HD DVD BD9 formats. HD Rec is an extension of the HD DVD format for recording HD content on regular red laser DVD-Rs/DVD-RWs using H.264/MPEG-4 AVC compression. It was approved by the DVD Forum on September 12, 2007 It is comparable to Blu-ray Disc's AVCREC. The China Blue High-definition Disc (CBHD), a high-definition optical disc format, was based upon the HD DVD format. Like the HD DVD, CBHD discs have a capacity of 15 GB single-layer and 30 GB dual-layer and can use existing DVD production lines. Unlike the HD DVD format, industry support for this format has grown steadily. HD DVD
CD and DVD writing speed the same 74-minute time-frame requires a higher data transfer rate. Almost all modern CD/DVD burning software supports a selection of speeds at which the writeable disc can be written. However, the option a user chooses only defines the theoretical maximum of disc burning process. There are other factors that influence the time taken for a disc to be written to: A higher writing speed results in a faster disc burn, but the optical quality may be lower (i.e. the disc is less reflective). If the reflectivity is too low for the disc to be read accurately, some parts may be