Patent ID: 7813824

Claim:
A transmission signal processing device, comprising: a transmission signal data demultiplexing circuit for receiving transmission signal data in which a video signal and a multi-channel audio signal are multiplexed together and for demultiplexing the received transmission signal data into video signal data and multi-channel audio signal data; a decoder circuit for decoding the multi-channel audio signal data to output a plurality of multi-channel audio signal data including at least front center channel audio signal data and low frequency channel audio signal data; a transmission signal data multiplexing circuit for multiplexing together the video signal data and the front center channel audio signal data to obtain output transmission signal data; a control circuit for controlling the transmission signal data demultiplexing circuit, the decoder circuit and the transmission signal data multiplexing circuit; a volume level control data output circuit for outputting a volume level control data from the control circuit; and a volume adjustment circuit for adjusting a volume level of the multi-channel audio signal based on volume level control data output from the control circuit, the volume adjustment circuit including a multiplier that multiplies each of the plurality of decoded multi-channel audio signal data by a coefficient determined based on the volume level control data to convert each multi-channel audio signal data to multi-channel audio signal data whose volume level has been adjusted, and an attenuator for adjusting a volume level of a multi-channel audio output signal, which is obtained by converting each of the decoded multi-channel audio signal data into an analog signal, in a manner such that the volume level is linked with the coefficient determined based on the volume level control data; wherein the transmission signal data multiplexing circuit at least one of: multiplexes the video signal data with the front center channel audio signal data, to which the low frequency channel audio signal data has been added, to obtain the output transmission signal data, where the volume level of the front center channel audio signal data has been adjusted, and multiplexes the video signal data with the front center channel audio signal data on an input side of the multiplier of the volume adjustment circuit to obtain the output transmission signal data, in which case the volume level control data is output by the volume level control data output circuit.