A communication terminal, comprising: a receiver configured to receive video data and/or audio data from one or more counterpart communication terminals through a network; an output interface (117, 118) configured to output a plurality of output signals based on the video data and/or audio data being received from the one or more counterpart communication terminals; a processor configured to determine a delay in output of an output signal based on first video data and/or audio data, the first video data and/or audio data being received at the receiver from a first counterpart communication terminal, and generate a first request for changing a code quantity of the first video data and/or audio data being received based on a determination indicating that the delay is detected, the first request including a data ID of the first video data and/or audio data and a reduction coefficient for determining an amount of reduction in the code quantity of the first video data and/or audio data being received; and a transmitter configured to transmit the first request to the first counterpart communication terminal that transmits the first video data and/or audio data, through the network, characterized by the processor further being configured to determine whether a network communication speed of the communication terminal exceeds a first threshold, and a CPU usage rate of the communication terminal, exceeds a second threshold, and determine an output delay factor to be transmission delay when said network communication speed is lower than the first threshold, or internal processing delay when said CPU usage rate exceeds the second threshold, wherein the first request includes the output delay factor. a receiver configured to receive video data and/or audio data from one or more counterpart communication terminals through a network; an output interface (117, 118) configured to output a plurality of output signals based on the video data and/or audio data being received from the one or more counterpart communication terminals; a processor configured to determine a delay in output of an output signal based on first video data and/or audio data, the first video data and/or audio data being received at the receiver from a first counterpart communication terminal, and generate a first request for changing a code quantity of the first video data and/or audio data being received based on a determination indicating that the delay is detected, the first request including a data ID of the first video data and/or audio data and a reduction coefficient for determining an amount of reduction in the code quantity of the first video data and/or audio data being received; and a transmitter configured to transmit the first request to the first counterpart communication terminal that transmits the first video data and/or audio data, through the network, characterized by the processor further being configured to determine whether a network communication speed of the communication terminal exceeds a first threshold, and a CPU usage rate of the communication terminal, exceeds a second threshold, and determine an output delay factor to be transmission delay when said network communication speed is lower than the first threshold, or internal processing delay when said CPU usage rate exceeds the second threshold, wherein the first request includes the output delay factor.