Shorthair is a portable C++ library uses the Longhair library to provide low-latency loss-recovery, which uses extra bandwidth to make almost any unreliable packet channel suitable for real-time communication.

Erasure codes in software are fast with low-overhead.

Advantages of using erasure codes in online games:

• 50% faster delivery over UDP than over TCP

• 50% less bandwidth used than naive redundancy

• 50% better recovery rate than parity redundancy

Improves the experience for multiplayer mobile apps.

Please take a look at my presentation on Erasure codes for more motivation: Erasure Codes in Software

The shorthair-mobile directory contains an easy-to-import set of C code that also builds properly for mobile devices and Windows-based computers.

This library is only available in C++ code, which you can wrap for your favorite language.

Your C++ code should have a class instance that derives from IShorthair and implements its interface:

	// Called with the latest data packet from remote host
	virtual void OnPacket(u8 *packet, int bytes);

	// Called with the latest OOB packet from remote host
	virtual void OnOOB(u8 *packet, int bytes);

	// Send raw data to remote host over UDP socket
	virtual void SendData(u8 *buffer, int bytes);

It is safe to call Send and SendOOB from any thread.

The same thread that calls Recv should also be calling Tick.

• Uses fastest, smallest Reed-Solomon codec available (Longhair).
• Full-duplex communication over a lossy channel.
• Adds a dial to control packet loss to any acceptable rate for applications over UDP.
• Calculates and generates precisely the amount of redundancy required to achieve the target loss rate.
• It supports variable-length data packets.
• Overhead is 5 bytes/packet.
• Does not require multiple threads.
• Library has a clean platform-independent interface with minimal configuration required.

This software was written entirely by myself ( Christopher A. Taylor [email protected] ). If you find it useful and would like to buy me a coffee, consider tipping.