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Image MIME Reference
JPEG-XR-(HEIF)

JPEG XR Image (HEIF Container)

image/jxra
VS

RealNetworks RealFlash

image/vnd.rn-realflash
RealFlash

A complete technical comparison of JPEG XR Image (HEIF Container) and RealNetworks RealFlash — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature JPEG-XR-(HEIF) RealFlash
Transparency (Alpha) Yes Yes
Animation Support ✕ No Yes
Progressive Loading Yes Yes
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG XR Image (HEIF Container)
image/jxra
Extension
.jxra
Container HEIF / ISOBMFF (ISO/IEC 23008-12 / Annex F of ITU-T T.832)
Compression Lossy / Lossless
Algorithm
JPEG XR (Lapped Biorthogonal Transform)
Color Depth 8-bit, 16-bit, 32-bit (Float)
Developed by ISO/IEC JTC 1 / ITU-T
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 78 72 41
Full JPEG-XR-(HEIF) reference →
RealNetworks RealFlash
image/vnd.rn-realflash
Extension
Container RealMedia / SWF
Compression Vector (Flash) / RealAudio Compression
Algorithm
Macromedia Vector CompressionDeflate (Zlib)
Color Depth 8-bit, 24-bit, 32-bit
Developed by RealNetworks & Macromedia
Released 1997
Magic Bytes
46 57 53 (FWS - Standard Flash) or 2E 52 4D 46 (.RMF - RealMedia Container)
Full RealFlash reference →

Browser Support Comparison

Browser JPEG-XR-(HEIF) RealFlash
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
JPEG-XR-(HEIF)

JPEG-XR-(HEIF) Strengths

  • Combines the deep color (32-bit float) and mathematically lossless compression of JPEG XR with the robust metadata architecture of HEIF
  • Allows grouping multiple images, exposure brackets, or focal stacks into a single file collection
Limitations
  • Practically non-existent software and operating system support compared to standard HEIC or legacy JPEG XR (.jxr)
  • Zero web browser support, rendering it entirely unsuitable for public web deployment
  • Eclipsed by modern standards like AVIF and JPEG XL which offer superior compression with much broader industry backing
RealFlash

RealFlash Strengths

  • Allowed complex, interactive vector animations to stream smoothly over 28.8k dial-up modems
  • Perfectly synchronized streaming audio with timeline-based animations, which was revolutionary in 1997
Limitations
  • Heavily reliant on proprietary browser plugins (RealPlayer), which were notoriously bloated
  • Completely obsolete and unsupported on the modern web
  • Tightly coupled server-client architecture required expensive RealServer licenses to host

When to choose which format

JPEG-XR-(HEIF)
Use JPEG-XR-(HEIF) when…
  • Specialized Archival
  • Experimental Imaging Workflows
  • High Dynamic Range (HDR) Imaging
RealFlash
Use RealFlash when…
  • Historical Dial-up Web Animation
  • Late-1990s Interactive Music Videos
  • Streaming Vector Graphics

More comparisons

JPEG-XR-(HEIF) vs ACES → RealFlash vs ACES → JPEG-XR-(HEIF) vs APNG → RealFlash vs APNG → JPEG-XR-(HEIF) vs AVCI → RealFlash vs AVCI → JPEG-XR-(HEIF) vs AVCS → RealFlash vs AVCS → JPEG-XR-(HEIF) vs AVIF → RealFlash vs AVIF → All comparisons →
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