CBHD Technical Specifications
Physical disc geometry
CBHD kept the 12 cm diameter and the DVD-like structure of two 0.6 mm polycarbonate substrates bonded back to back, giving a 0.6 mm cover layer above the data layer. It did not adopt Blu-ray’s thinner 0.1 mm cover and 0.85 NA lens. Physically the disc resembles an HD DVD disc. Optical readout uses a head capable of differential phase detection tracking.
CHDA comparison: CBHD vs DVD vs Blu-ray
| Parameter | CBHD | DVD | Blu-ray |
|---|---|---|---|
| Laser | 405 nm | Red (650 nm) | 405 nm |
| Numerical aperture | 0.65 | 0.60 | 0.85 |
| Single layer | 15 GB | 4.7 GB | 25 GB |
| Dual layer | 30 GB | 8.5 GB | 50 GB |
| Maximum resolution | 1080p | 576p | 1080p |
| Track pitch | 0.40 μm | 0.74 μm | 0.32 μm |
| Minimum pit | 0.204 μm | ~0.40 μm | ~0.149 μm |
| Modulation | 4-6 FSM | EFM(+) | BD modulation |
| File system | UDF | UDF | UDF |
| 1× data rate | 36.55 Mbps | – | – |
| Max video bitrate | 28 Mbps | – | – |
CBHD vs HD DVD vs Blu-ray (codec and DRM view)
| Parameter | CBHD | HD DVD | Blu-ray |
|---|---|---|---|
| Cover substrate | 0.6 mm | 0.6 mm | 0.1 mm |
| Primary video | AVS (GB/T 20090.2) | VC-1, H.264, MPEG-2 | H.264, VC-1, MPEG-2 |
| Primary audio | DRA (GB/T 22726) | DD+, DTS-HD, LPCM | TrueHD, DTS-HD MA, LPCM |
| Copy protection | DKAA / AACS derivative | AACS | AACS, BD+ |
| Navigation | CETC | Advanced Content (iHD/XML) | HDMV / BD-J |
Laser wavelength, NA, track pitch, minimum pit length and capacities match HD DVD’s physical envelope. Error-correction details remain undocumented across the research passes. Early presumption that CBHD matched HD DVD’s NA 0.65 and 0.40 μm pitch was later confirmed from the archived CHDA technical page.
Why DVD factories could convert
Because recording-layer geometry stayed close to DVD, Chinese plants could modify existing DVD lines instead of building a Blu-ray production ecosystem. Plants in Shanghai, Shenzhen and Guangzhou needed upgrades such as a 405 nm mastering laser and spin-coater retrofits for denser pit geometry. A secondary unverified source puts line conversion near US$800,000 versus about $3 million for Blu-ray. Memory-Tech independently confirmed the strategy and built a complete CBHD production system through UOD.
Modulation: 4-6 FSM
CBHD replaced HD DVD’s 8-12 ETM with 4-6 FSM. Chinese industry reporting (Sina Tech, 3 April 2009) names this as one of three major changes, made “to add Chinese patents.” The Shinco CBHD-9100 specification advertises China’s proprietary 4-6 modulation coding. A 2008 Gizmodo piece described a CH-DVD player as essentially an HD DVD player “whose laser is set at a different modulation,” able to share processors and optical pickups in manufacturing.
The VCD analogy breaks here. VCD could be authored onto CD-R with ordinary burners. A pressed CBHD needs correct logical structure, premaster, CBHD physical encoding with 4-6 modulation, error-correction/channel structure, blue-laser mastering and replication. A DVD burner cannot simply be told to “burn this CBHD ISO”: the disc may be UDF, but UDF is not the physical format. A later Novatek servo DSP (NT90912) supported FSM alongside ETM, EFM+ and EFM, showing dedicated hardware support for the channel.
File system and disc structure
Chinese comparison tables explicitly identify UDF, which makes preservation more tractable than inventing a file system from zero. Descriptions of what sits on top of UDF differ between research passes:
- Exact UDF version and containers not verified; UDF 2.5 and EVO/MPEG-PS are likely but unconfirmed given HD DVD derivation.
- The DCA verifier validates China HD content against HD DVD Book 3 1.x with supplemental information, including EVOB, HDi content, Full Trust and Restricted Mode-implying HD DVD logical structures with Chinese extensions.
- Another model places elementary AVS video and DRA audio in MPEG-2 Transport or Program Streams under a CBHD_TS volume directory (or HVDVD_TS on early CH-DVD transition discs), with a CBHD_TS.IFO stream map.
None of the passes cites a directory dump of a real CBHD disc. Relatively understood items include UDF as the filesystem label, 12 cm geometry, 15/30 GB capacity, 405 nm / 0.65 NA, 4-6 FSM as a concept, and the codec list. Still requiring direct disc investigation: exact UDF layout, directory conventions, EVOB usage, playlist and navigation files, CETC implementation details, DKAA structures and keys, sector-level differences, lead-in/lead-out, error correction, and exact Book 2 / Book 3 relationship to HD DVD.
Three software layers on a commercial disc
- Application: media assets and scripts; video in AVS; audio in DRA or LPCM; menus and multi-angle via CETC.
- Container / system stream: AVS and DRA elementary streams multiplexed into MPEG-2 TS or PS under CBHD_TS.
- Cryptographic protection: DKAA between UDF and decoders; authenticity checks; key exchange with player hardware; HDCP over HDMI.
CETC navigation
CBHD replaced HD DVD’s Advanced Content (HDi/iHD-XML, ECMAScript and SMIL) with CETC navigation. CHDA material lists dual highlight regions in menus, preview/summarised content, audio associated with the highlighted selection, and DVD-like multi-angle, multiple audio and subtitle tracks. The design kept some DVD-like interface behaviour without a Java virtual machine (unlike Blu-ray BD-J) or heavy XML parsers. A first-generation CETC bug on the Shinco HD-3700U caused pause on native CBHD to break frame sync; the TCL THBD-1038 is described as carrying an updated CETC engine. Even with UDF, video, audio and subtitles in hand, a playable CBHD still needs the CETC environment the player expects.
Video and audio codecs
Official CHDA documentation lists AVS, H.264/AVC, VC-1 and MPEG-2; player specs made AVS, MPEG-4 AVC and VC-1 mandatory. Player lists:
- Shinco CBHD-9100: AVS-Video, VC-1, MPEG-4, AVC; JPEG; outputs 1080p/i, 720p, 480p.
- TCL THBD-1008: VC-1, H.264, MPEG-4, MPEG-2; 1080p/24.
- Shinco HD-3700U: AVS, MPEG-2, DVD-Video, EVD, HVD, SVCD, VCD; AVI from USB.
Early 2009 discs almost certainly used VC-1 or AVC because AVS encoders were not yet available at China Record; AVS and DKAA discs were presented as a “new generation” only in September 2009. One research pass states video was encoded exclusively in AVS; others say discs could and early discs likely did use VC-1/AVC.
AVS Part 2 video became national standard GB/T 20090.2-2006 in February 2006 after working-group work from 2002. AVS1 is a full system-system, video, audio, DRM and compliance-not only a video codec. Technical traits cited for CBHD use: efficiency comparable to H.264 High Profile with lower complexity; licensing about 1 RMB per decoder; 8×8 integer transforms, quarter-pel motion vectors, context-adaptive spatial prediction and its own loop filter; typical encodes 1080p at 23.976/24 fps or 1080i at 50 Hz, averages 12-18 Mbps.
Official audio lists AVS Audio, DRA and Dolby AC-3. Shinco CBHD-9100 adds LPCM and 5.1 output. TCL THBD-1008 lists Dolby Digital, Digital Plus, TrueHD and PCM. DRA is standardised as SJ/T 11368-2006 and GB/T 22726-2008 (DigiRise / Guangzhou Digital Rise Technology); optional in Blu-ray from version 2.3. Expansions of the acronym differ: “Dynamic Resolution Adaptation” versus “Digital Rise Audio.” Multi-channel sub-band/MDCT coding from mono/stereo to 5.1/7.1 and bitrates from 64 kbps to 1.5 Mbps are reported. CBHD-HiFi (July 2010) used dual-layer 30 GB for multi-channel LPCM up to 24-bit/192 kHz over secure HDMI; China Record music documentaries appear as HiFi special editions.
DKAA, AACS, region and packaging
CBHD-3D specifications and products launched in Beijing in July 2010; by that month only one 3D title existed; Guangzhou Asian Games ceremonies were planned for 3D release. What Hi-Fi covered the move under the headline that HD-DVD was “back” in 3D. Packaging used black Blu-ray-size cases originally designed for HD-VMD, carrying a blue CBHD logo; the DVD Forum’s “HD DVD China” logo had been approved in November 2007. Region coding remains poorly attested across passes.
Understood versus still needing a disc
ChatGPT pass 2’s checklist remains the practical guide for laboratory work. Relatively understood: UDF as the labelled filesystem, twelve-centimetre geometry, 15/30 GB capacities, 405 nm laser, 0.65 NA, 4-6 FSM as a concept, AVS and the Western video codecs, DRA and Dolby AC-3, and the existence of CETC and DKAA as named systems. Still requiring direct disc investigation: exact CBHD UDF layout and identifiers, directory conventions, exact EVOB usage, playlist structure, navigation files and CETC binaries, DKAA structures and keys, sector-level differences from HD DVD, lead-in/lead-out implementation, error-correction details, and the precise relationship between CBHD Books 2/3 and HD DVD Books 2/3. Owning an actual CBHD disc therefore becomes extremely valuable for reconstruction.
Understood versus still needing a disc on the bench
ChatGPT pass 2’s checklist remains the practical guide for laboratory work. Relatively understood: UDF as the labelled filesystem, twelve-centimetre geometry, 15/30 GB capacities, 405 nm laser, 0.65 NA, 4-6 FSM as a concept, AVS and the Western video codecs, DRA and Dolby AC-3, and the existence of CETC and DKAA as named systems. Still requiring direct disc investigation: exact CBHD UDF layout and identifiers, directory conventions, exact EVOB usage, playlist structure, navigation files and CETC binaries, DKAA structures and keys, sector-level differences from HD DVD, lead-in/lead-out implementation, error-correction details, and the precise relationship between CBHD Books 2/3 and HD DVD Books 2/3. Owning an actual CBHD disc is extremely valuable for reconstruction.
Packaging used black Blu-ray-size cases originally designed for HD-VMD, carrying a blue CBHD logo. The DVD Forum’s separate “HD DVD China” logo had been approved in November 2007. Region coding remains poorly attested. Domestic films used DKAA; international films used AACS.
Further reading on historic video formats
If you want to learn more about historic video formats, get The History of Physical Video Formats from the Frontier by Stephen Driver on Amazon: