The data packet’s format and priority.
SDLServiceTypeControl: The lowest level service available.
SDLServiceTypeRPC: Used to send requests, responses, and notifications between an application and a head unit.
SDLServiceTypeAudio: The application can start the audio service to send PCM audio data to the head unit. After the StartService packet is sent and the ACK received, the payload for the Audio Service is only PCM audio data.
SDLServiceTypeVideo: The application can start the video service to send H.264 video data to the head unit. After the StartService packet is sent and the ACK received, the payload for the Video Service is only H.264 video data.
SDLServiceTypeBulkData: Similar to the RPC Service but adds a bulk data field. The payload of a message sent via the Hybrid service consists of a Binary Header, JSON Data, and Bulk Data.
SDLServiceTypeControl = 0x00
case control = 0
SDLServiceTypeRPC NS_SWIFT_NAME(rpc) = 0x07
case rpc = 7
SDLServiceTypeAudio = 0x0A
case audio = 10
SDLServiceTypeVideo = 0x0B
case video = 11
SDLServiceTypeBulkData = 0x0F
case bulkData = 15