D-9 HD is a 100 Mbps version of D-9, used for recording compressed and subsampled HDTV. The compression scheme is DCT (Discrete Cosine Transform) and uses a mild 3:3:1 intraframe compression. Like standard D-9, D-9 HD uses parallel recording which employs twice the number of heads as D-9. It supports eight independently editable audio channels, making it suitable for surround sound audio editing as well as multi-language dubbing. D-9 HD uses the same tape as D-9 and previously recorded 50 Mbps D-9 tapes can play back on the D-9 HD VTRs.