Dolby Laboratories DP570 - Manual (Page 102)

90 Dolby ® DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata Downmixing
• Film Standard
Max Boost: 6 dB (below –43 dB)
Boost Range: –43 to –31 dB (2:1 ratio)
Null Band Width: 5 dB (–31 to –26 dB)
Early Cut Range: –26 to –16 dB (2:1 ratio)
Cut Range: –16 to +4 dB (20:1 ratio)
• Music Light
(No early cut range)
Max Boost: 12 dB (below –65 dB)
Boost Range: –65 to –41 dB (2:1 ratio)
Null Band Width: 20 dB (–41 to –21 dB)
Cut Range: –21 to +9 dB (2:1 ratio)
• Music Standard
Max Boost: 12 dB (below –55 dB)
Boost Range: –55 to –31 dB (2:1 ratio)
Null Band Width: 5 dB (–31 to –26 dB)
Early Cut Range: –26 to –16 dB (2:1 ratio)
Cut Range: –16 to +4 dB (20:1 ratio)
• Speech
Max Boost: 15 dB (below –50 dB)
Boost Range: –50 to –31 dB (5:1 ratio)
Null Band Width: 5 dB (–31 to –26 dB)
Early Cut Range: –26 to –16 dB (2:1 ratio)
Cut Range: –16 to +4 dB (20:1 ratio)
• None
No DRC profile selected. The dialogue level parameter (dialnorm) is still applied.
These choices are available to the content producer for both Line mode and RF mode. The
content producer chooses which of these profiles to assign to each mode; when the
consumer or decoder selects a DRC mode, the profile chosen by the producer is applied.
In addition to the DRC profile, metadata can limit signal peaks to prevent clipping during
downmixing. This metadata, known as overload protection, is inserted by the encoder only
if necessary. For example, consider a 5.1‐channel program with signals at digital full‐scale
on all channels being played through a stereo, downmixed line‐level output. Without some
form of attenuation or limiting, the output signal would obviously clip. Correct setting of
the Dialogue Level and DRC profiles normally prevents clipping and unnecessary
application of automatic overload protection.
D.5 Downmixing
Downmixing is a function of Dolby Digital that allows a multichannel program to be
reproduced over fewer speaker channels than the number for which the program is
optimally intended. Simply put, downmixing allows consumers to enjoy a DVD or digital
television broadcast without requiring a full‐blown home theater setup.
Note: DRC profile settings are dependent on an accurate dialogue level setting. Improper
setting of the dialogue level parameter may result in excessive and audible
application of overload‐protection limiting.