ffmpeg -fflags nobuffer -flags low_delay -reorder_queue_size 0 -i <input> <output>
ffplay -i <input> -fflags nobuffer -flags low_delay -reorder_queue_size 0
NOTE:
fflags nobuffer reduces the latency introduced by optional buffering.
-flags low_delay forces low delay.
-reorder_queue_size 0 sets the number of packets to buffer for handling of reordered packets to 0.