NVVE_SLICE_COUNT is ignored in encoder if set to more than 4

According to the documentation of the NVIDIA H.264 encoder, you can set the NVVE_SLICE_COUNT parameter to the number of slices you want to get.

This parameter is used if you set this value to something less than or equal to 4. For example, you can set it to 3 and you will get 3 slices in the output.

But if you set it to more than 4, this parameter is ignored and you get only 4 output slices.

In my cases, I wanted to specify that each row is in a different slice, to make it more likely the output slice can be packetized in one RTP packet that would fit into a network packet.

The documentation doesn’t say 4 is the maximum number of slices. Is this maximum number hardcoded?