video-editor

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---
name: video-editor
description: Expert guidance for video editing with ffmpeg, encoding best practices, and quality optimization. Use when working with video files, transcoding, remuxing, encoding settings, color spaces, or troubleshooting video quality issues.
---

# Video Editor - FFmpeg & Encoding Expert

Expert guidance for video editing, encoding, and processing with ffmpeg. This skill covers container formats, codecs, encoding best practices, and quality optimization for video production workflows.

## When to Use This Skill

Use this skill when:
- Encoding or transcoding video files
- Converting between container formats (MKV, MP4, etc.)
- Optimizing encoding settings for quality or file size
- Troubleshooting video quality issues
- Working with color spaces and color matrices
- Hardsubbing or softsubbing videos
- Preparing videos for specific platforms or devices
- Understanding why a video looks wrong after processing

## Core Concepts

### Container vs. Codec

**This distinction is critical.** File extensions like `.mkv` or `.mp4` are **container formats** that package already-compressed streams. The actual compression happens through **codecs** like H.264, H.265, VP9, or AV1.

| Concept | What It Is | Examples |
|---------|------------|----------|
| Container | Wrapper that holds video/audio/subtitle streams | MKV, MP4, AVI, MOV, WebM |
| Codec | Algorithm that compresses/decompresses video | H.264, H.265/HEVC, VP9, AV1 |
| Encoder | Software that implements a codec | x264, x265, libvpx, NVENC |

### Remuxing vs. Reencoding

| Operation | What It Does | Quality Impact | Speed |
|-----------|--------------|----------------|-------|
| **Remuxing** | Moves streams between containers without re-compression | None (lossless) | Very fast |
| **Reencoding** | Decodes and re-encodes video with new settings | Always loses quality | Slow |

**Rule of thumb:** If you only need to change the container format, remux. Only reencode when absolutely necessary.

## Quality Principles

### What "Quality" Actually Means

Video quality measures **how closely the output resembles the source**. Every processing step moves the video further from the original. There is no way to add quality - only preserve or lose it.

### Common Misconceptions

| Myth | Reality |
|------|---------|
| Higher resolution = better quality | Resolution is just dimensions; a 720p video can look better than a 4K one |
| Higher bitrate = better quality | Encoder efficiency matters more; same quality at different sizes is possible |
| H.265 is always 50% smaller | Depends on encoder settings; poorly-configured H.265 can be worse than H.264 |
| Hardware encoding is fine for quality | Hardware encoders (NVENC, QuickSync) sacrifice quality for speed |
| AI upscaling improves quality | Upscaling adds artificial detail that wasn't in the source |

### The Encoding Quality Hierarchy

From most to least important:
1. **Encoder settings** (CRF, preset, tuning)
2. **Encoder choice** (x264/x265 vs. hardware encoders)
3. **Codec** (H.265 vs. H.264 vs. VP9)

## Quick Reference: FFmpeg Commands

### Remux (Change Container, No Quality Loss)

```bash
# MKV to MP4 (preserves all streams)
ffmpeg -i input.mkv -c copy output.mp4

# MP4 to MKV
ffmpeg -i input.mp4 -c copy output.mkv
```

### Basic Encoding

```bash
# Encode with x264, copy audio
ffmpeg -i input.mkv -c:a copy -c:v libx264 -preset slower -crf 20 output.mkv

# Encode with x265
ffmpeg -i input.mkv -c:a copy -c:v libx265 -preset slower -crf 22 output.mkv
```

### Quality-Focused Encoding

```bash
# High-quality x264 for animation
ffmpeg -i input.mkv -c:a copy -c:v libx264 -preset slower -crf 18 \
  -x264-params bframes=8 output.mkv

# High-quality x265
ffmpeg -i input.mkv -c:a copy -c:v libx265 -preset slower -crf 20 \
  -x265-params bframes=8 output.mkv
```

## Encoding Settings Deep Dive

### CRF (Constant Rate Factor)

CRF controls quality vs. file size tradeoff. **Lower = higher quality, larger file.**

| CRF Rang