That is, it uses three DMA channels to get the signal out as fast as possible. He has a good overview of the method that you can check out for details, but it goes something like this. The WS2812 ...

In this DMA controller the concept of streams is introduced, where each of the eight streams supports eight channels. This allows for multiple devices to connect to each DMA controller.

The Digital Blocks DB-DMAC-MC-AXI is a Multi-Channel DMA Controller supporting 1 – 16 independent data block / packet / stream transfers. The Direct Memory Access (DMA) Controller IP Core contains 1 - ...

The Multi Channel DMA IP Core for PCI-Express is a powerful PCIe Endpoint with multiple industry standard AXI Interfaces. Up to 16 independent AXI Stream Slaves write DMA Data to the Host. Up to 16 ...