Avalon ST custom IP component

Yes, you'll not want to change the control packets. The first 4 bits of a packet (these are the lowest 4 bits in your data width, so if you're using 24 bits the first 24-bit word will have the code in bits 3-0 and 23-4 are not used) will have a code that shows whether it's a control packet or not. If the first 4 bits are 0 then it's a video packet, if it's 15 then it's a control packet. 1-8 are reserved for custom user packets, 9-12 for Altera future use, 13 = Ancillary data, 14 reserved for Altera future use.

0 and 15 are definitely correct. The text suggests 7 user packets and 5 future Altera packets, so there is some ambiguity about the others. My guess is 8 is wrong as a user packet.

I should add that it's all on page 2-10 of the ug_vip.pdf guide.