5.7.5.2 Synchronization Short Packet Demux
Short packets include Frame Synchronization packets and Line Synchronization packets. Each image must begin with a Frame Start (FS) packet containing the Frame Start Code, and must end with a Frame End (FE) packet containing the Frame End code.
| Packet | Data Type | Handler |
|---|---|---|
| Synchronization Short Packet (SSP) | Frame Start Code | Per Virtual Channel Interrupt |
| Frame End Code | Per Virtual Channel Interrupt | |
| Line Start Code (optional) | Per Virtual Channel Interrupt | |
| Line End Code (optional) | Per Virtual Channel Interrupt | |
| Reserved | SSP Error Interrupt reserved |
The 16-bit frame number can be retrieved in the CSI2DC user interface. The Short Packet Data field indicates the frame number or the line number depending on the configuration. The behavior of the 16-bit frame number must be one of the following:
- Frame number is always 0, meaning that the frame number is inoperative.
- Frame number increments by 1 for every FS packet received with the same virtual channel identifier and is periodically reset to one, e.g. 1, 2, 1, 2, 1, 2 or 1, 2, 3, 4, 1, 2, 3, 4.
- The Frame number must be a non-value.
The behavior of the 16-bit line number must be one of the following:
- Line number is always zero — line number is inoperative.
- Line number increments by one for every Line Start (LS) packet received within the same virtual channel and the same data type. The line number is periodically reset to one for the first LS packet after a FS packet. The intended usage is for progressive scan.
- Line number increments by same arbitrary step value greater than one for every LS packet with the same virtual channel and the same data type. The line number is periodically reset to a non-zero arbitrary start value for the first LS after an FS packet. The arbitrary start value may be different between successive frames. The intended usage is for interlaced video data.