China Blue High-definition Disc China Blue High-definition Disc China Blue High-Definition (CBHD; ; alternatively "China High Definition DVD") is a high definition optical disc format announced in September 2007 by the Optical Memory National Engineering Research Center (OMNERC) of Tsinghua University in China. The format is a derivative of the HD DVD, a medium created by the DVD Forum designed to succeed regular DVDs. Although HD DVD was scrapped as a result of losing the format war to Blu-ray, CBHDs continued to be produced and marketed, though only in China. Originally called CH-DVD, CBHD is a joint venture between the DVD Forum and OMNERC.
Optical disc drive on personal computers was originally a batch-oriented task in that it required specialised authoring software to create an "image" of the data to record, and to record it to disc in the one session. This was acceptable for archival purposes, but limited the general convenience of CD-R and CD-RW discs as a removable storage medium. Packet writing is a scheme in which the recorder writes incrementally to disc in short bursts, or packets. Sequential packet writing fills the disc with packets from bottom up. To make it readable in CD-ROM and DVD-ROM drives, the disc can be "closed" at any