Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 112)

96 Dolby ® DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata
Center Downmix Level
When the encoded audio has three front channels (L, C, R), but the consumer has only two
front speakers (left and right), this parameter indicates the nominal downmix level for the
Center channel with respect to the Left and Right channels. Dolby Digital decoders use this
parameter during downmixing in Lo/Ro mode when Extended BSI parameters are not
active.
Surround Downmix Level
When the encoded audio has one or more surround channels, but the consumer does not
have surround speakers, this parameter indicates the nominal downmix level for the
surround channel(s) with respect to the Left and Right front channels. Dolby Digital
decoders use this parameter during downmixing in Lo/Ro mode when Extended BSI
parameters are not active.
Dolby Surround Mode
This parameter indicates to a Dolby Digital decoding product that also contains a Dolby
Pro Logic decoder (for example, a 5.1‐channel amplifier) whether or not the two‐channel
encoded bitstream contains a Dolby Surround (Lt/Rt) program that requires Pro Logic
decoding. Decoders can use this flag to automatically switch on Pro Logic decoding as
required.
Table D-8 Center Downmix Level Settings and Definitions
Center Downmix Level
Setting Definition
0.707 (–3 dB) default The Center channel is attenuated 3 dB and sent to the
Left and Right channels.
0.596 (–4.5 dB) The Center channel is attenuated 4.5 dB and sent to the
Left and Right channels.
0.500 (–6 dB) The Center channel is attenuated 6 dB and sent to the
Left and Right channels.
Table D-9 Surround Downmix Level Settings and Definitions
Surround Downmix
Level Setting Definition
0.707 (–3 dB) default The Left Surround and Right Surround channels are each
attenuated 3 dB and sent to the Left and Right front channels,
respectively.
0.5 (–6 dB) Same as above, but the signal is attenuated 6 dB.
0 (–999 dB) The surround channel(s) are discarded.
Table D-10 Dolby Surround Mode Settings and Definitions
Dolby Surround Mode
Setting Definition
Not Dolby Surround The bitstream contains information that was not
encoded in Dolby Surround.
Dolby Surround The bitstream contains information that was encoded
in Dolby Surround. After Dolby Digital decoding, the
bitstream is decoded using Pro Logic.
Not Indicated There is no indication either way.