Legacy stereo playback systems will ignore this side-information while players supporting MPEG Surround decoding will output the reconstructed multi-channel audio.
MPEG Surround coding uses our capacity to perceive sound in the 3D and captures that perception in a compact set of parameters.
MPEG Surround uses interchannel differences in level, phase and coherence equivalent to the ILD, ITD and IC parameters.
The reverse-TTT (two-to-three) element generates two downmixed streams, two level differences, one coherence value, and an optional residue signal.
In both the forward (decoding) and reverse (encoding) directions, arranging these filters into a tree setup allows for arbitrary downmixing and recovery.
[19] Due to the relatively small channel bandwidth, the relatively large cost of transmission equipment and transmission licenses and the desire to maximize user choices by providing many programs, the majority of existing or planned digital broadcasting systems cannot provide multichannel sound to the users.
[21] MPEG Surround's backward compatibility and relatively low overhead provides one way to add multichannel sound to DAB without severely reducing audio quality or impacting other services.
Many Internet radios operate with severely constrained transmission bandwidth, such that they can offer only mono or stereo content.
MPEG Surround Coding technology could extend this to a multichannel service while still remaining within the permissible operating range of bitrates.