DigiCipher II uses QPSK and BPSK at the same time. The primary difference between DigiCipher 2 and DVB lies in how each standard handles SI
metadata, or System Information, where DVB reserves packet identifiers from 16 to 31 for metadata, DigiCipher reserves only packet identifier 8187 for its
master guide table which acts as a
look-up table for all other metadata tables. DigiCipher 2 also extends the MPEG
program number that is assigned for each service in a transport stream with the concept of a
virtual channel number, whereas the DVB system never defined this type of remapping preferring to use a registry of
network identifiers to further differentiate
program numbers from those used in other transport streams. There are also private non-standard additions to DVB that add virtual channel remapping using
logical channel numbers. Also unlike DVB, all text used in descriptors can be compressed using standard
Huffman coding which saves on broadcast bandwidth and loading times. DigiCipher II uses
Dolby Digital AC-3 audio for all channels, although MPEG-1 Level 2 audio is not supported. ==External links==