rain

Social Media content generation tool for Earth App

rain is the official content generation tool for Earth App. It uses the Earth App API to fetch data about activities, events, prompts, and articles, and generates images with the content formatted in a visually appealing way.

Usage

Photo Generation

bun run photo:<type>

Where <type> is one of activity, event, prompt, or article.

Video Generation

bun run video:prompt

This command generates a vertical short-form video at out/prompt.mp4.

Pipeline:

1. Fetch one random prompt from the Earth API.
2. Read the prompt aloud with Cloudflare TTS.
3. Generate an answer with Granite 4.0 H Micro using the Cloud system prompt.
4. Read the answer aloud with Cloudflare TTS.
5. Build timed captions from prompt and answer text.
6. Animate cloud variants while narration is active.
7. Render with Remotion over a random Minecraft background window.

Additional outputs:

• out/prompt.props.json: Render props passed into Remotion.
• out/prompt.manifest.json: Generation metadata (durations, assets, text).
• src/assets/generated/prompt-*/: Generated narration audio files.

Video Notes

• Target format: 1080x1920 at 30fps.
• Timing flow: prompt narration -> short pause -> answer narration.
• Duration policy:
  • Hard maximum: 90s.
  • Hard minimum: 30s.
  • Preferred range: 60s+, with attempts centered around 80-85s.
• Captions: phrase-level closed captions tuned for spoken pacing.
• Background: random 75-90 second window sampled from src/assets/minecraft.mp4.
• Watermark: persistent Earth App logo at bottom-right.

Implementation approach (research-aligned):

• Use OffthreadVideo for stable frame-accurate background extraction.
• Use dynamic composition duration (calculateMetadata) so renders end with narration.
• Keep generation side effects out of the composition by precomputing all timing data in Bun.
• Use deterministic render props (prompt.props.json) for reproducible output/debugging.

Contributing

Contributions are welcome! Please open an issue or submit a pull request with your changes.

Licensed under the Apache License, Version 2.0. See LICENSE for more information.