Self-Hosted n8n Workflow: Gemini/Claude Shorts w/ Edge TTS & FFmpeg

Turn an n8n topic into a ready-to-post vertical short—self-hosted

This self-hosted n8n workflow takes a topic from an n8n Form Trigger, generates a multi-scene short using Google Gemini or Anthropic Claude, creates synchronized voiceover with Edge TTS, downloads scene visuals from Pollinations, and renders a final vertical MP4 using FFmpeg (with karaoke-style burned captions).

What this workflow does

• Collect inputs: Receives topic, language, scene count, and LLM choice from an n8n Form Trigger.
• Voice + pacing logic: Maps the selected language to an Edge TTS voice and calculates a per-scene word limit to keep the total video under 60 seconds.
• Generate the script: Produces a JSON script containing voiceover text plus English image prompts per scene using either Google Gemini or Anthropic Claude.
• Scene-by-scene rendering:
  • Splits the script into scenes and generates an MP3 voiceover per scene with Edge TTS.
  • Estimates caption timing word-by-word using ffprobe/FFmpeg silence detection.
  • Downloads a 1080×1920 image per scene from Pollinations based on the scene prompt.
  • Renders each scene locally with FFmpeg: applies a slow zoom effect and burns karaoke-style ASS subtitles synced to the audio.
• Finalize output: Concatenates all scene segments into a single vertical MP4, normalizes audio loudness, and returns the final video as the workflow output.

Use cases

• Generate TikTok/Shorts-style vertical videos from form submissions without third-party video tools.
• Automate “script → voice → captions → render” for SaaS marketing, creator ops, or rapid testing of content ideas.
• Keep data and rendering self-hosted while switching between Gemini and Claude.

Technical details

• LLMs: Google Gemini or Anthropic Claude
• Voice: Microsoft Edge TTS
• Images: Pollinations (1080×1920 per scene)
• Video & captions: FFmpeg + ffprobe (libass for burned ASS subtitles)
• n8n nodes referenced: code, merge, switch, split out, aggregate, sticky note
• Self-host setup: Start n8n with NODES_EXCLUDE="[]" and N8N_RESTRICT_FILE_ACCESS_TO="/tmp" (macOS: "/tmp;/private/tmp") and enable local Execute Command + file access.