File packetContainer.h
↰ Parent directory (include/libcaer/events)
Definition (include/libcaer/events/packetContainer.h)
Detailed Description
EventPacketContainer format definition and handling functions. An EventPacketContainer is a logical construct that contains packets of events (EventPackets) of different event types, with the aim of keeping related events of differing types, such as DVS and IMU data, together. Such a relation is usually based on time intervals, trying to keep groups of event happening in a certain time-slice together. This time-order is based on the main time-stamp of an event, the one whose offset is referenced in the event packet header and that is used by the caerGenericEvent*() functions. It’s guaranteed that all conforming input modules keep to this rule, generating containers that include all events from all types within the given time-slice. The smallest and largest timestamps are tracked at the packet container level as a convenience, to avoid having to examine all packets for this often useful piece of information. All integers are in their native host format, as this is a purely internal, in-memory data structure, never meant for exchange between different systems (and different endianness).
== Packet Containers and Input Modules == The “packeting system” works in this way: events are accumulated by type in a packet, and that packet is part of a packet container, by an input module. The packet container is then sent out for processing when either the configured time limit or the size limit are hit. The time limit is always active, in microseconds, and basically tells you the time-span an event packet covers. This enables regular, constant delivery of packets, that cover a period of time. The size limit is an addon to prevent packets to grow to immense sizes (like if the time limit is high and there is lots of activity). As soon as a packet hits the number of events in the size limit, it is sent out. The regular time limit is not reset in this case. This size limit can be disabled by setting it to 0. The cAER DVS128/DAVIS/File/Network input modules call these two configuration variables “PacketContainerInterval” and “PacketContainerMaxPacketSize”. Too small packet sizes or intervals simply mean more packets, which may negatively affect performance. It’s usually a good idea to set the size to something around 4-8K, and the time to a good value based on the application you’re building, so if you need ms-reaction-time, you probably want to set it to 1000µs, so that you do get new data every ms. If on the other hand you’re looking at a static scene and just want to detect that something is passing by once every while, a higher number like 100ms might also be perfectly appropriate.
Includes
common.h(File common.h)