counterJumps

Normal-mode packets the cursor could not follow: one only partly behind lastSample (its samples are appended at the running cursor), a jump further than the decoder fills (PacketCodec.MAX_FILLED_GAP_SECONDS; the cursor then resyncs to the wire without dummies), and a counter that moved back and stayed there (the cursor resyncs to it; see stalePackets). Each is a gap lastSample cannot account for, so it is counted here instead of in the dummy stream.