HV30

From CHDK Wiki

HD camcorder based on the HV20, the HV30 offers some physical body improvements as well as a new shooting mode "30p" or (30 fps, true progressive).

Analyzing the differences in firmware between the HV20 and HV30 would be a very good start, since the interior hardware appears identical between the two camcorders, and the firmware versions should be identical apart from the new 30p mode.