6.1 Mono Signal Low-Band synthesis

26.2903GPPAudio codec processing functionsExtended Adaptive Multi-Rate - Wideband (AMR-WB+) codecRelease 17Transcoding functionsTS

The 0-Fs/4 kHz band of the mono signal is reconstructed by the core ACELP/TCX decoder. In ACELP mode, the decoder is the same as AMR-WB. The TCX mode of the decoder will be described in more details below. Selection between ACELP and TCX decoding in each 256-sample frame is controlled by the mode indicators described in Section 5.2.2 of the encoder. These mode indicators are transmitted as 2 bits in each 256-sample packet.