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Metadata Reference

Dolby E and Dolby Digital encoding have many features and options, which are described via metadata.

See also

For a thorough explanation of how the metadata is used, see the separate document Dolby Encoding Guidelines.pdf. The following is a simple explanation of the metadata controls for each audio program (selected by the Metadata Edit Select menu when using the Dolby E configuration).

Program metadata controls

Program

Selects which Dolby E program corresponds to the following metadata controls.

Coding Mode

Selects the channel configuration of the primary audio channels. Does not include the LFE channel.

Data Rate

Selects the data rate of the Dolby Digital data stream. A lower setting uses less space (for example, on a DVD) but lower audio quality; a higher setting uses more space but higher audio quality.

Bitstream Mode

Selects the type of audio being encoded. Complete Main is the most common setting.

Dialog Norm

Selects the level of the dialog in the source material relative to 0 dBFS. Its purpose is to let the decoder adjust playback level so dialog loudness is consistent. When set to −31, a decoder will not change the playback level; when set to 0, the decoder reduces the level by 31 dB.

LFE Enable

Sets whether or not you are encoding an LFE channel.

Center Mix

Selects the gain applied to the center channel when downmixing to stereo. Available only when a center channel is being encoded.

Surround Mix

Selects the gain applied to the rear channels when downmixing to stereo. Available only when rear channels are being encoded.

Dolby Surround Mode

Selects whether a stereo mix has been Dolby Surround encoded, has not, or is unknown. Available only when encoding stereo program material.

Turns a flag on or off indicating whether the audio is copyright protected.

Original

Turns a flag on or off indicating whether the audio being encoded is the original audio or a copy.

Room Type

Selects the type of room used when mixing the audio being encoded.

Mix Level

Selects the audio playback levels used when mixing the audio being encoded.

Info Exists

Turns a flag on or off indicating whether the datastream specifies the Room Type and Mix Level controls.

LoRo Cntr Mix

Selects how the center channel will be downmixed for a normal stereo downmix.

LoRo Surr Mix

Selects how the rear channels will be downmixed for a normal stereo downmix.

LtRt Cntr Mix

Selects how the center channel will be downmixed for a Dolby Surround compatible stereo downmix.

Dolby Surround EX Mode

Selects whether the data stream is indicated to be Dolby Surround EX encoded.

Stereo Downmix Preference

Selects which downmix type is preferred when decoded.

BSI Extension Enable

Enables or disables whether the bitstream info extensions are used in the datastream.

Dynamic Range Compression

Selects the "profile" used to encode a dynamic range compression side-chain signal into the data stream.

Preprocessing controls

Surr 3 dB Attenuation

When ON, the encoder attenuates the rear channels by 3 dB. Necessary for mixes made for cinema that are being encoded for DVD.

Surr Phase Shift

When ON, the encoder applies a 90-degree phase shift to the rear channels. This control should always be enabled unless the material will never be downmixed — otherwise an LtRt downmix might sound unbalanced to the right side.

Lowpass Filter

When ON, the encoder applies a lowpass filter to all audio channels.

LFE Filter

When ON, the encoder applies a lowpass filter to the LFE channel.

DC Filter

When ON, the encoder applies a highpass filter to all audio channels.

Default settings

The metadata controls default to settings recommended by Dolby. You can change the defaults by using Pro Tools' ability to save a user preset and set it as the default. Consult the Pro Tools Plug-Ins User Guide for more information.