Convert RTP data (G729, G711) to Wav.

Further from previous project. Pecap get converted to Wav but at times I have Pcap files where we get RTP data from one side and not the other side. We need to make sure that the WAV file syncs the two sides of conversation. So, for example if we don't get any audio from one side for 9 seconds than the created wav files should not play this side for these 9 seconds. PCAP file contains RTP of a telephone conversation. We need to make sure the final wav created has same audio experience as telephone conversation.