The sACN (streaming ACN) protocol is supported in Artistic Licence ethernet products. The differences between Art-Net and sACN lead to some minor clashes which this document seeks to clarify.
Universe numbering
In Art-Net, universes are called Port-Address and number from 0 to 32,767. There are 32,768 unique numbers.
In sACN, universes number from 1 to 63,999. There are 64,000 unique numbers. The standard reserves the values of 0 and 64,000 to 65,535 for future expansion.
Clearly there is the potential for confusion over the number ‘0’. If a universe is set to ‘0’ and the sACN protocol is selected, Artistic Licence products will use a universe value of ‘1’ instead.
Merging and arbitration
The sACN protocol uses a concept called Component Identifier (CID) as a method to optionally distinguish unique streams of data, and a concept called Priority as a method to define the priority of a stream.
The following table defines how sACN packets A & B are arbitrated or merged when directed to same universe.
| CID | Priority | What happens? |
| A=B | A=B | Streams A and B are identical and are output as DMX. |
| A<>B | A=B | Streams A and B are from different controllers but have same priority. The streams will be merged using the LTP/HTP settings of the product. A maximum of two streams can be merged. If a third stream appears it will be ignored. |
| A=B | A>B | Streams A and B are from the same controller and A has higher priority. B is ignored and A is output. If A stream stops for more than a 5 second time out period, the lower priority stream will take over. If a stream with a higher priority that which is outputting is detected, the higher priority stream immediately takes precedence. |
| A=B | A<B | Streams A and B are from the same controller and B has higher priority. A is ignored and B is output. If A stream stops for more than a 5 second time out period, the lower priority stream will take over. If a stream with a higher priority that which is outputting is detected, the higher priority stream immediately takes precedence. |
| A<>B | A>B | Streams A and B are from different controllers and A has higher priority. B is ignored and A is output. If A stream stops for more than a 5 second time out period, the lower priority stream will take over. If a stream with a higher priority that which is outputting is detected, the higher priority stream immediately takes precedence. |
| A<>B | A<B | Streams A and B are from different controllers and B has higher priority. A is ignored and B is output. If A stream stops for more than a 5 second time out period, the lower priority stream will take over. If a stream with a higher priority that which is outputting is detected, the higher priority stream immediately takes precedence. |