Image MIME Reference
DVB-SUB
DVB Subtitle
image/vnd.dvb.subtitle
VS
JPEG 2000 Compound Image File Format
image/jpm
JPM
A complete technical comparison of DVB Subtitle and JPEG 2000 Compound Image File Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | DVB-SUB | JPM |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | Yes |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | ✕ No | Yes |
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
JPEG 2000 Compound Image File Format
image/jpm
Extension
.jpm.jpgm
Container
ISOBMFF / JPM (ISO/IEC 15444-6)
Compression
Lossy / Lossless / Mixed Raster Content (MRC)
Algorithm
JPEG 2000JBIG2JPEGMMR
Color Depth
1-bit (Text/Masks), 8-bit, 16-bit, 24-bit
Developed by
Joint Photographic Experts Group (JPEG)
Released
2003
Magic Bytes
00 00 00 0C 6A 50 20 20 0D 0A 87 0A ... 66 74 79 70 6A 70 6D 20
Browser Support Comparison
| Browser | DVB-SUB | JPM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
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
JPM
JPM Strengths
- Highly optimized for scanned documents, drastically reducing file sizes without sacrificing the readability of text or the quality of embedded photos
- Supports multi-page documents within a single file
- Object-based architecture allows for complex layout representation and independent extraction of elements
Limitations
- Failed to achieve widespread adoption, largely being overshadowed by PDF/A and DjVu
- Zero native web browser compatibility
- Requires complex, specialized software to properly encode and decode the multi-layered MRC structure
When to choose which format
DVB-SUB
Use DVB-SUB when…
- Digital Television Broadcasts (DVB-T, DVB-S, DVB-C)
- IPTV and OTT Streaming
- Hardware Set-top Boxes
JPM
Use JPM when…
- Scanned Document Archiving
- Mixed Raster Content (MRC) Imaging
- Digital Libraries