Transmission device, method for controlling transmission device, control program, and recording medium

A server (2) is provided with: an index information generation unit (24) which generates index information (28) for switching content to be played back in sub-segment data when a plurality of segment data (27) has been encoded to predetermined sub-segment data; and an encoder (23) which makes a client (1) acquire the index information (28) generated by the index information generation unit (24).