Abstract: According to one embodiment, a sound playback apparatus includes receiving mechanism for obtaining a sound packet including sound data about outputs of a predetermined number of channels, downmix information receiving mechanism for obtaining downmix coefficient information, control mechanism for determining whether downmix processing is to be performed for the sound packet by using the downmix coefficient information or not, sound processing mechanism for performing downmix processing of the sound packet based on the downmix coefficient information when the control mechanism determines to perform downmix processing for the sound packet, and sound output mechanism for outputting the sound data downmixed by the sound processing mechanism to a speaker connection terminal.