Dialnorm metadata sets a consistent program loudness reference in Dolby Digital, defaulting to -27 and running -31 (loudest) to -1

Dialnorm (dialog normalization) is a metadata parameter set while encoding Dolby Digital, intended to maintain a consistent dialog level from program to program so levels don’t jump between shows, commercials, or channels. Its scale runs from –31 to –1, where –31 is actually the loudest setting and the default is –27. Because –31 is loudest, an engineer encoding music sets Dialnorm to –31 for the loudest encode, or the client asks why the DVD is so quiet.

Examples

Encoding a music program for DVD, the engineer sets Dialnorm to –31 (the loudest setting) so playback isn’t attenuated relative to other content.

Assessment

What does Dialnorm communicate to a Dolby Digital decoder, what is its default value, and which end of its range is loudest?