more about the HDV format

MPEG-2 compression relies on both inter and intra frame compression to achieve greater efficiency than Motion JPEG (M-JPEG), which is the approach taken by most digital videotape formats because editing is simpler when compression is applied to individual frames ( intra frame) rather than across multiple frames (inter frame). MPEG-2 minimizes the bandwidth requirements by creating what are called long groups of pictures (GOP) and applying very high rates of compression. HDV uses a 15 picture GOP that begins with an intra frame (I-Frame). The I-Frame contains all the information to reconstruct a complete picture. It’s similar to a frame compressed using M-J

The HDV format

JVC and Sony introduced low cost HDV camcorders during 2004 that record 1080i or 720p on mini-DV tape. HDV uses inter frame compression across multiple frames rather than within a single frame to record 1080 by 50i, 1080 by 60i or 720 by 30p at or below the 25 Mbps data rate of the DV format. HDV stores less than one fifth of the information on DVCPROHD. To accomplish this feat, HDV relies on MPEG-2 compression.