There are two different packet types of MIPI CSI-2, long and short packets. Short packets use a 32-bit frame structure and are commonly used for signaling frame start, frame end, or other synchronization information from the source. Long packets have a variable byte count based on the format of the data to be transmitted and are typically used to transmit a single video line. In each long and short packet, there is a header which stores information about the type of packet (data ID) and which virtual channel (VC) source the information came from.

One typical video frame transmitted via CSI-2 can be broken down into the following items.

• Frame start – 32-bit short packet
• Low-Power State (LPS)
• The 1^st line of valid video data – Long packet, which is further divided into:
  • 32-bit packet header (packet header)
  • Valid data, for example, for RAW12, two pixels have 24 bits
  • 16-bit packet footer (packet footer)
• Low-Power State (LPS)
• The 2^nd line of valid video data
• Low-Power State (LPS)
• The 3^rd line of valid video data
• …
• Frame end – 32-bit short packets