What is HDV?
It is a common misconception that HDV and HD formats are the same. Simply put, HDV is a video format that uses the HD line resolution (1080i or 720p) in a highly compressed format: MPEG-2 Transport Stream. This creates a stream that is small enough (roughly 25 Mbps @1080i, 19Mbps@720p) to fit on a standard DV tape. In addition to the data compression of the MPEG-2 format, HDV does not store all of the data that full-resolution HD video has. For example, one form of uncompressed HD is a 1920 x 1080 interlaced frame, but the similar HDV spec stores a 1440 x 1080 interlaced video frame. This combination of MPEG compression with a reduced frame size keeps HDV more manageable while also keeping the quality of the video very high. This technology also makes HD video resolution much more affordable than ever before.

A common analogy used to compare HDV and HD is to compare uncompressed Standard Definition (SD) to an SD MPEG format such as that used for DVDs. An uncompressed SD file is very large file compared to the highly compressed MPEG format, but the can both be the same resolution (720 x 480 is a common example). This is a very similar relationship full HD video and HDV video has with each other.