youtube-transcript（YouTube 成绩单）

YouTube Transcript Downloader

Extract transcripts from YouTube videos using yt-dlp. Supports manual subtitles, auto-generated captions, and Whisper transcription as a last resort.

Prerequisites

This skill requires UV for dependency management. Run from the tapestry-skills project root.

Workflow

URL → Validate → Check yt-dlp → List Subtitles → Download → Convert to Text → Save

Priority order:

1. Manual subtitles (highest quality)
2. Auto-generated captions (usually available)
3. Whisper transcription (requires user consent)

Security Requirements

All security utilities are available via UV from the project root.

URL Validation

# Validate YouTube URL (must also be a valid YouTube domain)
if [[ ! "$URL" =~ ^https?://(www\.)?(youtube\.com|youtu\.be)/ ]]; then
    echo "Error: Not a valid YouTube URL"
    exit 1
fi

# Run general security validation (SSRF protection, etc.)
uv run tapestry-validate-url "$URL" || exit 1

Filename Sanitization

# Use tapestry sanitization utility
SAFE_TITLE=$(uv run tapestry-sanitize-filename "$VIDEO_TITLE")

Step 1: Check yt-dlp Installation

yt-dlp is included in the project dependencies. Use via UV:

# yt-dlp is available through uv run
uv run yt-dlp --version

Step 2: Check Available Subtitles

Always check what's available first:

uv run yt-dlp --list-subs "$URL"

Look for:

• Available subtitles (manual, higher quality)
• Available automatic captions (auto-generated)

Step 3: Download Subtitles

Try Manual First

TEMP_DIR=$(mktemp -d)
trap "rm -rf '$TEMP_DIR'" EXIT

if uv run yt-dlp --write-sub --skip-download --sub-langs en -o "$TEMP_DIR/transcript" "$URL" 2>/dev/null; then
    echo "Downloaded manual subtitles"
else
    # Fall back to auto-generated
    uv run yt-dlp --write-auto-sub --skip-download --sub-langs en -o "$TEMP_DIR/transcript" "$URL"
    echo "Downloaded auto-generated captions"
fi

Step 4: Convert VTT to Clean Text

Use the tapestry VTT converter which handles deduplication automatically:

VIDEO_TITLE=$(uv run yt-dlp --print "%(title)s" "$URL" 2>/dev/null)
SAFE_TITLE=$(uv run tapestry-sanitize-filename "$VIDEO_TITLE")

VTT_FILE=$(find "$TEMP_DIR" -name "*.vtt" | head -n 1)

# Convert VTT to clean text (handles deduplication, HTML tags, entities)
uv run tapestry-vtt-to-text "$VTT_FILE" --output "${SAFE_TITLE}.txt"

echo "Saved: ${SAFE_TITLE}.txt"

Whisper Transcription (Last Resort)

Only offer when no subtitles are available. Requires explicit user consent.

Check File Size First

DURATION=$(uv run yt-dlp --print "%(duration)s" "$URL" 2>/dev/null)
TITLE=$(uv run yt-dlp --print "%(title)s" "$URL" 2>/dev/null)

echo "No subtitles available for: $TITLE"
echo "Duration: $((DURATION / 60)) minutes"
echo ""
echo "Download audio and transcribe with Whisper? (requires ~1-3GB for model)"
echo "Type 'yes' to proceed:"

Wait for explicit "yes" before proceeding.

Download and Transcribe

TEMP_DIR=$(mktemp -d)
trap "rm -rf '$TEMP_DIR'" EXIT

# Download audio only
uv run yt-dlp -x --audio-format mp3 -o "$TEMP_DIR/audio.%(ext)s" "$URL"

# Transcribe with Whisper (installs on first use)
uv run --with openai-whisper whisper "$TEMP_DIR/audio.mp3" --model base --output_format vtt --output_dir "$TEMP_DIR"

# Convert VTT to text
VTT_FILE=$(find "$TEMP_DIR" -name "*.vtt" | head -n 1)
uv run tapestry-vtt-to-text "$VTT_FILE" --output "${SAFE_TITLE}.txt"

Complete Workflow Script

#!/bin/bash
set -e

URL="$1"

# Validate YouTube URL
if [[ ! "$URL" =~ ^https?://(www\.)?(youtube\.com|youtu\.be)/ ]]; then
    echo "Error: Not a valid YouTube URL"
    exit 1
fi

# Run security validation
uv run tapestry-validate-url "$URL" || exit 1

# Get video info
VIDEO_TITLE=$(uv run yt-dlp --print "%(title)s" "$URL" 2>/dev/null)
SAFE_TITLE=$(uv run tapestry-sanitize-filename "$VIDEO_TITLE")

echo "Video: $VIDEO_TITLE"
echo ""

# Create temp directory
TEMP_DIR=$(mktemp -d)
trap "rm -rf '$TEMP_DIR'" EXIT

# Try to download subtitles
echo "Checking for subtitles..."
if uv run yt-dlp --write-sub --skip-download --sub-langs en -o "$TEMP_DIR/transcript" "$URL" 2>/dev/null; then
    echo "Found manual subtitles"
elif uv run yt-dlp --write-auto-sub --skip-download --sub-langs en -o "$TEMP_DIR/transcript" "$URL" 2>/dev/null; then
    echo "Found auto-generated captions"
else
    echo "No subtitles available"
    # Offer Whisper option here (with user consent)
    exit 1
fi

# Find VTT file
VTT_FILE=$(find "$TEMP_DIR" -name "*.vtt" | head -n 1)

if [ -z "$VTT_FILE" ]; then
    echo "Error: No VTT file found"
    exit 1
fi

# Convert to clean text
uv run tapestry-vtt-to-text "$VTT_FILE" --output "${SAFE_TITLE}.txt"

WORD_COUNT=$(wc -w < "${SAFE_TITLE}.txt" | tr -d ' ')

echo ""
echo "Transcript saved: ${SAFE_TITLE}.txt"
echo "Words: $WORD_COUNT"

Error Handling

Dependencies

All dependencies are managed via UV and pyproject.toml:

• yt-dlp: YouTube downloads (pinned version)
• openai-whisper (optional): For videos without subtitles

Security Reference

For complete security guidelines: ../shared/references/security-guidelines.md