Sound packet reproducing method, sound packet reproducing apparatus, sound packet reproducing program, and recording medium

A reproducing apparatus for audio packets which receives a stream of sent audio packets containing an audio code generated by encoding an input audio data stream frame by frame and reproduces an audio signal, comprising:

• a packet receiving part which receives audio packets from a packet communication network;
• a receiving buffer for temporarily storing the received packets and reading out packets in response to a request;
• a state detecting part which detects the largest delay jitter and the number of buffered packets, the largest jitter being any of the largest value and statistical value of jitter obtained by observing arrival jitter of the received packets over a given period of time and the number of buffered packets being the number of packets stored in the receiving buffer;
• a control part which obtains based on the largest delay jitter an optimum number of buffered packets by using a predetermined relation between the largest delay jitter and the optimum number of buffered packets, the optimum number of buffered packets being the optimum number of packets to be stored in the receiving buffer, determines, on a scale of a plurality of levels, the difference between the detected number of buffered packets and the optimum number of buffered packets, and generates a control signal for instructing to perform any of expansion, reduction, and preservation of a waveform of the decoded audio data stream in accordance with a rule to make the number of buffered packets close to the optimum number of buffered packets, the rule being established for each level of the difference;
• an audio packet decoding part which decodes an audio code in a packet corresponding to the current frame extracted from the receiving buffer to obtain a decoded audio data stream in the current frame;
• and
• a consumption adjusting part which performs any of expansion, reduction, and preservation of the waveform of the decoded audio data stream in accordance with the control signal and outputs the result as sound data of the current frame.