AVCI

AVC Image (HEIF Container)

image/avci Released 2015 · by Moving Picture Experts Group (MPEG) / ISO/IEC JTC 1

AVCI (Advanced Video Coding Image) is a format that stores still images encoded with the Advanced Video Coding (AVC / H.264) codec inside a High Efficiency Image File Format (HEIF) container. It was developed to apply efficient modern video compression techniques to still photography.

Photography & Professional Transparency ✦ HDR Production Ready

Technical Specifications

MIME Type

image/avci

Extensions

.avci.hif

Container

HEIF / ISOBMFF (ISO/IEC 14496-12)

Compression

Lossy & Lossless

Algorithms

AVC (Advanced Video Coding / H.264)

Color Depth

8-bit, 10-bit, 12-bit

Metadata

EXIF XMP ICC

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/heif

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

XX XX XX XX 66 74 79 70 61 76 63 69

ASCII: ....ftypavci

HTTP Headers

Content-Type: image/avci

HTML Accept Attribute

accept="image/avci, .avci"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

Shares the robust, flexible HEIF container architecture that allows for rich metadata, HDR, and depth maps.
Backed by the highly ubiquitous AVC (H.264) codec, which is widely supported in hardware decoding.
Supports rectangular cropping and rotation metadata without needing to re-encode the pixel data.

Limitations

No native support within web browsers for HTML rendering.
Inferior compression efficiency when compared to newer container formats like HEIC (HEVC) or AVIF (AV1).
Easily confused with HEIC and AVIF, which use the same base ISOBMFF container.

Developer Code Snippets

import magic
print(magic.from_file('photo.avci', mime=True)) # May output 'image/avci' or 'image/heif' depending on libmagic configuration

const FileType = require('file-type');
const type = await FileType.fromFile('photo.avci');
console.log(type.mime); // image/avci

import "net/http"

mimeType := http.DetectContentType(fileBytes)
// Go standard library may misidentify HEIF variants; use specialized ISOBMFF parsers

$mime = mime_content_type('photo.avci');
echo $mime; // May return 'application/octet-stream' or 'image/heif' without updated magic databases

File Detection Steps

How to programmatically detect a image/avci file by reading its raw bytes:

1 Check for ISOBMFF 'ftyp' box starting at byte offset 4
2 Verify 'avci' brand string starting at byte offset 8

Software Support

A

Apple Photos (macOS/iOS)

ImageMagick

W

Windows Photos (with HEIF Extension)

Conversion Tools

Share & Embed

Markdown Badge

[![AVCI Format](https://freewebptojpg.com/mime/image/avci/badge.svg)](https://freewebptojpg.com/mime/image/avci)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/avci/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="AVCI Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/avci.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is the image/avci format?

The image/avci format is a still image encoded using the AVC (H.264) video codec, wrapped within the HEIF (High Efficiency Image File Format) container. It is defined in ISO/IEC 23008-12.

Is AVCI the same as HEIC?

No. While both use the HEIF container structure, HEIC uses the HEVC (H.265) codec for compression, whereas AVCI uses the older AVC (H.264) codec.

Do browsers support AVCI?

Native web browser support for AVCI is practically non-existent. However, certain operating systems like macOS and iOS support native viewing of .avci files at the system level.