Transcribing Youtube

Transcribing YouTube

Download audio from YouTube videos using yt-dlp, transcribe with OpenAI Whisper API, and summarize the content. Transcriptions and summaries are cached in a transcriptions/ folder to avoid redundant API calls.

Reference Files

Prerequisites

OPENAI_API_KEY, yt-dlp, ffmpeg. Phase 0 checks all three and references/installation.md covers install steps if anything is missing.

All scripts/ paths are relative to the skill directory — resolve to absolute paths before running.

Workflow Checklist

- [ ] Phase 0: Verify prerequisites
- [ ] Phase 1: Check cache for existing transcription
- [ ] Phase 2: Download audio
- [ ] Phase 3: Transcribe audio
- [ ] Phase 4: Summarize transcription
- [ ] Phase 5: Save and report

Phase 0: Verify Prerequisites

Run these checks. If anything is MISSING, read references/installation.md and install it before proceeding.

python -c "
import os, shutil
from pathlib import Path
key = os.environ.get('OPENAI_API_KEY', '')
if not key:
    env = Path('.env')
    if env.exists():
        for line in env.read_text().splitlines():
            if line.strip().startswith('OPENAI_API_KEY'):
                key = line.partition('=')[2].strip().strip('\"').strip(\"'\")
print('OPENAI_API_KEY:', 'OK' if key else 'MISSING')
print('yt-dlp:', 'OK' if shutil.which('yt-dlp') else 'MISSING')
print('ffmpeg:', 'OK' if shutil.which('ffmpeg') else 'MISSING')
"

Then ensure dependencies and output directory are ready:

pip install -r <skill-dir>/scripts/requirements.txt
mkdir -p transcriptions

Phase 1: Check Cache

Before downloading anything, check if this video has already been transcribed.

The download script extracts the video ID from the URL. Check for existing files:

ls transcriptions/<VIDEO_ID>_transcript.txt 2>/dev/null && echo "CACHED" || echo "NEW"

Extract the video ID from common URL formats:

• https://www.youtube.com/watch?v=VIDEO_ID — the v parameter
• https://youtu.be/VIDEO_ID — the path segment
• https://www.youtube.com/shorts/VIDEO_ID — the path after shorts/

If cached:

• Read the existing transcript from transcriptions/<VIDEO_ID>_transcript.txt
• Read the existing summary from transcriptions/<VIDEO_ID>_summary.txt (if it exists)
• Skip to Phase 4 if only the transcript exists (to regenerate summary), or Phase 5 if both exist
• Ask the user if they want to re-transcribe (e.g., if the previous result was poor)

Phase 2: Download Audio

Download audio only (no video) to minimize bandwidth and storage.

python scripts/download_audio.py --url "YOUTUBE_URL" --output-dir transcriptions

The script:

• Downloads the best available audio stream
• Converts to mp3 (Whisper accepts it and it's ~10x smaller than WAV)
• Splits files larger than 25MB into chunks (Whisper API limit)
• Outputs metadata: title, duration, video ID, file path(s)
• Names files as <VIDEO_ID>.mp3 (or <VIDEO_ID>_chunk_001.mp3 etc. if split)

Output format:

VIDEO_ID: dQw4w9WgXcQ
TITLE: Rick Astley - Never Gonna Give You Up
DURATION: 213
FILES: transcriptions/dQw4w9WgXcQ.mp3
STATUS: OK

If the video is longer than 3 hours, warn the user — transcription will be expensive and slow. Ask for confirmation before proceeding.

Phase 3: Transcribe Audio

Transcribe the downloaded audio using OpenAI's Whisper API.

python scripts/transcribe_audio.py --input transcriptions/<VIDEO_ID>.mp3 --output transcriptions/<VIDEO_ID>_transcript.txt

The script:

• Sends audio to OpenAI Whisper API (whisper-1 model)
• Handles chunked files automatically (concatenates results)
• Saves raw transcript text to the output file
• Includes timestamps if --timestamps flag is passed

For chunked audio (files that were split in Phase 2):

python scripts/transcribe_audio.py --input-dir transcriptions --video-id <VIDEO_ID> --output transcriptions/<VIDEO_ID>_transcript.txt

This mode auto-discovers all <VIDEO_ID>_chunk_*.mp3 files and transcribes them in order.

Output:

WORDS: 3847
DURATION_SECONDS: 213
OUTPUT: transcriptions/dQw4w9WgXcQ_transcript.txt
STATUS: OK

After transcription completes, clean up audio files to save disk space:

rm transcriptions/<VIDEO_ID>.mp3 transcriptions/<VIDEO_ID>_chunk_*.mp3 2>/dev/null

Phase 4: Summarize Transcription

Read the transcript file and produce a summary. This is done by you (the agent), not a script.

Audience: Write for a smart, knowledgeable reader. Don't pad with filler or restate the obvious. Focus on genuinely valuable insights, novel arguments, and actionable information. Omit trivial details, pleasantries, sponsor reads, advertisements, and anything a thoughtful person could infer from context. If the video references specific tools, websites, repos, or resources that viewers would find useful, mention them. For tutorials and how-to content, preserve specific values, thresholds, and step sequences — these are the primary value.

1. Read transcriptions/<VIDEO_ID>_transcript.txt
2. Produce a summary that includes:
   • Title of the video
   • Key points — bulleted list of the most substantive ideas, arguments, or takeaways. Scale with content length: a 10-minute video might warrant 3-5 bullets, a 2-hour podcast might need 15-20. Each bullet should convey real information, not vague topic labels. Prefer "X works because Y" over "Discusses X"
   • Detailed summary — length should scale with the content. A short video gets a paragraph or two; a long podcast gets as many paragraphs as needed to do justice to the material. Lead with the core thesis or most important insight. Prioritize novel or non-obvious information over background context the reader likely already knows
   • Notable quotes — direct quotes that are especially insightful, surprising, or well-stated. Include as many as are genuinely worth preserving — could be 1 for a short video, could be 10+ for a rich long-form conversation. Skip generic motivational filler
   • Metadata — duration, word count, date transcribed
3. Save to transcriptions/<VIDEO_ID>_summary.txt

Summary format:

# Video Summary: <TITLE>

**Source:** <YOUTUBE_URL>
**Duration:** <DURATION>
**Transcribed:** <DATE>
**Words:** <WORD_COUNT>

## Key Points

- Point 1
- Point 2
- ...

## Summary

<paragraphs scaled to content length>

## Notable Quotes

> "Quote 1"

> "Quote 2"

Phase 5: Save and Report

1. Confirm all files are saved:
   • transcriptions/<VIDEO_ID>_transcript.txt — full transcript
   • transcriptions/<VIDEO_ID>_summary.txt — summary
2. Clean up any remaining temporary audio files
3. Report to the user:
   • Video title and duration
   • Key points from the summary
   • File paths for transcript and summary
   • Note that cached transcriptions will be reused for this video ID

Anti-Patterns

Dependency Note

This skill requires yt-dlp, openai, and ffmpeg. Phase 0 checks availability; references/installation.md handles the rest. The only manual step for the user is providing OPENAI_API_KEY.