1. A method to be performed on a decoder of a mobile device, the method comprising: decoding, by a dequantizer of the decoder, compressed data to recover high priority data from a received signal, the high priority data being associated with spectral envelope data of spectral information of input data that was previously encoded as the received signal before the received signal was received, the input data corresponding to at least one of speech data, video data, image data, and audio data; and recovering, by a side model of the decoder, low priority data from the received signal, the low priority data being associated with residual spectrum data comprising remaining parts of the spectral information other than the spectral envelope data of the input data, the side model being concurrently trained with the training of a quantizer used to encode the input signal, the quantizer trained with respect to the high priority data.