85# 30fps: d=60 (60 frames / 30fps)
86# 60fps: d=120 (120 frames / 60fps)
87# Formula: frames = seconds * fps
88ffmpeg -i input.mp4 -vf "zoompan=z='1.2':d=60:s=1080x1920" output.mp4
89```
90
91For viral-style hooks always use `d=1` (per-frame processing) and gate the effect with a time conditional like `if(lt(t,0.5),...)`. Setting `d=60` would freeze the rest of the video. Full hook formulas and platform-specific zoom parameters are in `references/optimal-durations.md`.
92
93---
94
95## Core Workflow
96
971. **Identify the context** (FFmpeg filter vs ASS karaoke vs ASS animation vs dialogue timestamp) and read the Quick Reference Card to confirm the unit.
982. **Pick a target duration** based on perception (`references/optimal-durations.md`) and platform pacing (`references/platform-and-sync.md`).
993. **Snap to frame boundaries** if the value is short (<300ms) using the frame-safe table in `references/platform-and-sync.md`.
1004. **Choose an easing curve** when the motion needs polish (`references/easing-and-springs.md`).
1015. **Validate against perception thresholds and sync tolerances** so animations don't fall under the flicker threshold or break lip sync.
1026. **Copy the matching pattern** from `references/copy-paste-patterns.md` and adapt parameters.
103
104## Activation Guidance
105
106Pull the right reference based on the question:
107
108| Question shape | Load |
109|----------------|------|
110| "How long should this caption / transition / hook be?" | `references/optimal-durations.md` |
111| "Why does my caption feel too fast / fail WCAG?" | `references/caption-readability.md` |
112| "Does this work for TikTok / Shorts / Reels / broadcast?" | `references/platform-and-sync.md` |
113| "Is my lip sync / beat sync within tolerance?" | `references/platform-and-sync.md` |
114| "Will this duration look smooth at 30fps / 60fps?" | `references/platform-and-sync.md` |
115| "Which easing curve / spring should I use?" | `references/easing-and-springs.md` |
116| "Give me a ready-to-paste timing snippet." | `references/copy-paste-patterns.md` |
117
118## Quick Duration Cheat Sheet
119
120| Duration | Use For |
121|----------|---------|
122| 50-100ms | Glitch, flash |
123| 100-200ms | Quick UI feedback |
124| 200-300ms | Standard animation |
125| 300-500ms | Smooth transition |
126| 500-800ms | Noticeable movement |
127| 800-1500ms | Dramatic effect |
128| 1.5-3s | Caption display |
129| 3-5s | Long text reading |
130
131Hard floors: WCAG minimum caption duration is 1.5s. Minimum perceivable animation is ~67ms at 30fps, ~33ms at 60fps. Lip sync tolerance is +/-80ms (target +/-40ms).
132
133---
134
135## Reference Map
136
137In-skill references (load on demand):
138
139- `references/optimal-durations.md` - Human perception thresholds, recommended durations for text animations, video transitions, hook effects, karaoke; viral-video 1.3s attention threshold and platform-specific zoom parameters/hook formulas.
140- `references/caption-readability.md` - Reading speed standards (WPM), caption duration formula, Python implementation, WCAG 2.2 accessibility requirements.
141- `references/platform-and-sync.md` - TikTok / YouTube Shorts / Instagram Reels / Broadcast timing profiles, audio-video sync tolerances (lip sync, music, karaoke, SFX), frame rate precision and frame-safe duration table.
142- `references/easing-and-springs.md` - Material Design timing, FFmpeg easing expressions, complete easing formulas (linear, quadratic, cubic, exponential, sine, circular, elastic, bounce, back), spring physics (mass-spring-damper), oscillation/wave/Lissajous formulas, pseudo-random noise, jitter/shake, fade/scale/position/rotation cookbook, biological rhythms, sources.
143- `references/copy-paste-patterns.md` - Ready-to-paste FFmpeg and ASS timing snippets, frame rate conversion table, zoompan duration calculation.
144
145## Related Skills
146
147- `ffmpeg-karaoke-animated-text` - Karaoke subtitle creation
148- `viral-video-animated-captions` - CapCut-style animations
149- `ffmpeg-transitions-effects` - Video transitions
150- `viral-video-hook-templates` - Hook timing patterns
151- `ffmpeg-captions-subtitles` - Subtitle fundamentals
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