Delivery system, delivery method, server device, program, and client device

A client including a CPU (central processing unit) comprising:

• a receiver for receiving content data from a server;
• a controller, implemented by the CPU, that acquires a remaining reproduction time, wherein the remaining reproduction time is a period of time during which a portion of the content data that has not been reproduced can be reproduced, calculates a first correction amount for correcting a bit rate of the content data based on the remaining reproduction time and a target value of the remaining reproduction time, and calculates a second correction amount that is less than the first correction amount when the bit rate is within a correction amount reducing range;
• and
• a transmitter for transmitting a bit rate change request for changing the bit rate based on at least one of the calculated correction amounts to the server, wherein the controller is further configured to:
• narrow the correction amount reducing range as the remaining reproduction time approaches the target value,
• calculate a first bit rate at which the remaining reproduction time matches the target value after a first delay time, and a second bit rate at which the remaining reproduction time matches the target value after a second delay time, wherein the second time delay is longer than the first delay time,
• determine the greater one of the calculated first bit rate and the calculated second bit rate as an upper limit of the correction amount reducing range, and
• determine the smaller one of the first bit rate and the second bit rate as a lower limit of the correction amount reducing range.