5.6.7 Issues with DVD Audio (DVD-A)

5.6.7.1 DVD audio delivers 6 channels of audio at the 24 bit 96 kHz standard, and/or two channels at 24 bit 192 kHz, however digital outputs on most DVD players are limited to 16 bit 48 kHz resolution as a piracy control measure. The DVD forum has selected IEEE1394 (firewire) as the preferred digital interface for DVD Audio, using the “Audio and Music Data Transmission Protocol” (A&M protocol) (http://www.dvdforum.com/images/guideline1394V09R0_20011009c.pdf).

5.6.7.2 Decoding compressed formats such as MLP can be done by the player or at a later processing stage. Discs may include alternative versions or additional content including down mixing of surround signals to stereo, alternative tracks, accompanying video etc, requiring a policy decision as to whether all these versions are to be collected or if not which alternatives are required for the archive. It is also important that archive staff be aware that hybrid discs,such as those recorded in compliance with the Blue Book standard as Enhanced CDs, may contain other data. The extra graphical or textual data may be critical components of the work and are therefore necessary in acquiring and preserving the content.