Enhanced time domain packet loss concealment in switched speech/audio codec

Abstract

This paper describes new time domain techniques for concealing packet loss in the new 3GPP Enhanced Voice Services codec. Enhancements to the existing ACELP concealment methods include guided, improved pitch prediction, increased flexibility and accuracy of pulse resynchronization. Furthermore, the new method of separate linear predictive (LP) filter synthesis aims for sound quality improvement in case of multiple packet loss, especially for noisy signals. Another enhancement consists of a guided LP concealment approach to limit the risk of creating artifacts during recovery. These enhancements are also used in the presented advanced TCX concealment method. Subjective listening tests show that quality is significantly increased with these methods

EVS Channel Aware Mode Robustness to Frame Erasures

“…LSF spectral coefficients are coded with a vector quantizer that takes into account possible lost frames by inserting non-predictive frames at most critical places [11] [12]. Additional information about native EVS packet loss concealment (PLC) can be found in [13] and the EVS standard [14].…”