Image MIME Reference
AVCS
AVC Image Sequence (HEIF Container)
image/avcs
VS
DVB Subtitle
image/vnd.dvb.subtitle
DVB-SUB
A complete technical comparison of AVC Image Sequence (HEIF Container) and DVB Subtitle — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | AVCS | DVB-SUB |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| 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
DVB Subtitle
image/vnd.dvb.subtitle
Extension
.sub.sup.ts
Container
MPEG-2 Transport Stream (MPEG-TS) PES Packets
Compression
Lossless (Run-Length Encoding)
Algorithm
RLE (Run-Length Encoding)
Color Depth
2-bit (Indexed), 4-bit (Indexed), 8-bit (Indexed CLUT)
Developed by
DVB Project (ETSI)
Released
1997
Magic Bytes
20
Browser Support Comparison
| Browser | AVCS | DVB-SUB |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
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- Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)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
DVB-SUB
DVB-SUB Strengths
- Guarantees 100% accurate visual representation (fonts, colors, layouts) exactly as intended by the broadcaster
- Effortlessly supports complex character sets (e.g., Arabic, Asian languages) without relying on the client device possessing the necessary fonts
- Supports region-specific dynamic positioning to avoid obscuring important on-screen graphics or burned-in lower thirds
Limitations
- Requires significantly more bandwidth than text-based subtitles
- Inaccessible to screen readers and cannot be indexed by search engines
- Requires OCR (Optical Character Recognition) to translate back into standard text-based web formats
- Zero native support in HTML5 video elements
When to choose which format
AVCS
Use AVCS when…
- Burst Photography
- Short Animations
- Camera Capture
- Archival Storage
DVB-SUB
Use DVB-SUB when…
- Digital Television Broadcasts (DVB-T, DVB-S, DVB-C)
- IPTV and OTT Streaming
- Hardware Set-top Boxes