Free webp to jpg
EN
Image MIME Reference
AVCS

AVC Image Sequence (HEIF Container)

image/avcs
VS

Extended Image File Format

image/vnd.xiff
XIFF

A complete technical comparison of AVC Image Sequence (HEIF Container) and Extended Image File Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature AVCS XIFF
Transparency (Alpha) Yes ✕ No
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
AVC Image Sequence (HEIF Container)
image/avcs
Extension
.avcs.heifs
Container HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression Lossy / Lossless
Algorithm
AVC (Advanced Video Coding / H.264)
Color Depth 8-bit, 10-bit, 12-bit
Developed by Moving Picture Experts Group (MPEG) / ISO/IEC JTC 1
Released 2015
Magic Bytes
XX XX XX XX 66 74 79 70 61 76 63 73
Full AVCS reference →
Extended Image File Format
image/vnd.xiff
Extension
.xif
Container TIFF-based Proprietary Container
Compression CCITT Group 3 / Group 4 / LZW / Uncompressed
Algorithm
CCITT Group 4LZWNone
Color Depth 1-bit (Monochrome), 8-bit (Grayscale), 24-bit (RGB)
Developed by Keyfile Corporation
Released 1994
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Full XIFF reference →

Browser Support Comparison

Browser AVCS XIFF
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
AVCS

AVCS Strengths

  • 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  • Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)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
XIFF

XIFF Strengths

  • Pioneered early enterprise document workflow integration by binding administrative routing data directly to the document image file
  • Leveraged efficient fax compression standards to keep storage requirements low on 1990s server infrastructure
Limitations
  • Completely proprietary and obsolete; Keyfile Corporation's software ecosystem no longer exists
  • Causes widespread MIME type identification conflicts due to sharing the exact same binary header signature as standard TIFF files
  • Zero support in modern operating systems or web browsers

When to choose which format

AVCS
Use AVCS when…
  • Burst Photography
  • Short Animations
  • Camera Capture
  • Archival Storage
XIFF
Use XIFF when…
  • Keyfile Enterprise Document Management
  • Legacy Corporate Workflow Archival
  • Scanned Multi-page Document Routing

More comparisons

AVCS vs ACES → XIFF vs ACES → AVCS vs APNG → XIFF vs APNG → AVCS vs AVCI → XIFF vs AVCI → AVCS vs AVIF → XIFF vs AVIF → All comparisons →
Share this comparison