# Advanced Remotion Templates — Design Spec

## Summary

Extend the Remotion caption animation system with new highlight styles, segment transitions, and per-word entrance effects. Create two polished system presets ("Шортс" and "Подкаст") using the new capabilities. No new Remotion compositions — presets are style configurations within the existing `CaptionedVideo` composition.

## Context

### Current State

- Remotion service renders captions via a single `CaptionedVideo` composition
- `CaptionStyleSchema` controls all styling: text, layout, animation, background
- 4 highlight styles: `color`, `scale`, `underline`, `color_scale`
- 2 segment transitions: `fade`, `slide`, `none`
- 3 system presets seeded in DB: "Классические", "Неон", "Минимализм"
- Frontend has preset grid browser + full style editor with live preview
- Backend preset CRUD is complete with system/user preset separation

### What This Changes

- Adds 4 new highlight styles, 2 new segment transitions, 3 new animation fields
- Adds 2 new system presets targeting Shorts/Clips and Podcast content creators
- All changes are additive — existing presets and rendering continue to work unchanged

## Approach

**Extend existing schema (Approach A)** — add new enum values and fields to `CaptionAnimationStyle`. All rendering stays in the single `Captions.tsx` component. Chosen over separate compositions (too much duplication) and plugin architecture (over-engineered for 4-6 new animation types).

## Animation System Extensions

### New `highlight_style` Values

| Style | Visual Effect | Implementation |
|-------|--------------|----------------|
| `pop_in` | Each word springs from scale 0→1 when spoken | `spring()` on `transform: scale()` keyed to word start frame |
| `karaoke` | Color fills word left→right over its duration | CSS `linear-gradient` with `interpolate()` shifting stop from 0%→100% |
| `bounce` | Active word overshoots scale (1→1.15→1.0) with elastic ease | `spring({ damping: 8 })` on scale, triggers at word start |
| `glow_pulse` | Active word's text-shadow glow intensity oscillates | `interpolate()` cycling shadow blur/spread over word duration |

### New `segment_transition` Values

| Transition | Visual Effect |
|-----------|--------------|
| `zoom_in` | Old segment scales up + fades out, new segment scales 0.8→1 + fades in |
| `drop_in` | New segment drops from above with spring bounce |

### New Fields on `CaptionAnimationStyle`

| Field | Type | Default | Purpose |
|-------|------|---------|---------|
| `word_entrance` | `"none" \| "pop" \| "typewriter"` | `"none"` | How unspoken words appear. `pop`: spring from scale 0→1 at word start. `typewriter`: words become visible sequentially (no scale animation). `none`: all words in segment visible immediately. |
| `highlight_rotation_deg` | `float` (0–15) | `0` | Rotation in degrees applied to active word via `transform: rotate()` |
| `text_transform` | `"none" \| "uppercase" \| "lowercase"` | `"none"` | CSS `text-transform` applied to entire caption container |

### Backward Compatibility

All new fields have defaults that match current behavior (`word_entrance: "none"`, `highlight_rotation_deg: 0`, `text_transform: "none"`). Existing presets and inline configs continue to work without changes.

## System Presets

### Preset: "Шортс" (Shorts/Clips)

Target: Bold, high-energy captions for TikTok/Reels/Shorts vertical content.

```json
{
  "text": {
    "font_family": "Montserrat",
    "font_size": 72,
    "font_weight": 700,
    "text_color": "#FFFFFF",
    "highlight_color": "#FFE500",
    "text_stroke_width": 3,
    "text_stroke_color": "#000000",
    "text_shadow": "3px 3px 0px #000000"
  },
  "layout": {
    "vertical_position": "bottom",
    "horizontal_alignment": "center",
    "max_width_pct": 85,
    "lines_per_screen": 1,
    "padding_px": 20
  },
  "animation": {
    "highlight_style": "bounce",
    "highlight_scale": 1.15,
    "highlight_rotation_deg": 3,
    "word_entrance": "pop",
    "segment_transition": "zoom_in",
    "fade_duration_frames": 3,
    "animation_speed": 1.0,
    "text_transform": "uppercase"
  },
  "background": {
    "bg_color": "transparent",
    "bg_blur_px": 0,
    "bg_glow_color": null,
    "bg_border_radius_px": 0,
    "bg_padding_px": 0
  }
}
```

Key characteristics:
- All caps, 1 line at a time, no background box
- Words pop in at full size via spring animation
- Active word: yellow + 1.15x bounce + 3° rotation + subtle glow
- Heavy text stroke provides contrast without background
- Zoom transition between segments

### Preset: "Подкаст" (Podcast)

Target: Clean, professional captions for long-form podcast/interview content.

```json
{
  "text": {
    "font_family": "Inter",
    "font_size": 44,
    "font_weight": 400,
    "text_color": "#E0E0E0",
    "highlight_color": "#FFFFFF",
    "text_stroke_width": 0,
    "text_stroke_color": null,
    "text_shadow": "1px 1px 3px rgba(0,0,0,0.7)"
  },
  "layout": {
    "vertical_position": "bottom",
    "horizontal_alignment": "center",
    "max_width_pct": 90,
    "lines_per_screen": 2,
    "padding_px": 20
  },
  "animation": {
    "highlight_style": "karaoke",
    "highlight_scale": 1.0,
    "highlight_rotation_deg": 0,
    "word_entrance": "none",
    "segment_transition": "fade",
    "fade_duration_frames": 5,
    "animation_speed": 1.0,
    "text_transform": "none"
  },
  "background": {
    "bg_color": "rgba(0,0,0,0.5)",
    "bg_blur_px": 8,
    "bg_glow_color": null,
    "bg_border_radius_px": 12,
    "bg_padding_px": 16
  }
}
```

Key characteristics:
- Normal case, 2 lines, frosted glass background
- Karaoke wipe fills active word left→right with white
- All words visible — no entrance animation
- Subtle fade between segments
- Inter font, soft white for readability

## Changes Per Layer

### Remotion Service (`remotion_service/`)

**`server/types/CaptionStyleSchema.ts`**
- Extend `highlight_style` union: add `"pop_in" | "karaoke" | "bounce" | "glow_pulse"`
- Extend `segment_transition` union: add `"zoom_in" | "drop_in"`
- Add fields: `word_entrance`, `highlight_rotation_deg`, `text_transform` with defaults

**`src/components/Captions.tsx`** (~150 lines added)
- New rendering branches for each highlight style using `interpolate()` and `spring()`
- `word_entrance` logic: controls opacity/scale of words before their `wordStartFrame`
- `highlight_rotation_deg`: applies `transform: rotate()` on active word
- `text_transform`: CSS `text-transform` on caption container (lives in animation schema because it's applied at render time alongside animation logic)
- All animations must use Remotion primitives only — no CSS transitions, no Framer Motion
- Load `Montserrat` and `Inter` via `@remotion/google-fonts` alongside existing `Lobster` — dynamically load based on `styleConfig.text.font_family`

**No changes to:** `Root.tsx`, `Composition.tsx`, `useCaptions.ts`, server endpoints, queue, S3 logic

### Backend (`cofee_backend/`)

**`cpv3/modules/captions/schemas.py`**
- Extend `CaptionAnimationStyle` Literal types to include new values
- Add 3 new Optional fields with defaults matching current behavior

**Alembic migration**
- Seed 2 new system presets ("Шортс", "Подкаст") into `caption_presets` table with `is_system=True`, `user_id=NULL`
- Seed must be idempotent — check for existing name before inserting to avoid duplicates on re-run

**No changes to:** router, service, repository, task system, webhooks, notifications

### Frontend (`cofee_frontend/`)

**`features/project/CaptionSettingsStep/StyleEditor.tsx`**
- Add 4 new options to highlight style `<select>`
- Add 2 new options to segment transition `<select>`
- Add 3 new form fields: word_entrance `<select>`, rotation slider, text_transform `<select>`
- Update local `FormValues` type to include new literal values (it duplicates backend types)

**`features/project/CaptionSettingsStep/StylePreview.tsx`** (optional enhancement)
- Hint at karaoke effect with gradient in static preview
- Not critical — real preview is the rendered video

**No new components, no new files, no new API endpoints.**

## Data Flow

Unchanged. The existing flow handles this entirely:

1. User picks preset or edits style → `style_config` JSON
2. Submit → `POST /api/tasks/captions-generate/` with `preset_id` or inline config
3. Backend resolves config → sends to Remotion service
4. Remotion reads new fields from `styleConfig`, renders with new animation logic
5. Output → S3 → webhook → notification → frontend

## Testing

- **Remotion**: Visual testing via `bun run dev` (Remotion Studio) — verify each new animation style renders correctly with sample transcription data
- **Backend**: Existing integration tests cover preset CRUD — add test cases with new fields to verify persistence and retrieval
- **Frontend**: Existing E2E covers preset selection flow — verify new select options appear and are selectable
- **Type-check**: `bunx tsc --noEmit` in both `remotion_service/` and `cofee_frontend/`

## Out of Scope

- New Remotion compositions (only extending existing `CaptionedVideo`)
- Layout templates (split-screen, PiP, speaker labels)
- Social media overlays (progress bars, CTAs)
- Video cropping/resizing
- Preview rendering in the style editor (static CSS preview is sufficient)
