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flyenv-demo-video-post-production

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Use when editing recorded FlyEnv screen demos into publishable videos, especially when a raw capture needs continuity-first speed ramping, a clean end cut, burned English subtitles, AI voiceover, thumbnail art, and YouTube or Bilibili upload assets.

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How to use this skill

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Source SKILL.md: https://github.com/xpf0000/FlyEnv/blob/HEAD/.codex/skills/flyenv-demo-video-post-production/SKILL.md

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Copying this prompt does not install or run the skill. Review third-party files before use. Codex skill guide

FlyEnv Demo Video Post Production

Overview

Turn a raw FlyEnv screen recording into a publishable demo package without rebuilding the story from scratch. Favor continuity, speed changes, and targeted trims over aggressive recuts.

Workflow

  1. Inspect the source video first.
    • Run ffprobe for duration, resolution, frame rate, codec, and audio presence.
    • If there is no audio, write step captions and narration from the workflow itself. Do not pretend to transcribe speech.
  2. Review frames before editing.
    • Sample the opening, several middle checkpoints, the browser walkthrough, and the final 30 to 60 seconds.
    • Find the last good product frame before any blank transition, unrelated app, or mistake. End the cut there.
  3. Create a task workspace under docs/task/<slug>/.
    • Keep the source untouched.
    • Save the render script, subtitles, voiceover, verification frames, thumbnail, and upload notes in the same folder.
  4. Build a task-local render script.
    • Structure it as: base edit -> subtitles -> title card and subtitle burn-in -> voiceover mix -> final mux -> upload assets.
    • Reuse /Users/x/.codex/skills/demo-video-pipeline/scripts/compose_demo_video.py for intro and subtitle overlays.
  5. Edit for continuity first.
    • Keep the opening and browser walkthrough at 1.0x.
    • Use 1.25x to 2.1x for long terminal or waiting sections.
    • Hard-cut only obvious dead air or a broken tail.
  6. Prefer neural English TTS.
    • First choices: en-US-BrianNeural, en-US-AndrewNeural, en-US-EmmaNeural, en-US-AvaNeural.
    • Start around --rate=-6% and adjust only if the read feels rushed.
    • If pip is blocked by PEP 668, create a task-local venv under docs/task/<slug>/.venv.
    • Use macOS say only as a fallback.
  7. Keep narration short and spoken.
    • Use direct sentences that describe what is happening now.
    • Remove abstract filler and “AI summary” phrasing.
  8. Separate video rebuilds from audio rebuilds.
    • If the pacing and cut are already correct, regenerate only the narration and remux the final MP4.
    • Do not re-encode the full video just to change the voice.
  9. Package the publishing assets.
    • Use a real product frame for the thumbnail.
    • Keep thumbnail copy short and large.
    • Write a Markdown upload package with title, description, chapters, tags, and file list.

Project Defaults

  • Export 1920x1080, 30fps, H.264 video, AAC audio, +faststart.
  • Keep source recordings in place and write outputs into docs/task/<slug>/.
  • Name artifacts consistently:
    • *_base_edited_1080p.mp4
    • *_en_subtitled.mp4
    • *_en_voiceover.wav
    • *_en_final.mp4
    • *_en_subtitles.srt
    • *_youtube_thumbnail.png
    • youtube_upload_package.md
  • Use ffmpeg, ffprobe, and magick as the default toolchain.

What Worked For FlyEnv

  • Preserve the full workflow and compress mainly with speed ramps.
  • Downscale 4K screen recordings to a 1080p publishable master.
  • Keep terminal-heavy steps faster and browser interaction slower.
  • End on the working product page and cut before any unrelated screen.
  • Switch from say to Edge neural TTS when the voice sounds too synthetic.
  • Add an audio-only rebuild path so voice improvements stay cheap.

Avoid

  • Aggressive cuts that make the demo hard to follow.
  • Leaving a broken tail after the final successful browser view.
  • Re-encoding the whole video when only narration changed.
  • Overlong thumbnail text blocks.
  • Creating extra planning or review docs for straightforward post-production passes.

References

  • Read references/retrospective.md for the concrete lessons from the July 2026 FlyEnv demo edit.
  • If a task-specific render script already exists in the task folder, patch it instead of rewriting it.