Video Cleaning

Video Cleaning Skill

Automated video transcription and editing workflow that removes pauses and filler words from Korean videos using OpenAI Whisper API and MoviePy for frame-accurate cuts.

When to Use This Skill

Use this skill when you need to:

• Clean up recorded presentations or talks
• Remove awkward pauses and "uh/um" sounds from videos
• Reduce video length by removing dead air
• Create polished videos from raw recordings
• Process Korean language videos with natural speech patterns

Perfect for: Presentation recordings, lecture videos, podcast recordings, interview footage, or any speaking video that needs cleaning.

Example Results

See the before/after comparison:

• Before: https://youtu.be/2jfRBlQ4veI (1:13 original)
• After: https://youtu.be/ZTsFZs9w65M (0:45 edited, 39% reduction)

Requirements

System Requirements

• FFmpeg: Video processing tool (must be installed)
  • macOS: brew install ffmpeg
  • Linux: sudo apt install ffmpeg
  • Windows: Download from ffmpeg.org

Python Requirements

• OpenAI Python SDK: pip install openai
• MoviePy: pip install moviepy (video editing with frame accuracy)
• OpenAI API Key: Set environment variable OPENAI_API_KEY
  • Get your API key from platform.openai.com
  • Cost: ~$0.15 per 25-minute video (Whisper transcription)

Python Version

• Python 3.7 or higher

How It Works

This skill uses a two-step workflow:

Step 1: Transcription (transcribe_video.py)

1. Extracts audio from video using FFmpeg
2. Sends audio to OpenAI Whisper API for transcription
3. Receives word-level timestamps (precise timing for each word)
4. Generates three output files:
   • {video_name} - transcript.json (complete API response)
   • {video_name} - transcript.md (formatted markdown)
   • {video_name} - word_timings.txt (simple text reference)

Step 2: Video Editing (edit_video_remove_pauses.py)

1. Loads word-level transcript from Step 1
2. Identifies long pauses between words (> 1.0 seconds by default)
3. Identifies Korean filler words (어, 음, 아, 이, 오, 저)
4. Calculates which video segments to keep
5. Uses MoviePy for frame-accurate cutting and reassembly
6. Generates edited video and detailed report

Conservative Editing Philosophy

This skill uses conservative editing to ensure safe, predictable results:

What Gets Removed

• ✅ Long pauses (>1.0 seconds of silence between words)
• ✅ Clear filler words: 어, 음, 아, 이, 오, 저 (Korean equivalents of "uh", "um", "ah", etc.)

What Gets Kept

• ✅ Context-dependent words: 이제, 뭐, 그, 좀, 네, 약간
  • These words can be legitimate in Korean speech
  • Removing them risks cutting meaningful content
• ✅ Short pauses (< 1.0 seconds)
  • Natural breathing and thinking pauses
  • Important for speech rhythm

Expected Results

• Time saved: 5-10% typically (1-2 minutes per 25-minute video)
• Video segments: 50-100 cuts (manageable, smooth transitions)
• Safety: Very low risk of removing important content
• Quality: Natural-sounding edited video

Usage Guide

Basic Workflow

# Step 1: Transcribe your video
python transcribe_video.py "my_presentation.mp4"

# Step 2: Preview what will be removed
python edit_video_remove_pauses.py "my_presentation.mp4" --preview

# Step 3: Create edited video
python edit_video_remove_pauses.py "my_presentation.mp4"

Step 1: Transcription Options

# Basic transcription (Korean, default)
python transcribe_video.py "video.mp4"

# Custom output directory
python transcribe_video.py "video.mp4" --output-dir "transcripts"

# Keep extracted audio file
python transcribe_video.py "video.mp4" --keep-audio

# English transcription
python transcribe_video.py "video_en.mp4" --language "en"

Transcription outputs (auto-generated in same directory as video):

• video - transcript.json (464 KB for 25-min video, ~2,800 words)
• video - transcript.md (formatted with timestamps)
• video - word_timings.txt (simple reference)

Step 2: Video Editing Options

# Preview mode (see what will be removed)
python edit_video_remove_pauses.py "video.mp4" --preview

# Basic editing (default settings)
python edit_video_remove_pauses.py "video.mp4"

# Custom pause threshold (remove pauses > 0.8 seconds)
python edit_video_remove_pauses.py "video.mp4" --pause-threshold 0.8

# Custom output path
python edit_video_remove_pauses.py "video.mp4" --output "cleaned_video.mp4"

# Adjust padding around cuts (default: 0.1 seconds)
python edit_video_remove_pauses.py "video.mp4" --padding 0.15

# Specify transcript location (if not auto-detected)
python edit_video_remove_pauses.py "video.mp4" --transcript "path/to/transcript.json"

# Skip filler word removal (only remove pauses)
python edit_video_remove_pauses.py "video.mp4" --no-fillers

# Save pauses data for chapter remapping (used by video-full-process)
python edit_video_remove_pauses.py "video.mp4" --output-pauses "video - pauses.json"

Editing outputs:

• video - edited.mov (cleaned video)
• video - edited_edit_report.txt (detailed report)

Understanding the Edit Report

After editing, you'll receive a detailed report showing exactly what was removed:

============================================================
VIDEO EDIT REPORT (Conservative Mode)
============================================================

SUMMARY
------------------------------------------------------------
Original Duration:  00:25:21.000
Edited Duration:    00:23:16.690
Time Saved:         00:02:04.310 (8.2%)
Segments Kept:      67

PAUSES REMOVED
------------------------------------------------------------
Total Pauses:       43
Total Pause Time:   87.81 seconds

Top 10 Longest Pauses:
   1.  5.64s at 00:07:51.500
   2.  5.52s at 00:09:21.020
   3.  3.54s at 00:00:11.520
   ...

FILLER WORDS REMOVED (Clear Fillers Only)
------------------------------------------------------------
Total Fillers:      28
Breakdown:
  어     :  25 occurrences
  아     :   3 occurrences

SAMPLE EDITS (First 5)
------------------------------------------------------------
  1. Pause (3.54s) at 00:00:11.520
  2. Pause (1.50s) at 00:00:29.400
  3. Filler '어' (0.84s) at 00:05:32.140
  ...

Advanced Usage

Custom Pause Thresholds

Adjust based on your content:

# More aggressive pause removal (0.8 seconds)
python edit_video_remove_pauses.py "video.mp4" --pause-threshold 0.8

# Very conservative (only remove 2+ second pauses)
python edit_video_remove_pauses.py "video.mp4" --pause-threshold 2.0

Guidelines:

• 0.5-0.8s: Aggressive, removes more pauses but may feel rushed
• 1.0s (default): Balanced, removes awkward pauses while keeping natural rhythm
• 1.5-2.0s: Very conservative, only removes obvious dead air

Batch Processing Multiple Videos

# Process all videos in a directory
for video in *.mp4; do
    echo "Processing: $video"
    python transcribe_video.py "$video"
    python edit_video_remove_pauses.py "$video"
done

Preview Before Editing

Always preview first when working with important content:

# Step 1: Transcribe
python transcribe_video.py "important_presentation.mp4"

# Step 2: Preview edits
python edit_video_remove_pauses.py "important_presentation.mp4" --preview

# Step 3: If satisfied, execute
python edit_video_remove_pauses.py "important_presentation.mp4"

File Naming Conventions

The scripts follow consistent naming patterns:

Input:

• presentation.mp4 (your original video)

Transcription outputs:

• presentation - transcript.json (complete data)
• presentation - transcript.md (formatted markdown)
• presentation - word_timings.txt (simple reference)

Editing outputs:

• presentation - edited.mov (cleaned video)
• presentation - edited_edit_report.txt (detailed report)

Technical Details

MoviePy Processing

The editing script uses MoviePy for frame-accurate cutting:

• ✅ Precise: Cuts at exact timestamps, not keyframe boundaries
• ✅ Accurate: No ±1-2 second drift from keyframe limitations
• ✅ Quality: Re-encodes with libx264/AAC for consistent output
• ⚠️ Slower: Re-encoding takes more time than codec copy (worth it for accuracy)

Minimum Segment Duration

Segments shorter than 0.1 seconds are automatically filtered out:

• Prevents FFmpeg errors
• Avoids meaningless micro-cuts
• Ensures smooth playback

Word-Level Timestamp Precision

Whisper API provides timestamps accurate to ~0.01 seconds:

• Precise enough for clean cuts between words
• Allows surgical removal of specific words
• Enables accurate pause detection

Cut Parameters: padding & tail_buffer

두 파라미터는 컷 지점의 정확도를 조절합니다. Whisper 타임스탬프가 완벽하지 않기 때문에 버퍼가 필요합니다.

gantt
    title 원본 오디오 타임라인
    dateFormat X
    axisFormat %s

    section 원본
    단어 A          :a, 0, 2
    휴지 (침묵)      :crit, pause, 2, 5
    단어 B          :b, 5, 8

flowchart LR
    subgraph 원본["원본 오디오"]
        direction LR
        A["🗣️ 단어 A<br/>0-2초"]
        P["🔇 휴지<br/>2-5초"]
        B["🗣️ 단어 B<br/>5-8초"]
        A --> P --> B
    end

flowchart TB
    subgraph params["파라미터 작동 원리"]
        direction TB

        subgraph timeline["타임라인 (초)"]
            direction LR
            t0["0"] ~~~ t2["2"] ~~~ t5["5"] ~~~ t8["8"]
        end

        subgraph original["원본"]
            direction LR
            wordA["단어 A<br/>0~2초"]
            pause["휴지<br/>2~5초"]
            wordB["단어 B<br/>5~8초"]
            wordA --> pause --> wordB
        end

        subgraph cuts["컷 포인트"]
            direction LR
            tail["◀── tail_buffer<br/>휴지 시작점을<br/>0.15초 뒤로 연장"]
            pad["padding ──▶<br/>휴지 끝점에서<br/>0.1초 건너뜀"]
        end

        subgraph result["편집 결과"]
            direction LR
            keepA["✅ 유지: 0 ~ 2.15초<br/>(단어A + tail_buffer)"]
            remove["❌ 제거: 2.15 ~ 5.1초"]
            keepB["✅ 유지: 5.1 ~ 8초<br/>(padding 후 단어B)"]
            keepA --> remove --> keepB
        end
    end

    style pause fill:#ffcccc
    style remove fill:#ffcccc
    style keepA fill:#ccffcc
    style keepB fill:#ccffcc

파라미터 요약:

음성이 잘리는 경우:

• 단어 끝이 잘림 → --tail-buffer 증가 (예: 0.25)
• 단어 시작이 잘림 → --padding 감소 (예: 0.05)

Troubleshooting

"Transcript not found" Error

Error: Transcript not found: video - transcript.json

Solution: Run transcription first or specify transcript location:

python transcribe_video.py "video.mp4"
# OR
python edit_video_remove_pauses.py "video.mp4" --transcript "path/to/transcript.json"

"No word-level data found" Error

Solution: Transcript JSON is incomplete or corrupted. Re-run transcription:

python transcribe_video.py "video.mp4"

FFmpeg Not Found

Error: ffmpeg not found

Solution: Install FFmpeg:

• macOS: brew install ffmpeg
• Linux: sudo apt install ffmpeg
• Windows: Download from ffmpeg.org

OpenAI API Key Missing

Error: OPENAI_API_KEY environment variable not set

Solution: Set your API key:

export OPENAI_API_KEY="sk-..."  # Add to ~/.bashrc or ~/.zshrc

Edited Video Duration Mismatch

With MoviePy frame-accurate editing:

• Duration should match calculated time very closely
• If significantly different, check transcript timestamps
• Re-run transcription if timestamps seem off

Video Quality Issues

If you notice quality degradation:

• Verify original video quality is good
• MoviePy uses libx264/AAC encoding with preset=fast
• For higher quality, modify script to use preset=slow

Performance Characteristics

Transcription (Step 1)

• Speed: ~1-2 minutes for 25-minute video
• Cost: ~$0.15 per 25 minutes (OpenAI Whisper pricing)
• Output size: ~500 KB JSON for 25-minute video

Editing (Step 2)

• Speed: ~5-10 minutes for 25-minute video (re-encoding)
• CPU usage: High during encoding (uses 4 threads by default)
• Disk space: ~1.5x original video size during processing
• Output quality: High (libx264 + AAC encoding)

Expected Time Savings

Based on typical Korean presentation videos:

• Conservative mode: 5-10% reduction (1-2 minutes per 25-minute video)
• Longer pauses: Can save 10-15% if speaker has many long pauses
• Professional speakers: May save less (3-5%) due to fewer pauses

Example Workflow

Here's a complete example from start to finish:

# 1. You have a recorded presentation
ls
# presentation.mp4 (25:21 duration)

# 2. Transcribe the video
python transcribe_video.py "presentation.mp4"
# Output: Found 2,835 words
# Cost: $0.15
# Files created:
#   - presentation - transcript.json
#   - presentation - transcript.md
#   - presentation - word_timings.txt

# 3. Preview what will be removed
python edit_video_remove_pauses.py "presentation.mp4" --preview
# Found 43 pauses > 1.0s
# Found 28 filler word instances
# Video will be split into 67 segments
# Time saved: 00:02:04 (8.2%)

# 4. Looks good! Create edited video
python edit_video_remove_pauses.py "presentation.mp4"
# Cutting video segments... (3 minutes)
# Concatenating segments... (1 minute)
# ✅ Success! Edited video saved to: presentation - edited.mov

# 5. Review the results
ls
# presentation.mp4                          (original)
# presentation - edited.mov                 (cleaned, 23:17)
# presentation - edited_edit_report.txt     (detailed report)
# presentation - transcript.json
# presentation - transcript.md
# presentation - word_timings.txt

Best Practices

1. Always Preview First

python edit_video_remove_pauses.py "video.mp4" --preview

Review the report before committing to editing.

2. Keep Original Files

Never delete your original video until you've verified the edited version.

3. Test Threshold Settings

Try different --pause-threshold values on a test video to find what works best for your content.

4. Check Audio Quality

Ensure audio is clear before transcription. Whisper works best with:

• Clear speech (not too fast or mumbled)
• Minimal background noise
• Good microphone quality

5. Batch Process Wisely

For multiple videos, process one completely first to verify settings, then batch the rest.

Limitations

What This Skill Cannot Do

• ❌ Remove background noise or improve audio quality
• ❌ Fix video quality issues
• ❌ Remove visual distractions or objects
• ❌ Auto-detect and remove specific speakers
• ❌ Add subtitles or captions (use transcript for this separately)

Language Support

• ✅ Optimized for Korean: Filler word detection is Korean-specific
• ⚠️ English: Works for pauses, but filler words need adjustment
• ⚠️ Other languages: Transcription works, but filler detection needs customization

Video Format Compatibility

• ✅ Tested: MP4, MOV, AVI, MKV
• ✅ Output: MOV format (universally compatible)
• ⚠️ Codecs: Best with H.264/AAC, may have issues with exotic codecs

Cost Breakdown

OpenAI Whisper API Costs

• Pricing: $0.006 per minute of audio
• Examples:
  • 25-minute video: $0.15
  • 1-hour video: $0.36
  • 10 videos (25 min each): $1.50

Computing Costs

• Transcription: Minimal (API call only)
• Editing: Minimal (local FFmpeg processing)
• Storage: ~500 KB per 25-minute video (transcript JSON)

Total cost per video: Primarily OpenAI API fees (~$0.006/minute)

Integration with video-add-chapters

This skill can be combined with video-add-chapters for a complete video processing workflow. Use the video-full-process skill for an automated pipeline:

# Full processing with transcript reuse
python process_video.py "video.mp4" --language ko

The --output-pauses flag exports pause data in JSON format for chapter timestamp remapping:

{
  "pauses": [
    {"start": 45.2, "end": 48.5, "duration": 3.3},
    {"start": 120.1, "end": 125.8, "duration": 5.7}
  ],
  "total_pause_time": 87.5
}

This data enables accurate chapter remapping after pauses are removed.

Support & Updates

Getting Help

• Check error messages in the edit report
• Review troubleshooting section above
• Verify FFmpeg installation: ffmpeg -version
• Verify OpenAI API key: echo $OPENAI_API_KEY

Skill Location

_Settings_/Skills/video-cleaning/
├── SKILL.md                          # This documentation
├── README.md                         # Quick reference
├── transcribe_video.py               # Step 1: Transcription
└── edit_video_remove_pauses.py       # Step 2: Editing

Version History

• v2.0 (2026-01): MoviePy migration for frame accuracy
  • Replaced FFmpeg codec-copy with MoviePy re-encoding
  • Frame-accurate cuts (no keyframe limitations)
  • Extended filler words: 어, 음, 아, 이, 오, 저
  • Added --no-fillers option
  • Smart tail_buffer for word endings preservation
• v1.0 (2024): Initial conservative mode release
  • Removed aggressive and smart clustering modes
  • Focused on reliable, predictable editing
  • Korean filler word support (어, 음, 아)

Quick Reference Card

┌─────────────────────────────────────────────────────────┐
│ VIDEO CLEANING WORKFLOW - QUICK REFERENCE              │
├─────────────────────────────────────────────────────────┤
│                                                          │
│ STEP 1: TRANSCRIBE                                      │
│   python transcribe_video.py "video.mp4"                │
│   → Creates: video - transcript.json                    │
│                                                          │
│ STEP 2: PREVIEW                                         │
│   python edit_video_remove_pauses.py "video.mp4" \      │
│     --preview                                            │
│   → Shows: What will be removed                         │
│                                                          │
│ STEP 3: EDIT                                            │
│   python edit_video_remove_pauses.py "video.mp4"        │
│   → Creates: video - edited.mov                         │
│                                                          │
│ COMMON OPTIONS:                                         │
│   --pause-threshold 0.8    Remove pauses > 0.8s         │
│   --padding 0.15           Add 0.15s padding at cuts    │
│   --output "clean.mp4"     Custom output path           │
│   --no-fillers             Skip filler word removal     │
│                                                          │
│ WHAT GETS REMOVED:                                      │
│   ✓ Pauses > 1.0 seconds                                │
│   ✓ Filler words: 어, 음, 아, 이, 오, 저                │
│                                                          │
│ EXPECTED RESULTS:                                       │
│   • 5-10% time reduction                                │
│   • 50-100 video segments                               │
│   • Natural-sounding output                             │
│                                                          │
└─────────────────────────────────────────────────────────┘

Ready to clean your videos? Start with the basic workflow and adjust settings as needed. Remember: always preview first, and keep your originals safe!