[georgia]

RF Overmodulation Protection Setting Enabled Disabled

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.

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.

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.

Surround Downmix Level Setting Definition
0.707 (–3 dB) default The Left 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.

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.

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.

Audio Production Information
This parameter indicates whether the mixing level and room type values are valid. If Yes, then a receiver or amplifier could use these values as described below. If No, then the values in these fields are invalid. In practice, only high-end consumer equipment implements these features.

Audio Production Information Setting Definition Yes Mixing Level and Room Type parameters are valid.
No Mixing Level and Room Type parameters are invalid and should be ignored.

Mixing Level
The Mixing Level parameter describes the peak sound pressure level (SPL) used during the final mixing session at the studio or on the dubbing stage. The parameter allows an amplifier to set its volume control such that the SPL in the replay environment matches that of the mixing room. This control operates in dialogue level control, and is best thought of as the final volume setting on the consumer’s equipment. This value can be determined by measuring the SPL of pink noise at studio reference level and then adding the amount of digital headroom above that level. For example, if 85 dB equates to a reference level of –20 dBFS; the mixing level is 85 + 20, or 105 dB.

Mixing Level Setting
80 to 111 dB in 1 dB increments

Room Type
The Room Type parameter describes the equalization used during the final mixing session at the studio or on the dubbing stage. A Large room is a dubbing stage with the industry standard X-curve equalization; a Small room has flat equalization. This parameter allows an amplifier to be set to the same equalization as that heard in the final mixing environment.

Room Type Setting
Not Indicated
Large
Small

Copyright Bit
This parameter indicates whether the encoded Dolby Digital bitstream is copyright protected. It has no effect on Dolby Digital decoders and its purpose is purely to provide information.
Copyright Bit Setting Yes No

Original Bitstream
This parameter indicates whether the encoded Dolby Digital bitstream is the master version or a copy. It has no effect on Dolby Digital decoders and its purpose is purely to provide information.
Original Bitstream Setting Yes No

Note: The parameters DC Filter, Lowpass Filter, LFE Lowpass Filter, Surround 3 dB Attenuation, and Surround Phase Shift appear after the Extended BSI parameters on Dolby E and Dolby Digital equipment menus.

DC Filter
This parameter determines whether a DC-blocking 3 Hz highpass filter is applied to the main input channels of a Dolby Digital encoder prior to encoding. This parameter is not carried to the consumer decoder. It is used to remove DC offsets in the program audio and would only be switched off in exceptional circumstances.

DC Filter Setting Enabled Disabled

Lowpass Filter
This parameter determines whether a lowpass filter is applied to the main input channels of a Dolby Digital encoder prior to encoding. This filter removes high- frequency signals that are not encoded. At the suitable data rates, this filter operates above 20 kHz. In all cases it prevents aliasing on decoding and is normally switched on. This parameter is not passed to the consumer decoder.

Lowpass Filter Setting Enabled Disabled

LFE Lowpass Filter
This parameter determines whether a 120 Hz eighth-order lowpass filter is applied to the LFE channel input of a Dolby Digital encoder prior to encoding. It is ignored if the LFE channel is disabled. This parameter is not sent to the consumer decoder. The filter removes frequencies above 120 Hz that would cause aliasing when decoded. This filter should only be switched off if the audio to be encoded is known to have no signal above 120 Hz.
LFE Lowpass Filter Setting Enabled Disabled

Surround 3 dB Attenuation
The Surround 3 dB Attenuation parameter determines whether the Surround channel(s) are attenuated 3 dB before encoding. The attenuation actually takes place inside the Dolby Digital encoder. It balances the signal levels between theatrical Dolby Laboratories, Inc. Metadata Guide mixing rooms (dubbing stages) and consumer mixing rooms (DVD or TV studios). Consumer mixing rooms are calibrated so that all five main channels are at the same sound pressure level (SPL). To maintain compatibility with older film formats,
theatrical mixing rooms calibrate the SPL of the Surround channels 3 dB lower than the front channels. The consequence is that signal levels on tape are 3 dB louder. Therefore, to convert from a theatrical calibration to a consumer mix, it is necessary to reduce the Surround levels by 3 dB by enabling this parameter.
Surround 3 dB Attenuation Setting Enabled Disabled

Surround Phase Shift
This parameter causes the Dolby Digital encoder to apply a 90-degree phase shift tothe Surround channels. This allows a Dolby Digital decoder to create an Lt/Rt downmix simply. For most material, the phase shift has a minimal impact when the Dolby Digital program is decoded to 5.1 channels, but it provides an Lt/Rt output that can be decoded with Pro Logic to L, C, R, S, if desired. However, for some phase- critical material (such as music) this phase shift is audible when listening in a 5.1- channel format. Likewise, some material downmixes to a satisfactory Lt/Rt signal without needing this phase shift. It is therefore important to balance the needs of the 5.1 mix and the Lt/Rt downmix for each program. The default setting is Enabled.
Surround Phase Shift Setting Enabled Disabled

5.2 Extended Bitstream Information Parameters
In response to requests from content producers, Dolby Laboratories modified the definitions of several metadata parameters from their original definition as described in ATSC document A/52. The revised definitions allow more information to be carried about the audio program and also allow more choices for stereo downmixing. When the metadata parameters carried in Dolby Digital were first described, they were generically called Bitstream Information, or BSI. We refer to the additional parameter definitions as Extended BSI. Because the revised definitions affect metadata parameters that were not used by the consumer decoders, all decoders will be compatible with the revised bitstream. Newer decoders that are programmed to detect and decode the new parameters will be able to implement the new features Extended BSI provides.

Products that allow emulation of the effects of metadata, such as the DP570, normally have a feature that allows emulation of a new (or compliant) decoder or a legacy decoder.

Preferred Stereo Downmix Mode
This parameter allows the producer to select either the Lt/Rt or the Lo/Ro downmix in a consumer decoder that has stereo outputs. Consumer receivers are able to override this selection, but this parameter provides the opportunity for a 5.1-channel soundtrack to play in Lo/Ro mode without user intervention. This is especially useful on music material.

Preferred Stereo Downmix Mode
Setting
Not Indicated
Lt/Rt Preferred
Lo/Ro Preferred

Lt/Rt Center Downmix Level
This parameter indicates the level shift applied to the Center channel when adding to the left and right outputs as a result of downmixing to an Lt/Rt output. Its operation is similar to the center downmix level in the universal metadata.

Lt/Rt Center Downmix Level Setting
1.414 (+3.0 dB)
1.189 (+1.5 dB)
1.000 (0.0 dB)
0.841 (–1.5 dB)
0.707 (–3.0 dB)
0.595 (–4.5 dB)
0.500 (–6.0 dB)
0.000 (–999 dB)

Dolby Laboratories, Inc. Metadata Guide
23
Lt/Rt Surround Downmix Level
This parameter indicates the level shift applied to the Surround channels when downmixing to an Lt/Rt output. Its operation is similar to the surround downmix level in the universal metadata.

Lt/Rt Surround Downmix Level Setting
0.841 (–1.5 dB)
0.707 (–3.0 dB)
0.595 (–4.5 dB)
0.500 (–6.0 dB)
0.000 (–999 dB)

Lo/Ro Center Downmix Level
This parameter indicates the level shift applied to the Center channel when adding to the left and right outputs as a result of downmixing to an Lo/Ro output. When Extended BSI parameters are active, this parameter replaces the Center Downmix Level parameter in the universal parameters.

Lo/Ro Center Downmix Level Setting
1.414 (+3.0 dB)
1.189 (+1.5 dB)
1.000 (0.0 dB)
0.841 (–1.5 dB)
0.707 (–3.0 dB)
0.595 (–4.5 dB)
0.500 (–6.0 dB)
0.000 (–999 dB)

Lo/Ro Surround Downmix Level
This parameter indicates the level shift applied to the Surround channels when downmixing to an Lo/Ro output. When Extended BSI parameters are active, this parameter replaces the Surround Downmix Level parameter in the universal parameters.

Lo/Ro Surround Downmix Level Setting
0.841 (–1.5 dB)
0.707 (–3.0 dB)
0.595 (–4.5 dB)
0.500 (–6.0 dB)
0.000 (–999 dB)

Surround EX Mode
This parameter is used to identify the encoded audio as material encoded in Surround
EX TM
. This parameter is only used if the encoded audio has two Surround channels. An amplifier or receiver with Dolby Digital Surround EX decoding can use this parameter as a flag to switch the decoding on or off automatically. The behavior is similar to that of the Dolby Surround Mode parameter.
Surround EX Mode
Not Indicated
Not Surround EX
Dolby Surround EX

A/D Converter Type
This parameter allows audio that has passed through a particular A/D conversion stage to be marked as such, so that a decoder may apply the complementary D/A process.
A/D Converter Type Setting Standard HDCD