Fuchs, G.G.FuchsHelmrich, C.R.C.R.HelmrichMarkovic, G.G.MarkovicNeusinger, M.M.NeusingerRavelli, E.E.RavelliMoriya, T.T.Moriya2022-03-132022-03-132015https://publica.fraunhofer.de/handle/publica/39172310.1109/ICASSP.2015.71790682-s2.0-84946037564Speech coders operating in time domain can be extended with a frequency domain mode to improve encoding of music, even though this is challenging at low delay. In such a scenario, the short analysis window limits the benefit of the transform coder, while a delayless switch between the two coders constrains the system further. The paper presents an LPC and MDCT-based audio coder part of the new 3GPP codec for Enhanced Voice Services, which aims to solve the issues. Several advanced coding tools are introduced to alleviate the constraints: transient handling is improved, harmonic structures are better preserved, and the modeling of the zero-quantized frequencies is enhanced. Test results show that the obtained low-delay switched coder brings a clear improvement over a speech coder and is competitive even in comparison to audio coders with higher delay.enconference paper