Table of Contents

Standard Configurations

Standard configurations are all the typical configurations, such as stereo and 5.1, where each channel has a name giving a hint about the placement of its corresponding speaker. For example, "Height Back Left" is placed to the back and to the left of the listener, above the ground.

LFE

The LFE (.1) is never downmixed. If both the input and output configurations have an LFE channel, the signal of the LFE channel of the input is copied over to that of the output. If the output does not have an LFE channel, the signal of the LFE channel of the input is dropped.

Surround versus side

With 4.x and 5.x configurations, there is only one pair of speakers that is not in the front, so there is no distinction between "side" or "back" channels. They are both synonyms of "surround." For these configurations, we chose to consistently call surround channels SL and SR, where "S" stands for "surround." This led to a somewhat arbitrary decision whereby the surround channels SL and SR of 4.x and 5.x configurations are mapped to the side channels SL and SR of 6.x and 7.x configurations, instead of the back channels BL and BR. This preference is justified by the fact that the preferred angles of surround speakers in 5.1 setups, as advocated by Dolby, matches those of the side speakers in 7.1 setups.

For more details, please see http://www.dolby.com/us/en/guide/surround-sound-speaker-setup/5-1-setup.html and http://www.dolby.com/us/en/guide/surround-sound-speaker-setup/7-1-setup.html .

[Note] Note
At the moment, there is no way to configure Wwise to route surround channels of 4.x or 5.x configurations into the back channels of 6.x or 7.x configurations.

Normalization

The Wwise downmix performs no normalization, given the arbitrary nature of normalization coefficients. It is, therefore, common that downmixing from configurations with large numbers of channels to configurations with few channels results in loudness gains. Designers should take care of normalizing according to their taste using States or RTPCs on Bus volume(s).

Configurations with height channels

At the moment, downmix tables for configurations with "height channels" (HXX) do not exist. Height channels are treated like the LFE channels. This means they are mapped directly when they exist in the output but, otherwise, they are dropped.

For example, here is what happens if you route a 7.0.4 input (FL-FR-C-SL-SR-BL-BR-HFL-HFR-HBL-HBR) to a 5.0.2 output (FL-FR-C-SL-SR-HFL-HFR):

  • The input's BL and BR are downmixed into the output's SL and SR, as per the equations of the To 5.x table.
  • The input's HFL and HFR are passed to the output's HFL and HFR.
  • The input's HBL and HBR are dropped because they do not exist in the output.

Other configuration types

Anonymous and ambisonic configurations do not implement downmixing. Routing behaves like the LFE channel in standard configurations. If a corresponding channel exists in the output, it is copied over; otherwise, it is dropped.