Video Generator

Video Generation

Workflow Overview

1. Phase 1: Initial → Gather requirements, STOP for user confirmation
2. Phase 2: Global Definitions → Define style, characters, voices, BGM (text only, no images)
3. Phase 3: Clip Planning → Segment into clips, plan each clip, determine reference image needs
4. Phase 4: Reference Images → Generate reference images (MANDATORY before Phase 5)
5. Phase 5: Execution → Generate keyframes, videos, audio

---

Critical Rules (MUST Follow)

Before starting, memorize these non-negotiable rules:

1. [PHASE 1 STOP] MUST ask questions to gather information. DO NOT assume or guess missing details—always ask the user. Never proceed without explicit user confirmation.

1. [DETAILED VIDEO PROMPT] Video prompts must include detailed transition_description (2-4 sentences). One-line prompts are insufficient.

1. [KEYFRAME DIFFERENCE] Last keyframe must show interpolatable change from first keyframe: subject position/pose, subject state (open/close, appear/disappear), or composition change. Subtle-only changes (lighting, background) while subject stays static cause unnatural video motion.

1. [PHASE 4 MANDATORY] MUST generate reference images before keyframes. Never skip Phase 4.

1. [ASPECT RATIO] ALL keyframes must use 16:9 or 9:16, and must be upright (not rotated). Never generate 1:1 or other ratios.

1. [NO TTS FOR ON-SCREEN] Never use TTS for on-screen dialogue or singing. Video model generates audio with lip sync.

1. [NARRATION CLIP BY CLIP] Generate off-screen narration separately for each clip, not all at once.

1. [AUDIO MIXING] When combining audio tracks (video audio, narration, BGM), preserve ALL tracks—overlay, never replace. Narration must be clearly audible and maintain consistent volume across all clips.

---

Image Generation Tools

| Tool | Use When | |------|----------| | generate_image | Create new images (with or without references) | | generate_image_variation | Edit existing images |

---

Phase 1: Initial

Gather Information

| Field | Description | |-------|-------------| | Purpose | Goal and target audience | | Narrative arc | Story structure and key points | | Duration | Total length in seconds | | Aspect ratio | 16:9 or 9:16 only | | Visual style | Sub-genre aesthetic (e.g., "Makoto Shinkai anime", "Pixar 3D") | | Reference materials | Reference videos, images, brand guidelines | | Language | For dialogue and narration | | Recurring elements | Characters/objects with appearance descriptions | | Dialogue/singing needs | On-screen character audio | | Narration needs | Off-screen narrator (gender, tone, pace) |

Five-Dimension Expert Framework

Use these perspectives to guide your questions:

| Dimension | Expert Role | Key Questions | |-----------|-------------|---------------| | Strategy & Audience | Creative Director | Who is this for? What's the goal? What action should viewers take? | | Narrative & Structure | Screenwriter | What's the story? Key moments? Emotional arc? | | Visual Style | Director + Art Director | What look and feel? Reference videos/images? Color mood? | | Shot Execution | Cinematographer | Any specific shots in mind? Product hero shots needed? | | Sound Design | Sound Designer | Voiceover? Music mood? Dialogue? Sound effects? |

Ask questions across all dimensions. Prioritize based on user's initial description.

> [MANDATORY STOP - DO NOT PROCEED WITHOUT USER CONFIRMATION] > Summarize gathered information and wait for user confirmation before Phase 2.

---

Phase 2: Global Definitions (Text Only)

Visual Style Specification

Define these 4 dimensions (applied to primary reference images in Phase 4):

| Dimension | Example Values | |-----------|----------------| | Sub-genre | Makoto Shinkai anime, Pixar 3D, cyberpunk noir | | Rendering + Line | 2D hand-drawn with thick outlines, 3D cel-shading | | Color + Lighting | High saturation neon, soft diffused natural light | | Detail density | Minimalist, highly detailed backgrounds |

Example specification:

Sub-genre: Cyberpunk anime
Rendering + Line: 2D digital painting, thin glowing outlines
Color + Lighting: High saturation neon (pink, cyan, purple), dark backgrounds, rim lighting
Detail density: Highly detailed backgrounds, moderate character detail

Recurring Elements

For each character/object:

| Field | Description | |-------|-------------| | uniqueidentifier | Name for reference | | appearance | Text description for prompts | | outfitdescription | Clothing/accessories (characters) | | language | Spoken/sung language (if applicable) | | mechanical_properties | Physical behavior (if applicable) |

Voice Profiles

• On-screen: From character definitions (dialogue/singing)
• Off-screen narrator: name, gender, tone, pace, language

BGM Source Decision

| Scenario | BGM Source | |----------|------------| | Music video / diegetic music (visible source) | Embedded (in video prompt) | | Background mood music | Separate (Phase 5 BGM Preparation) | | No music | None |

If Separate, define: genre, instruments, tempo

---

Phase 3: Clip Planning

Segmentation Rules

• Clips: 4, 6, or 8 seconds only
• Each clip: one action, one scene

Per-Clip Specification

| Field | Values | |-------|--------| | narrativepurpose | establish / develop / climax / resolve / transition / supplementary (product shot, detail, reaction, insert, B-roll, POV) | | pacing | slow / moderate / fast | | scene | Environment description | | contentaction | Subject + action + trajectory | | transitiondescription | [REQUIRED] Detailed transition process. Must include: subject appearance, movement trajectory, state changes, existence statements. 2-4 sentences minimum. | | duration | 4 / 6 / 8 | | cameramovement | static / pan / tilt / dolly / zoom / crane / arc / handheld | | firstkeyframeframing | Shot size + angle + composition | | firstkeyframevisiblecontent | What's visible | | lastkeyframeframing | Shot size + angle + composition | | lastkeyframevisiblecontent | What's visible | | lastkeyframeeditfromfirst | yes / no (see decision table below) | | interclipboundary | continuous / scenecut | | firstkeyframereuse | yes / no | | lastkeyframerequired | yes / no | | onscreendialogue | "Name: text" or "Name: [lyrics] (style)" or None | | soundeffects | Sources or None | | bgmsource | embedded / separate / none | | bgmcue | If embedded: style, BPM, instruments. If separate: emotion, intensity | | narration_cue | Narrator text or None |

Field Dependencies

• inter_clip_boundary = continuous → next clip's first_keyframe_reuse = yes
• first_keyframe_reuse = yes → previous clip must have last_keyframe_required = yes

Keyframe Difference Requirement

When planning last_keyframe_visible_content, ensure interpolatable change from first_keyframe_visible_content:

• Subject position/pose change (movement, rotation, action)
• Subject state change (open/close, appear/disappear, expression)
• Composition change from camera movement (zoom, pan result)

> [WARNING] Avoid last keyframes with only lighting or background changes while subject remains static—this causes unnatural video motion.

Decision: lastkeyframeeditfromfirst

| Camera Movement | First & Last Keyframe Overlap? | Set to | |-----------------|-------------------------------|--------| | static, small pan/tilt, zoom | Yes (same scene area) | yes | | large pan, dolly, tracking, crane, arc | No (different area) | no |

transition_description Requirements

This field directly becomes part of the video prompt. The more detailed, the better.

Must include:

1. Subject appearance: Key visual features that must remain consistent throughout
2. Movement trajectory: How subject/camera moves through space and time
3. State changes: How objects/environment change over the duration
4. Existence statements: What is present throughout (prevents pop-in/pop-out)

Length guideline: 2-4 sentences minimum. One-line descriptions are insufficient.

transition_description Examples

| Insufficient | Sufficient | |--------------|------------| | "Open box revealing jar" | "The frosted glass jar with gold lid is inside the box from the start, hidden by the closed cream-colored lid. Elegant hands with manicured nails lift the lid upward smoothly. As the lid rises, the jar gradually comes into view - first the gold cap edge, then the full jar nestled in champagne velvet." | | "Person walks left to right" | "Woman in white dress with brown hair starts at left edge of frame, walks steadily rightward at moderate pace, maintaining upright posture, reaches right edge by end of clip." | | "Light turns on" | "Room starts in complete darkness. Light gradually increases from the ceiling fixture at center, warm yellow glow spreading outward across the wooden furniture until fully illuminated." |

Physical Consistency Check

| Movement | Constraint | |----------|------------| | Pan/Tilt/Zoom | Camera fixed, content within rotational/zoom range | | Dolly/Tracking/Crane | Content physically traversable within duration | | Arc | Subject centered in both keyframes, environment allows orbit | | Handheld | Similar to Dolly but allows irregularity | | Combined | Must satisfy ALL involved movement constraints |

Common Mistakes:

| Mistake | Correction | |---------|------------| | "Pan from corridor entrance to middle" | Use "dolly forward" | | First: room A, Last: room B | Split into two clips | | 6-second clip covering 100 meters | Extend duration or reduce distance |

[MANDATORY] Reference Image Requirements

After all clips planned, list required reference images:

| Element | Clips Using It | Required Images | |---------|----------------|-----------------| | (name) | Clip X (MS), Clip Y (CU) | Full body, Face close-up |

> [WARNING] Only generate what clips actually need. Do NOT generate all angles by default.

---

[MANDATORY] Phase 4: Reference Image Generation

MANDATORY. Do not skip to Phase 5.

Generation Order

Step 1: Primary reference (visual anchor)

• Tool: generate_image (no references)
• Prompt MUST include: Full Visual Style Specification from Phase 2 + element description
• White background
• Ends with "no text, no watermarks, no logos, no labels, no annotations"

Step 2: Additional angles/shots

• Tool: generate_image with primary reference as reference
• Prompt: New angle/shot only (style inherited from reference)
• White background
• Ends with "no text, no watermarks, no logos, no labels, no annotations"

> [WARNING] Never generate additional refs without using primary ref as reference.

---

Phase 5: Execution

Global Rules

> [CRITICAL] ALL keyframes: aspect ratio from Phase 1 (16:9 or 9:16). Never 1:1.

First Keyframe

first_keyframe_reuse = yes → Use previous clip's last keyframe (no generation)
first_keyframe_reuse = no  → Generate new keyframe

If generating first keyframe:

• [ ] Tool: generate_image
• [ ] References: Appropriate Phase 4 images
• [ ] Aspect ratio: 16:9 or 9:16
• [ ] Prompt includes:
• [ ] Visual style (sub-genre + key characteristics, brief)
• [ ] Scene environment
• [ ] Framing (shot size + angle + lens)
• [ ] Visible content
• [ ] Subject appearance + outfit
• [ ] Prompt ends with: "no text, no watermarks, no logos, no annotations"

Last Keyframe

last_keyframe_required = no  → Skip
last_keyframe_required = yes:
  last_keyframe_edit_from_first = yes → Edit mode
  last_keyframe_edit_from_first = no  → Generate mode

If EDIT mode:

• [ ] Tool: generate_image_variation
• [ ] References: [first_keyframe, Phase 4 refs...]
• [ ] Prompt: "Edit this image: [changes only]"
• [ ] Do NOT repeat unchanged elements

If GENERATE mode:

• [ ] Tool: generate_image
• [ ] References: [first_keyframe (scene ref), Phase 4 refs...]
• [ ] Aspect ratio: 16:9 or 9:16
• [ ] Prompt includes:
• [ ] Visual style (brief)
• [ ] Last keyframe framing + visible content
• [ ] Subject appearance and end state
• [ ] "Same location/environment as reference"
• [ ] Prompt ends with: "no text, no watermarks, no logos, no annotations"

Consistency Checklist (Easily Overlooked)

When generating last keyframe, verify:

• [ ] Interpolatable change: Clear difference in subject position/pose, state, or composition (not just lighting/background)
• [ ] Same lighting direction and shadows as first keyframe
• [ ] Same color temperature (warm/cool)
• [ ] Same depth of field
• [ ] Same outfit, facial features, body proportions
• [ ] Environment details consistent

Video Generation

Video prompt should be detailed. Even with keyframes, video models may drift during generation.

Prompt includes:

• [ ] Visual style (brief)
• [ ] Pacing (slow / moderate / fast)
• [ ] transition_description from Phase 3 (detailed, 2-4 sentences)
• [ ] Subject appearance (key features for consistency)
• [ ] Scene environment (brief)
• [ ] Audio (see below)

Audio in prompt:

| Type | Include | |------|---------| | On-screen dialogue | "Name says: text" with tone, language | | On-screen singing | "Name sings: [lyrics]" with style, language | | Sound effects | Source + quality | | Embedded BGM | Style, BPM, instruments, mood |

Prompt ending by bgm_source:

• embedded → (no ending, music described in prompt body)
• separate/none → End with "No background music."

Example (music video with embedded BGM):

Hatsune Miku center stage, singing in Japanese with sweet electronic voice: 
"ラララ、光の中で踊り出す", energetic J-pop at 140 BPM with synthesizer, 
crowd cheering, concert atmosphere

> [CRITICAL] Never use TTS for on-screen dialogue/singing. Video model generates audio with lip sync.

BGM Sourcing (if bgm_source = separate)

Method: Search and download from royalty-free music libraries (e.g., Pixabay, YouTube Audio Library).

[CRITICAL] Generating music with Python or any other tools is strictly prohibited. You must only use pre-existing, royalty-free tracks.

Match the downloaded music to the style defined in Phase 2.

Narration Generation (if narration exists)

> [WARNING] Generate clip by clip, not all at once.

• TTS for off-screen narrator only
• Same voice profile across all clips
• Verify audio duration fits clip duration

Audio Summary

| Type | Method | Output | |------|--------|--------| | On-screen dialogue/singing | Video model | Embedded | | Sound effects | Video model | Embedded | | Embedded BGM | Video model | Embedded | | Separate BGM | Search only | Separate track | | Narration | TTS (clip by clip) | Separate track |

Audio Mixing (Final Assembly)

When combining multiple audio sources:

| Track | Source | |-------|--------| | Video audio | Embedded in video clips (dialogue, sound effects, embedded BGM) | | Narration | TTS generated (off-screen narrator) | | Separate BGM | Searched from royalty-free source |

[CRITICAL] Mixing rules:

• Preserve ALL audio tracks—overlay, never replace one with another
• Narration must be clearly audible—not drowned out by other tracks
• Narration volume must be consistent across all clips

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: taleshagn-horushub
• Source: taleshagn-horushub/thoth
• License: MIT
• Homepage: https://horushub.com.br

Install and usage instructions live in the source repository linked above.