The constant current chip is the WS2811. The chip itself has two speeds, 400KHz or 800KHz. the WS2812 runs at 400KHz and the WS2812B runs at 800KHz.
Communication to these devices is via a daisy chain with a NRZ type wave form. Each chip has 3 channels with 8 bit PWM.
So, at 800KHz to send a 1 bit you send a high pulse of duration 0.8uS and the a low of 0.45uS.
To send a 0 bit you send a high pulse of durations 0.4uS and then a low of 0.85uS.
Total bit lenght is 1.25uS ±300nS
The timing tolerances are ±150nS