This protocol was created by adsb-tools. This specification is official.
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.
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
See definition file for details.
To decode a stream file:
$ protoc-c --proto_path=adsb-tools/proto --decode=AdsbStream adsb-tools/proto/adsb.proto < streamfile