Video Study Notes

Goal

Given one video source, build a local note project that:

1. resolves a deterministic project root before creating any directories
2. reuses existing subtitle text when available
3. falls back to local transcription only if no usable subtitle text exists
4. extracts candidate screenshots from scene changes and important timestamps
5. has the model review those candidate screenshots and keep the most informative ones
6. produces one concise, high-signal Markdown note with images placed near the relevant explanation

Linux prerequisites

This skill is intended to run on Linux machines and must use uv to manage the environment stored in the skill-local .venv.

Minimum system dependencies:

• python3
• ffmpeg
• uv

Recommended bootstrap flow from the repo root:

cd .agent/skills/video-study-notes
sudo apt install -y python3 python3-venv ffmpeg
bash scripts/bootstrap_linux.sh
.venv/bin/python scripts/check_linux_env.py

Notes:

• CPU mode is the portability baseline and should work on ordinary Linux machines.
• NVIDIA GPU acceleration is optional. If CUDA initialization fails, the transcription script falls back to CPU automatically.
• Keep the virtual environment inside this skill directory and manage it with uv.

Project root selection

Before creating any directories, resolve the folder layout first.

1. Use subskills/yt-dlp/scripts/resolve_project_root.py to sanitize names and compute the project root.
   • unless the caller overrides --output-base, the default base directory is <workspace_root>/output/, where <workspace_root> is the parent directory of the nearest .agent or .codex directory
2. If the source is a series / playlist / course, use the series title as the first-level folder and the video title as the second-level folder:
   • <workspace_root>/output/<Series Title>/<Video Title>/
   • when the metadata is a multi-entry container, pass --entry-index for the selected item or pass its title explicitly with --video-title
3. If the source is not a series, use the video title as the first-level folder:
   • <workspace_root>/output/<Video Title>/
4. Never improvise a different folder convention once the script has resolved the root.

Use human-readable names, but strip or replace path separators, control characters, and other filesystem-hostile characters.

Input routing

Route the workflow from the user's input before doing any heavy work.

1. If the user gave a URL:
   • probe metadata first
   • if the selected URL may hide the surrounding series container, also probe the canonical container URL before resolving the project root
   • resolve the project root from that metadata
   • if the metadata contains multiple entries, choose the intended item before resolving the root
   • probe subtitle availability before deciding whether transcription is needed
2. If the user gave a local video file:
   • skip all download steps
   • resolve the project root from the local file path and any reliable series title the user provided
   • check for local sidecar subtitle files with subskills/media-transcribe/scripts/find_local_subtitles.py
3. Use the best available subtitle or transcript source in this order:
   • downloaded regular subtitle tracks
   • local sidecar subtitle files for a local video
   • local SRT produced by media-transcribe
   • danmaku only as last-resort context, never as a substitute for spoken-content transcription

Default project layout

After choosing the project root, keep everything for that video inside it.

If this is a standalone video:

• <workspace_root>/output/<Video Title>/video/
• <workspace_root>/output/<Video Title>/audio/
• <workspace_root>/output/<Video Title>/subtitles/
• <workspace_root>/output/<Video Title>/transcripts/
• <workspace_root>/output/<Video Title>/keyframes/
• <workspace_root>/output/<Video Title>/notes.md
• <workspace_root>/output/<Video Title>/keyframe_timestamps.txt

If this video belongs to a series, add one more level first:

• <workspace_root>/output/<Series Title>/<Video Title>/video/
• <workspace_root>/output/<Series Title>/<Video Title>/audio/
• <workspace_root>/output/<Series Title>/<Video Title>/subtitles/
• <workspace_root>/output/<Series Title>/<Video Title>/transcripts/
• <workspace_root>/output/<Series Title>/<Video Title>/keyframes/
• <workspace_root>/output/<Series Title>/<Video Title>/notes.md
• <workspace_root>/output/<Series Title>/<Video Title>/keyframe_timestamps.txt

The user explicitly wants all screenshots under the chosen project root's keyframes/ directory.

Workflow

1. Determine whether the input is a URL or a local video path.
2. If the input is a URL, dump metadata first and resolve the project root with subskills/yt-dlp/scripts/resolve_project_root.py before any download step.
3. If the selected URL points at one entry inside a larger series and hides the container metadata, probe the canonical series/container URL first, then select the intended item with --entry-index or explicit titles.
4. If that metadata is a multi-entry container, choose the specific item first and pass --entry-index or --video-title to resolve_project_root.py.
5. If the input is a local video path, resolve the project root with subskills/yt-dlp/scripts/resolve_project_root.py from the local file path and skip download steps entirely.
6. Create video/, audio/, subtitles/, transcripts/, and keyframes/ inside that project root.
7. For a URL source, probe the subtitle situation with the yt-dlp subskill. If the site may require login, make subtitle probes with the same cookies strategy used for subtitle downloads.
8. For a local video source, probe sibling subtitle files and common subtitle subdirectories with subskills/media-transcribe/scripts/find_local_subtitles.py.
9. Only download the video when the input is a URL, and save it to <project_root>/video/.
10. If the URL source has usable subtitle tracks, download them to <project_root>/subtitles/ and use them as the primary text source.
11. If the local video source has usable sidecar subtitle files, copy or reuse them under <project_root>/subtitles/ and use them as the primary text source.
12. Only if no usable subtitle text source exists, create or reuse audio under <project_root>/audio/ and invoke the media-transcribe subskill to create an SRT transcript under <project_root>/transcripts/.
    • if the input is a local or downloaded video file, use scripts/prepare_audio.py so the audio artifact lives deterministically under <project_root>/audio/
    • if the input is already a local audio file, copy it into <project_root>/audio/ or point prepare_audio.py at it so the note project stays self-contained
13. Extract scene-change keyframes with scripts/extract_keyframes.py into <project_root>/keyframes/.
14. Read the chosen subtitle/transcript and identify important timestamps such as:

Keyframe extraction

The helper script only extracts candidate frames. It does not score, rank, deduplicate, or select them for you. It does clear stale scene-*.jpg and cue-*.jpg candidates before rewriting those sets, so reruns stay deterministic.

Use the bundled helper script:

cd .agent/skills/video-study-notes
.venv/bin/python scripts/extract_keyframes.py --video "<project_root>/video/example.mp4" --output-dir "<project_root>/keyframes"

After you decide which subtitle/transcript timestamps are important, place them in a text file such as <project_root>/keyframe_timestamps.txt:

12.5
85.0

• section transitions
• slides with definitions or equations
• code or demo milestones
• diagrams, tables, and architecture overviews