AVIF and MIAF: How the Formats Are Related

The AV1 Image File Format (AVIF) and the Multi-Image Application Format (MIAF) share an architectural relationship where MIAF serves as the foundational structural profile for AVIF. While AVIF defines how state-of-the-art AV1-compressed image data is packaged, MIAF establishes the standardized container constraints and metadata rules that AVIF follows. In essence, an AVIF file is an implementation of MIAF that utilizes AV1 video compression for its visual payload, ensuring both high compression efficiency and universal container interoperability.

The Container Hierarchy: From ISOBMFF to AVIF

To understand the connection between AVIF and MIAF, it is essential to trace the lineage of modern media containers:

1. ISOBMFF (ISO Base Media File Format): The universal root standard (ISO/IEC 14496-12) used to structure multimedia files using discrete data blocks called "boxes."
2. HEIF (High Efficiency Image File Format): An extension of ISOBMFF (ISO/IEC 23008-12) designed for storing still images, image collections, image sequences, and associated metadata.
3. MIAF (Multi-Image Application Format): A constrained application profile of HEIF (ISO/IEC 23000-22) created to simplify HEIF implementation across hardware and software platforms.
4. AVIF (AV1 Image File Format): A format developed by the Alliance for Open Media (AOMedia) that maps the AV1 bitstream directly into the MIAF-constrained container structure.

What MIAF Solves

The base HEIF standard is broad and flexible, offering numerous optional configurations that can lead to software fragmentation and decoding errors. MIAF was standardized by MPEG to solve this problem. It applies precise constraints on HEIF files, standardizing:

• Pixel aspect ratios and dimensions.
• Supported color representations, such as explicit requirements for High Dynamic Range (HDR), Wide Color Gamut (WCG), Rec. 709, and standard ICC or NCLX profiles.
• Standardized handling of alpha channels for transparency.
• Unified methods for storing auxiliary images (such as depth maps).
• Mandatory integration formats for metadata, strictly regulating Exif and XMP data packaging.
• Structural rules for image transformations, such as rotation and mirroring, avoiding unnecessary re-encoding.

How AVIF Adopts MIAF

When AOMedia developed AVIF, rather than inventing a completely new container architecture, they designed AVIF as a specialized implementation of MIAF.

The official AVIF specification explicitly requires that compliant AVIF files adhere to the structural rules defined in the MIAF standard. In this pairing:

• MIAF provides the skeleton: It manages file navigation, metadata parsing, transparency channels, color management parameters, and sequence timing.
• AV1 provides the flesh: The actual visual pixels are compressed using the open, royalty-free AV1 codec instead of traditional codecs like AVC or HEVC.

AVIF files indicate MIAF compliance directly in their file type box (ftyp). A standard AVIF file typically includes the major brand avif alongside compatible brands such as mif1 (HEIF) and miaf.

Practical Implications

Because AVIF relies on MIAF, developers and hardware manufacturers do not need to build parsers from scratch to support AVIF files. Any software or decoder pipeline capable of reading standard MIAF metadata and container structures only needs an added AV1 decompression block to fully decode AVIF. This structural alignment dramatically accelerates cross-browser adoption, operating system support, and hardware acceleration for AVIF on the modern web.