Video Encoding Standards

Intermediate

Enforce consistent video encoding parameters — codec selection, CRF ranges, pixel formats, faststart flags, and profile/level settings for reliable cross-platform media output.

File Patterns

**/*.sh**/*.bash**/Makefile

This rule applies to files matching the patterns above.

Rule Content

rule-content.md

# Video Encoding Standards

## Rule
All FFmpeg video encoding commands MUST specify codec, quality method (CRF/bitrate), pixel format, and include `-movflags +faststart` for web-targeted output.

## Required Parameters for Web Video
```bash
ffmpeg -i input.mp4 \
  -c:v libx264 \          # REQUIRED: explicit codec
  -crf 23 \               # REQUIRED: quality level
  -preset medium \         # REQUIRED: speed/compression tradeoff
  -profile:v high \        # REQUIRED: compatibility profile
  -level 4.1 \            # REQUIRED: device compatibility level
  -pix_fmt yuv420p \      # REQUIRED: browser-compatible pixel format
  -c:a aac -b:a 128k \   # REQUIRED: audio codec and bitrate
  -movflags +faststart \  # REQUIRED: progressive download
  output.mp4
```

## CRF Ranges
| Codec | Excellent | Good | Acceptable | Max |
|-------|-----------|------|------------|-----|
| libx264 | 18 | 23 | 28 | 51 |
| libx265 | 20 | 28 | 32 | 51 |
| libsvtav1 | 20 | 30 | 38 | 63 |

## Good Example
```bash
ffmpeg -i raw.mov \
  -c:v libx264 -crf 22 -preset medium \
  -profile:v high -level 4.1 \
  -pix_fmt yuv420p \
  -c:a aac -b:a 128k \
  -movflags +faststart \
  web_ready.mp4
```

## Bad Example
```bash
# Missing codec, CRF, pixel format, faststart
ffmpeg -i raw.mov output.mp4
# FFmpeg uses defaults which may not be web-compatible
```

## Anti-Patterns
- Encoding without explicit codec (unpredictable output)
- Missing `-pix_fmt yuv420p` (Safari won't play yuv444p)
- Missing `-movflags +faststart` for web delivery
- CRF > 28 for H.264 (visible quality loss)
- Using `-preset veryslow` for non-archival content (wastes hours)
- Re-encoding with stream copy available (`-c copy`)

FAQ

Discussion

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# Video Encoding Standards ## Rule All FFmpeg video encoding commands MUST specify codec, quality method (CRF/bitrate), pixel format, and include `-movflags +faststart` for web-targeted output. ## Required Parameters for Web Video ```bash ffmpeg -i input.mp4 \ -c:v libx264 \ # REQUIRED: explicit codec -crf 23 \ # REQUIRED: quality level -preset medium \ # REQUIRED: speed/compression tradeoff -profile:v high \ # REQUIRED: compatibility profile -level 4.1 \ # REQUIRED: device compatibility level -pix_fmt yuv420p \ # REQUIRED: browser-compatible pixel format -c:a aac -b:a 128k \ # REQUIRED: audio codec and bitrate -movflags +faststart \ # REQUIRED: progressive download output.mp4 ``` ## CRF Ranges | Codec | Excellent | Good | Acceptable | Max | |-------|-----------|------|------------|-----| | libx264 | 18 | 23 | 28 | 51 | | libx265 | 20 | 28 | 32 | 51 | | libsvtav1 | 20 | 30 | 38 | 63 | ## Good Example ```bash ffmpeg -i raw.mov \ -c:v libx264 -crf 22 -preset medium \ -profile:v high -level 4.1 \ -pix_fmt yuv420p \ -c:a aac -b:a 128k \ -movflags +faststart \ web_ready.mp4 ``` ## Bad Example ```bash # Missing codec, CRF, pixel format, faststart ffmpeg -i raw.mov output.mp4 # FFmpeg uses defaults which may not be web-compatible ``` ## Anti-Patterns - Encoding without explicit codec (unpredictable output) - Missing `-pix_fmt yuv420p` (Safari won't play yuv444p) - Missing `-movflags +faststart` for web delivery - CRF > 28 for H.264 (visible quality loss) - Using `-preset veryslow` for non-archival content (wastes hours) - Re-encoding with stream copy available (`-c copy`)