AV1 Image File Format (.avif)
ISO/IEC 標準AVIF is a next-generation open image format derived from the AV1 video codec, delivering cutting-edge compression efficiency, high dynamic range (HDR), and wide color gamuts.
AVIF を JPG に変換
無料のブラウザ内 AVIF から JPG へのコンバーター。お使いのデバイスでファイルを即座に変換します。
AVIFをオンラインで圧縮
ブラウザ内100%ローカル圧縮 — ファイルが外部サーバーに送信されることはありません
調査とメタデータ
オペレーティングシステムやファイル解析ツールは、先頭のバイナリバイトシーケンスを検査することで AVIF ファイルを識別します:
バイトレベルのヘッダーシグネチャ (マジックバイト)
オペレーティングシステムやファイル解析ツールは、先頭のバイナリバイトシーケンスを検査することで AVIF ファイルを識別します:
16進数シグネチャ (オフセット 4):
66 74 79 70 61 76 69 66ASCII表現: ftypavif
標準化: ISO/IEC 23000-22 (MIAF) / AOMedia Specification
技術仕様
| コンテナアーキテクチャ | ISO Base Media File Format (ISOBMFF / MP4 container architecture) |
| 圧縮 | AV1 intra-frame video compression with directional spatial prediction & tile divisions |
| バイトエンディアン | Big-Endian for ISOBMFF atom/box sizes and fourCC codes |
| 色空間 | BT.2020, DCI-P3, sRGB, Full ICC Profiles, NCLX Color Primaries |
| チャンネルと構造 | Monochrome, YUV 4:2:0, 4:2:2, 4:4:4, and auxiliary Alpha channel |
| 最大寸法 | 65,536 x 65,536 pixels per grid tile (unlimited via multi-tile composition) |
| 透過性 | Full 8, 10, or 12-bit alpha transparency channel |
| ストリーミングとプログレッシブ | Progressive rendering supported via multi-layer spatial tiling |
技術比較マトリックス: AVIF 対 競合製品
| 技術属性 | AVIF (現在) | WebP | JPEG | JPEG XL |
|---|---|---|---|---|
| Compression Efficiency | Highest compression efficiency for photographic imagery | Good (25%-35% over JPEG) | Baseline standard | High efficiency + lossless focus |
| Color Depth & HDR | 8, 10, 12-bit native HDR & BT.2020 color gamut | 8-bit sRGB only | 8-bit standard | Up to 32-bit floating point HDR |
| Encoding Speed | Slow / CPU-heavy (requires sophisticated AV1 heuristics) | Fast to moderate | Extremely fast | Moderate to fast |
| Licensing | Royalty-free Open Source (AOMedia) | Royalty-free (Google) | Free standard | Royalty-free (ISO) |
| Browser Support | 93%+ modern browsers (Chrome, Firefox, Safari, Edge) | 97%+ | 100% | Experimental in Chromium |
一般的な破損モードと16進数リカバリガイド
⚠️ AVIF file fails to render with error 'Invalid ISOBMFF container'.
根本原因: Missing or malformed 'ftyp' box or missing 'avif' brand identifier at offset 0x04.
復旧: Inspect file with MP4Box or hex editor to ensure bytes 4-11 contain 'ftypavif' or compatible brand 'mif1'.
セキュリティ分析とパーサー攻撃ベクトル
AVIF relies on complex AV1 video bitstream decoders (dav1d / libaom). Secure implementations isolate decoders in restricted sandboxes.
既知の攻撃ベクター
- Complex bitstream parsing exploits in AV1 arithmetic coding or film grain synthesis logic.
- Out-of-memory denial-of-service via huge multi-tile grid declarations.
防御的ベストプラクティス: Use modern sandboxed Rust decoders (ravif) or updated libavif with dav1d.
歴史的背景とマイルストーン
主な利点とメリット
- Industry-leading lossy compression efficiency (up to 50% smaller than JPEG and 20% smaller than WebP).
- Native 10-bit and 12-bit High Dynamic Range (HDR) and Wide Color Gamut (WCG) support.
- Backed by major tech giants (Google, Apple, Microsoft, Netflix, Mozilla) with zero royalty fees.
技術的な制限とデメリット
- Encoding is significantly more CPU-intensive and slower than JPEG or WebP.
- Requires modern hardware or updated operating systems for hardware-accelerated decode.
- Lossless mode is generally less efficient than PNG or WebP lossless for simple UI graphics.
興味深い技術トリビア
- AVIF is packaged inside the exact same ISOBMFF container structure used by MP4 video files.
- Netflix uses AVIF for their global catalog UI thumbnails, saving terabytes of daily network bandwidth.
- AVIF supports film grain synthesis, artificially generating pleasing texture without storing heavy high-frequency noise.
よくある技術的な質問
Is AVIF better than WebP?
For photographic images, AVIF offers substantially better compression than WebP (often 20% smaller at identical quality) and supports 10-bit and 12-bit HDR color. However, AVIF takes longer to encode than WebP.
Why does AVIF take longer to encode?
AVIF uses the AV1 video codec's intra-frame compression algorithms, which evaluate thousands of spatial prediction angles, transform block sizes (from 4x4 to 64x64), and loop filters to find the mathematically optimal compression.
Can AVIF replace JPEG for everyday web images?
Yes. All major web browsers (Chrome, Safari, Firefox, Edge) now support AVIF natively. Using AVIF with HTML5 '<picture>' fallbacks is an industry best practice.