demodsl 2.1.2

DSL-driven automated product demo video generator

DemoDSL

DSL-driven automated product demo video generator.

Define your product demos in YAML or JSON — DemoDSL handles browser automation, voice narration, visual effects, video editing, and final export.

Demo

This video was generated automatically by DemoDSL — running demodsl run demo_site.yaml against its own documentation site.

_{▶ Click the image to watch the full demo video}

YAML config used

metadata:
  title: "DemoDSL Documentation Site Tour"

voice:
  engine: "gtts"
  voice_id: "en"

subtitle:
  enabled: true
  style: "classic"

scenarios:
  - name: "Landing Page Tour"
    url: "https://fran-cois.github.io/demodsl/"
    browser: "webkit"
    viewport: { width: 1280, height: 720 }
    avatar:
      enabled: true
      provider: "animated"
      style: "clippy"
    steps:
      - action: "navigate"
        url: "https://fran-cois.github.io/demodsl/"
        narration: "Welcome to DemoDSL..."
      - action: "scroll"
        direction: "down"
        pixels: 600
        narration: "Discover the Quick Start section..."

pipeline:
  - generate_narration: {}
  - edit_video: {}
  - mix_audio: {}
  - burn_subtitles: {}
  - composite_avatar: {}
  - optimize: { format: "mp4" }

Features

• YAML & JSON DSL — Declarative scenario definitions with steps, effects, and narration
• Browser Automation — Playwright-powered capture (Chrome, Firefox, WebKit)
• 12 Voice Providers — ElevenLabs, OpenAI, Azure, Google, AWS Polly, CosyVoice, Coqui, Piper, eSpeak, gTTS, local OpenAI-compatible, custom
• 63 Visual Effects — 33 browser JS effects + 30 post-processing effects (camera, cinematic, retro, transitions, overlays)
• Animated Avatars — 61 built-in styles with 4 providers (animated, D-ID, HeyGen, SadTalker)
• Subtitles — 6 styles (classic, TikTok, color, word-by-word, typewriter, karaoke) with Word-level timing
• Cursor Overlay — Smooth animated cursor with click effects (ripple, pulse)
• Popup Cards — Glass/dark/light/gradient cards with progressive item reveal
• Video Composition — Intro/outro, transitions, watermarks via MoviePy
• Audio Mixing — Background music with smart ducking during narration
• 11 Pipeline Stages — Chain of Responsibility with critical/optional error handling
• Remotion Renderer — React-based video composition alternative
• Cloud Deploy — S3, GCS, Azure Blob, Cloudflare R2, custom S3-compatible
• Multi-format Export — MP4, WebM, GIF + social media presets (YouTube, Instagram, Twitter)

Installation

pip install demodsl

Then install Playwright browsers:

playwright install chromium

Quick Start

1. Generate a template:

demodsl init

2. Edit demo.yaml:

metadata:
  title: "My Product Demo"

scenarios:
  - name: "Main Demo"
    url: "https://myapp.com"
    steps:
      - action: "navigate"
        url: "https://myapp.com"
        narration: "Welcome to our product!"
        effects:
          - type: "spotlight"
            duration: 2.0

pipeline:
  - generate_narration: {}
  - edit_video: {}
  - mix_audio: {}
  - optimize:
      format: "mp4"

3. Run:

demodsl run demo.yaml

4. Validate without executing:

demodsl validate demo.yaml

CLI Commands

Command	Description
demodsl run <config>	Execute the full pipeline
demodsl validate <config>	Validate config without executing
demodsl init	Generate a minimal template
demodsl init -o demo.json	Generate a JSON template

Options

• --output-dir, -o — Output directory (default: output/)
• --dry-run — Log all steps without executing
• --skip-voice — Skip TTS generation (dev mode)
• --verbose, -v — Debug logging

Architecture

DemoDSL uses a modular architecture with 5 design patterns:

Component	Pattern	Purpose
Providers	Abstract Factory	Voice, Browser, Render provider instantiation
Browser Actions	Command	Navigate, Click, Type, Scroll, WaitFor, Screenshot
Pipeline	Chain of Responsibility	11 stages with critical/optional error handling
Visual Effects	Registry + Strategy	63 effects in 2 registries (browser JS + post-processing)
Video Composition	Builder	Progressive intro → segments → watermark → outro assembly

Pipeline Stages

Stage	Critical	Description
restore_audio	Optional	Denoise (afftdn) + normalize (loudnorm) audio via ffmpeg
restore_video	Optional	Stabilize (vidstab) + sharpen (unsharp) video via ffmpeg
apply_effects	Optional	Post-processing visual effects (ordering stage)
generate_narration	Critical	TTS generation + video sync (ordering stage)
render_device_mockup	Optional	Device frame overlay via ffmpeg composite
edit_video	Critical	Intro, outro, transitions, watermark (ordering stage)
mix_audio	Critical	Voice + background music ducking
optimize	Critical	Final encoding with CRF or target bitrate
composite_avatar	Optional	Avatar overlay compositing (ordering stage)
burn_subtitles	Optional	Subtitle rendering (ordering stage)
deploy	Optional	Cloud deployment (ordering stage)

Environment Variables

Variable	Description
ELEVENLABS_API_KEY	ElevenLabs TTS API key
OPENAI_API_KEY	OpenAI API key (tts-1-hd)
GOOGLE_APPLICATION_CREDENTIALS	Path to Google Cloud service account JSON
AZURE_SPEECH_KEY	Azure Cognitive Services Speech key
AZURE_SPEECH_REGION	Azure region (default: eastus)
AWS_ACCESS_KEY_ID	AWS access key for Polly
AWS_SECRET_ACCESS_KEY	AWS secret key for Polly
AWS_DEFAULT_REGION	AWS region (default: us-east-1)
COSYVOICE_API_URL	CosyVoice API server URL (default: http://localhost:50000)
COQUI_MODEL	Coqui TTS model name (default: xtts_v2)
COQUI_LANGUAGE	Language code for Coqui TTS (default: en)
PIPER_BIN	Path to piper binary (default: piper)
PIPER_MODEL	Path to Piper .onnx voice model (required for piper engine)
LOCAL_TTS_URL	OpenAI-compatible local TTS server URL (default: http://localhost:8000)
LOCAL_TTS_API_KEY	API key for local TTS server (default: not-needed)
LOCAL_TTS_MODEL	Model name for local TTS server (default: tts-1)
ESPEAK_BIN	Path to eSpeak-NG binary (default: espeak-ng)

Without the required credentials, DemoDSL falls back to a silent dummy provider for development.

Vintage / debug providers: espeak and gtts need no API key — ideal pour le prototypage rapide. espeak donne un son robotique rétro, gtts utilise Google Translate (nécessite internet + pip install gtts).

License

MIT — see LICENSE.

Contributing

See CONTRIBUTING.md for development setup, testing, and contribution guidelines. 🇫🇷 Version française