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Image MIME Reference
AVCS

AVC Image Sequence (HEIF Container)

image/avcs
VS

BlockFact Image

image/vnd.blockfact.facti
FACTI

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

Equal browser support

Feature Support

Feature AVCS FACTI
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
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 →
BlockFact Image
image/vnd.blockfact.facti
Extension
.facti
Container BlockFact Authenticated Container
Compression Container (Inherits payload compression, e.g., JPEG/PNG)
Algorithm
None (Pass-through to embedded payload)
Color Depth Inherited from payload
Developed by BlockFact
Released 2025
Magic Bytes
Unknown (Proprietary Container)
Full FACTI reference →

Browser Support Comparison

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  • Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)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

FACTI Strengths

  • Provides undeniable, mathematically verifiable proof of a photo's origin (time, location, and device) via the StarkNet blockchain [1.3.1]
  • Privacy-first design utilizes zero-knowledge proofs (Groth16), meaning the actual image is never uploaded to a central server or blockchain
  • Invisible watermarking ensures that even if the image is screenshotted or cropped, tampering can be detected
Limitations
  • Lacks native rendering support in web browsers and standard image viewers, requiring specialized software to view
  • Requires blockchain registration at the moment of capture, making it incompatible with existing legacy photos
  • The proprietary nature of the container limits integration to environments supporting the BlockFact SDK

When to choose which format

AVCS
Use AVCS when…
  • Burst Photography
  • Short Animations
  • Camera Capture
  • Archival Storage
FACTI
Use FACTI when…
  • Journalism and Media Authentication
  • Legal and Insurance Evidence
  • AI Deepfake Prevention
  • Content Provenance and Authorship

More comparisons

AVCS vs ACES → FACTI vs ACES → AVCS vs APNG → FACTI vs APNG → AVCS vs AVCI → FACTI vs AVCI → AVCS vs AVIF → FACTI vs AVIF → All comparisons →
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