DP564 Multichannel Audio Decoder Appendix A: Metadata
A-3
transparent to consumers, certain parameters affect the output of a home decoder, like
when downmixing for a specific speaker configuration, or when the consumer
chooses Dynamic Range Control to avoid disturbing family and neighbors.
Figure A-1 shows a 5.1 + 2 Program Config consisting of a 5.1-channel program and
a two-channel Secondary Audio Program (SAP).
ProgramSource
5.1-Channel
Program
Two-Channel
(Stereo)Program
DP570
MultichannelAudio
Tool
in5.1+2 Program Config
DP571
DolbyE Encoder
in5.1+2 Program Config
Multichannel
MonitorSystem
L/R
C/LFE
Ls/Rs
Lt/Rt
TheDolby E bitstream
containsboth the 5.1- and
two-channelprograms’
encodedaudio, and each
program'smetadata.
TheDolby Digital bitstream
containsa single program’s
encodedaudio and
correspondingmetadata.
DP572
DolbyE Decoder
Metadata
DecodedDolby E bitstream
deliversboth the 5.1- and
two-channelprograms’
encodedaudio along with
correspondingmetadata.
DP569
DolbyDigital Encoder
SAPor Visual
Descriptive
Broadcast
Cable,Satellite,
orTerrestrial
Consumer
Dolby
Two-
Channel
Encoder
Metadata
Figure A-1 Metadata Flow from Production to Consumer
In the simplest terms, there are two functional classifications of metadata:
Informational: These parameters convey information but do not affect either the
encoded bitstream or the decoding process. For example, the Bitstream Mode
parameter describes the audio service provided in the bitstream according to the
ATSC specification. This information may be used by certain components in the
audio system.
Control: These parameters direct how the decoder, encoder, or both process the
audio when certain modes are applied to the encoder or decoder. For example, the
Lowpass Filter parameter determines whether a lowpass filter is applied to the
main inputs of a Dolby Digital encoder, and the Surround Downmix Level
parameter instructs the Dolby Digital decoder how to mix the surround channels
during downmixing.