convert-to-avif

name	convert-to-avif
description	Use when the user wants AVIF output — modern web format with ~30% better compression than WebP at the same visual quality, and ~50% better than JPEG. Wraps `avifenc`. Companion to `convert-to-webp`. Best target for new web work; check browser support if delivering to ancient clients.

Convert to AVIF

Encode JPEG/PNG/TIFF to AVIF. AVIF beats WebP on compression ratio and supports 10/12-bit, HDR, and lossless modes. Browser support is universal as of 2024 (Chrome 85+, Firefox 113+, Safari 16.4+).

When to use

• Web-prep where modern browser support is fine.
• Archival of high-bit-depth photos (10/12-bit AVIF preserves more than JPEG).
• Pre-step inside web-ready orchestrator.

Do not use this skill when:

• Output must work in Safari <16.4 / IE / very old Android browsers — fall back to WebP or JPEG.
• Source is already AVIF — no point re-encoding.
• You need lossless re-encoding of a JPEG that should remain bit-exact-decodable — that's convert-to-jxl's unique trick, not AVIF's.

Inputs

1. Input — file or directory. Required.
2. Quality — avifenc -q N (0–100). Default 60 (visually equivalent to JPEG q82, much smaller). 80 for archival; 45 for aggressive.
3. Speed/effort — avifenc -s <0..10>. Default 6 (balanced). 0 is best compression but very slow; 10 is fast but bigger files.
4. Lossless — --lossless. Enables lossless mode (ignores quality). For exact archival of PNG.
5. Bit depth — --depth 8|10|12. Default 8. Use 10 for HDR or 16-bit source.
6. Output dir — default: <input-dir>/avif/. Skill never overwrites originals.
7. Recursive — --recursive for directory descent.
8. Preserve EXIF — default off (web-prep assumption). --keep-exif to copy EXIF over via exiftool.

Procedure

1. Verify avifenc is on PATH. If missing, point at install-deps.

2. Enumerate inputs (jpg, jpeg, png, tiff — skip others with note).

3. For each file:

   avifenc -q <quality> -s <speed> [--lossless] [--depth <n>] "<input>" "<output>"
   

   Per-file. avifenc is single-threaded per encode but accepts --jobs N for tile-parallel — useful on large images. For batch parallelism, use xargs -P <ncpu>.

4. If --keep-exif was set, post-process:

   exiftool -tagsfromfile "<input>" -all:all "<output>" -overwrite_original
   

5. Track size deltas.

Output

• AVIF files at <output-dir>/.
• Summary:
  • Files processed / failed.
  • Total: <orig-MB> → <new-MB> (<pct>% saved).
  • Quality estimate per file (using --qcolor if requested).

Notes

• AVIF encoding is slow compared to JPEG/WebP. Speed 6 is ~2–4× slower than cwebp. Speed 0 can be 30× slower. Pick 6 unless archiving.
• --speed 6 --quality 60 is the de facto web-prep default — quality matches q82 JPEG at roughly half the bytes.
• Animation: avifenc supports animated AVIF from PNG sequences (avifenc -i input1.png -i input2.png ...) but this skill focuses on still images.
• Decode support outside browsers is uneven (older image viewers may not decode). Check before mass-converting an archive.
• For guaranteed lossless re-encode of a JPEG (bit-exact reversible), use convert-to-jxl instead — JXL has a unique lossless-JPEG mode.