Proposed design constraints for noise suppression, DTX, and non-speech inputs
The source proposes to update Table 6.2-1 in draft TR 26.940 as follows:
[The proposal consists of updating Table 6.2-1 with the following design constraint parameters:]
Parameter: Potential use of noise suppression as part of the codec
Design Constraint: If noise suppression is supported as part of the candidate codec, it can be disabled to preserve background signals
Editor's note 1: Requirement to disable noise suppression may be considered in connection with specific operating bit rate(s)
Editor's note 2: Solution behaviour w.r.t. potential noise suppression is primarily enforced via performance requirements. The default operation for tests is with noise suppression disabled.
Parameter: Discontinuous transmission including voice activity detection and comfort noise
Design Constraint: The candidate codec shall provide a framework for voice activity detection (VAD) and discontinuous transmission (DTX) with comfort noise generation (CNG). It shall be possible to operate the codec with DTX on or DTX off.
Editor's note: Operation relating to DTX on and disabling/enabling potential noise suppressor may need to be clarified
Parameter: Robustness to non-speech input
Design Constraint: The candidate codec shall be robust to noisy speech (stationary noise 5-15 dB, non-stationary noise 10-25 dB), background signals during and between speech segments, and other non-speech input signals
Editor's note 1: May need to be in performance requirements
Editor's note 2: Relevant background signals, etc. to be further defined as part of performance requirements, these include both stationary and non-stationary background signal types