The 40GB hard disk will be enough for 5.5 hours of AVCHD recording at its highest quality setting, resulting in an Anamorphic Resolution of 1440x1080 compressed at 15Mbps. This is 25% higher than the Bitrate allowed by Canon's DVD based HR10.
Unlike Compression schemes from Sony and Panasonic, Canon's implementation of AVCHD uses VBR compression, allowing complex scenes to have less compression applied than simple scenes.
Canon said a version of the Windows-only Corel (formerly Ulead) VideoStudio 11 will be included with this HG10 camcorder, which is good news for consumers since support for AVCHD in editing software isn't exactly a standard feature.
AVCHD is only one compression standard used for Hi-Def camcorders. Some use HDV, which is related to the DV compression used in most standard definition digital camcorders. With the storage requirements for even a small amount of Hi-Def video, AVCHD's more advanced compression seems to be gaining a lot of support among manufacturers.
Source: Gizmodo