6 Functions on the receive (RX) side

26.4493GPPCodec for Enhanced Voice Services (EVS)Comfort Noise Generation (CNG) aspectsRelease 17TS

6.1 EVS primary CNG operation

The CNG operation on the receiver side is depicted in Figure 2. The first bit of the SID payload determines the CNG module. The remaining bits contain the information of the noise generator parameters to render the signal.

Figure 2: Receive side Comfort Noise Generator functions

The RX CNG operation is described in clause 6.7. The synthesis of the LP-CNG is described in sub-clause 6.7.2 and the synthesis of FD-CNG is described in clause 6.7.3 in [2].

6.2 EVS AMR-WB IO CNG operation

The CNG in the EVS AMR-WB interoperable modes use only the LP-CNG decoding scheme for rendering the AMR-WB compatible CN parameters. The complete CNG RX description of the EVS AMR-WB IO mode can be found in [2], clause 6.8.4.