AVCS

AVC Image Sequence (HEIF Container)

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

AVCS (Advanced Video Coding Image Sequence) is a format that stores a sequence of images, such as burst photography or short animations, encoded with the AVC (H.264) codec within a High Efficiency Image File Format (HEIF) container.

Photography & Professional Transparency Animation ✦ HDR Production Ready

Technical Specifications

MIME Type

image/avcs

Extensions

.avcs.heifs

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-sequence

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

XX XX XX XX 66 74 79 70 61 76 63 73

ASCII: ....ftypavcs

HTTP Headers

Content-Type: image/avcs

HTML Accept Attribute

accept="image/avcs, .avcs, .heifs"

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

Efficiently stores bursts of images or animations utilizing inter-frame compression
Leverages the highly compatible and widely hardware-accelerated AVC (H.264) codec
Robust HEIF container supports extensive metadata, alpha channels, and depth maps

Limitations

Zero native support in web browsers
Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)
Complicated container structure requires specialized parsing libraries

Developer Code Snippets

import magic
print(magic.from_file('burst.avcs', mime=True)) # May output 'image/avcs' or 'image/heif-sequence'

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

import "net/http"

mimeType := http.DetectContentType(fileBytes)
// Go standard library lacks HEIF sequence detection; ISOBMFF parsing is required

$mime = mime_content_type('burst.avcs');
echo $mime; // Standard magic database may lack specific 'avcs' signatures

File Detection Steps

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

1 Check for ISOBMFF 'ftyp' box starting at byte offset 4
2 Verify 'avcs' 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

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

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/avcs/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="AVCS 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/avcs.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 difference between image/avci and image/avcs?

While both use the AVC (H.264) codec inside a HEIF container, image/avci is used for single still images, whereas image/avcs is used for an image sequence (such as an animation or a camera burst).

What is the magic byte for AVCS?

AVCS uses the standard ISOBMFF container structure. The signature begins with a 4-byte box size, followed by the 'ftyp' identifier, and then the 'avcs' brand. The hex representation is XX XX XX XX 66 74 79 70 61 76 63 73.

Can I use AVCS for web animations instead of GIF or WebP?

No, AVCS is not supported natively by web browsers. For web animations, formats like Animated WebP, AVIF, APNG, or standard MP4 video are strongly recommended.