Why set nano_sleep_packet_s.tv_nsec to 665778 ns?

I can use sendts to send ts files over udp successfully now.
However, I am confused about one variable in line 774 of sendts.c as below.
`nano_sleep_packet_s.tv_nsec = 665778; // 1 packet at 100Mbps`
Can anyone teach me how did this value "665778" come from? 

