Downmixing 5.1 surround sound for stereo | Sohonet Help Center
Downmixing 5.1 Surround Sound for Stereo
July 22, 2026
Table of Contents
ClearView Flex supports both stereo and 5.1 surround audio. When a presenter selects 5.1 audio input, all six channels are sent to Apple TV devices, while anyone watching from a browser or another device receives a stereo downmix of that 5.1 audio.
You can now choose which formula ClearView Flex uses to mix 5.1 down to stereo.
Choosing the Downmix Formula
The downmix formula is set per flexbox. Project admins set it in the flexbox’s Default I/O settings. The setting only takes effect when a 5.1 input is used — it has no effect on stereo sources.
There are two options:
- Default — recommended for most workflows. It uses the matrix recommended in RFC 7845 (which defines Ogg encapsulation for the Opus codec, and is also what the WebRTC “multiopus” implementation is based on). Compared with the LtRt or LoRo matrices defined in the ATSC standards, it does not discard the LFE channel and has less impact on the dynamic range of the audio signal.
| L | R | C | LFE | Ls | Rs | |
| L downmix | 0.529067 | 0.0 | 0.374107 | 0.374107 | 0.458186 | 0.264534 |
| R downmix | 0.0 | 0.529067 | 0.374107 | 0.374107 | 0.264534 | 0.458186 |
- LoRo — a Left-only / Right-only downmix that omits the LFE (low-frequency effects) channel. Choose this if your downstream workflow expects a LoRo-style stereo mix, or to match a monitoring or delivery chain that does not use the LFE channel.
| L | R | C | LFE | Ls | Rs | |
| L downmix | 0.414 | 0.0 | 0.293 | 0.0 | 0.293 | 0.0 |
| R downmix | 0.0 | 0.414 | 0.293 | 0.0 | 0.0 | 0.293 |
If you are not sure which to use, leave the setting on Default.
Requirements
5.1 surround sound is only available to users with a Pro subscription or using a Weekly or Monthly Pro credit.