flyenv-demo-video-post-production

name	flyenv-demo-video-post-production
description	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.

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.