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SLOTTED UDP

This repository contains exploratory code to examine the possibilities of streaming time sensitive data, such as media, over a LAN using UDP/IP multicast.

If successful, slotted udp can be used as a foundation to implement a lightweight, hardware independent replacement for OpenAVB.

Currently the code is just an API skeleton that wraps stock multicast. As we move forward we will implement clocking, skew detection and additional features to flesh out the implementation behind the API.

QUICK START

$ make

[Terminal 1 (Receiver)]
$ ./slotted_udp_test -r -

[Terminal 2 (Receiver)]
$ ./slotted_udp_test -r -

[Terminal 3 (Sender)]
$ ./slotted_udp_test -s -
Hello world.
<ctrl-d>

Usage

slotted_udp_test -s [file_name] | -r [file_name]  [-S slot]
  -S slot          Attach to the given slot (1-%d). Default 1
  -s [file_name]   Send file_name over the given slot.
                   Use '-' to stream from stdin. End with ctrl-d.
  -r [file_name]   Receive data from sender and write to file_name.
                   Use '-' to stream to stdout.

TODO

• Command line arguments for port and address
• Command line argument for slot count
• Command line argument for max packet size
• TDMA slotting for sender

UDP/IP PACKET FORMAT

Byte	Name	Type	Description
0-3	slot	uint32_t	Slot that the packet was sent in
4-11	transaction_id	uint64_t	Incremental transaction ID
12-19	clock	uint64_t	Monotonic clock of sender, in usec
20-...	data	opaque	Data.

The length of data is determined by subtracting 20 from the total length (header size) of the UDP/IP packet ereceived.