Every audio packet was delivered as if it were the next 20 ms, duplicates and
late retransmits included. The monitor's capped ring quietly threw the surplus
away, so the speakers sounded fine — but the recorder keeps every sample it is
given, and the file came out longer than the QSO, slowed and stuttering, each
lost-then-resent packet heard twice. trackRxSeq now says whether a packet
advances the stream, and only those are handed on.