Notes

Command line tool to decode protocol buffer feed:

protoc --decode_raw  < GTFS-Realtime.protobuf
protoc --decode 'transit_realtime.Shape' gtfs-realtime.proto < GTFS-Realtime.protobuf  
protoc --decode 'transit_realtime.FeedEntity' gtfs-realtime.proto < GTFS-Realtime.protobuf

References