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Image MIME Reference
AVCI

AVC Image (HEIF Container)

image/avci
VS

AirZip Accelerator Image

image/vnd.airzip.accelerator.azv
AZV

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

Equal browser support

Feature Support

Feature AVCI AZV
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
AVC Image (HEIF Container)
image/avci
Extension
.avci.hif
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 69
Full AVCI reference →
AirZip Accelerator Image
image/vnd.airzip.accelerator.azv
Extension
.azv
Container Proprietary AirZip Container
Compression Lossy (Proprietary) / Lossless (Proprietary)
Algorithm
AirZip Proprietary Compression
Color Depth 8-bit (Indexed), 24-bit (RGB)
Developed by AirZip, Inc.
Released 1999
Magic Bytes
Unknown (Proprietary)
Full AZV reference →

Browser Support Comparison

Browser AVCI AZV
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
AVCI

AVCI Strengths

  • 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.
AZV

AZV Strengths

  • Historically allowed internet users to browse the web up to 5x faster over 56k dial-up modems by drastically reducing image payload sizes
  • Officially registered in the IANA vendor tree, preventing MIME type conflicts on early web proxy servers
Limitations
  • Completely obsolete in the modern broadband era
  • Closed-source and proprietary, meaning no modern image manipulation libraries (like ImageMagick or libvips) can decode it
  • Zero support in standard web browsers

When to choose which format

AVCI
Use AVCI when…
  • Digital Photography
  • Camera Capture
  • Archival Storage
AZV
Use AZV when…
  • Dial-up Web Acceleration
  • Bandwidth Optimization (Historical)
  • Legacy Proxy Servers

More comparisons

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