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adsb-tools/protocols/proto.md
Ian Gulliver 0b2a8469ce Formatting
2016-02-28 20:05:40 -08:00

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Protobuf protocol

This protocol was created by adsb-tools. This specification is official.

Format

Protocol buffer encoding. Proto definition is here. Stream is a series of Adsb records with length encoded in a prefix (protobuf isn't self delimiting). The prefix is structured such that an entire stream is a valid AdsbStream record.

First frame must always be an AdsbHeader; frames can otherwise appear in any order, including additional headers.

Prefix

  • 0x0a: in protobuf encoding, field #1, type 2 (length-encoded bytes); (1 << 3) | 2
  • Length of packet not including prefix, encoded as a base 128 varint

Packet

See definition file for details.

Tips

To decode a stream file:

$ protoc-c --proto_path=adsb-tools/proto --decode=AdsbStream adsb-tools/proto/adsb.proto < streamfile