DVCPRO HD (aka DVCPRO 100) has four codecs working in parallel and a coded video bitrate operating to about 100 Mbit/s, and runs to a 4:2:2 format.
HD Camcorders
The HD camera down samples native 720p/1080i signals to a lower resolution. 720p is down sampled from 1280x720 to 960x720 and 1080i is down sampled from 1920x1080 to 1280x1080 for 59.94i and 1440x1080 for 50i. This is a common technique, utilised in most tape-based HD formats such as HDCam and HDV. Compression ratio is approximately 6.8:1.
Extended Recording Time
To maintain compatibility with HDSDI, DVCPRO100 equipment internally down samples video during recording and subsequently up samples video during playback. A camcorder using a special variable-frame rate (from 4 to 60 frame/s) variant of DVCPRO HD called VariCam is also available. All of these variants are backward compatible but not forward compatible. A DVCPRO HD EX format is also available which runs the tape at slower speed, resulting in recording times that are twice as long.