MLSP Minimal Latency Streaming Protocol C library

This library implements custom UDP protocol for streaming frame-like data spanning multiple MTUs. The assumption is that user is only interested in the latest data.

See hardware-video-streaming for other related projects.

Purpose

• minimize latency
• no buffering
• avoid data copies
• multi-frame streaming (e.g. depth + texture)
• private experiments

The only buffering that is allowed is natural arising from sequece:

• we are collecting frame N
• some packet from frame N+1 arrives before frame N is completed
• we may still try to collect frame N until full frame N+1 arrives

Platforms

Unix-like systems (due to network implementation, can be easily made cross-platform).

State

Working proof-of-concept.

Currently whenever packet from frame N+1 arrives, data from frame N is discarded.

Notes:

• library is intended for experiments
• everything is subject to change in the long term
• compatibility is not guaranteed between different commits

Using

Error checking ommited for clarity.

Client:

struct mlsp *streamer;
struct mlsp_config streamer_config= {"127.0.0.1", 9766}; //host, port

streamer=mlsp_init_client(&streamer_config);

while(keep_working)
{
	struct mlsp_frame network_frame = {0};

	//...
	//prepare your data in some way
	//...

	network_frame.data = your_data_pointer;
	network_frame.size = your_data_size;

	mlsp_send(streamer, &frame, 0);
}

mlsp_close(streamer);

Server:

int error;
struct mlsp *streamer;
struct mlsp_config streamer_config= {NULL, 9766, 500}; //listen on any, port, 500 ms timeout

streamer=mlsp_init_server(&streamer_config);

//here we will be getting data
const mlsp_frame *streamer_frame;

while(keep_working)
{
	streamer_frame = mlsp_receive(streamer, &error);

	if(streamer_frame == NULL)
	{
		if(error == MLSP_TIMEOUT)
			continue;
		break; //error
	}
	//...
	//do something with the streamer_frame
	//the ownership remains with library so consume or copy
	//...
}

mlsp_close(streamer);

The same interface works for multi-frame streaming:

• pass number of subframes in mlsp_config
• mlsp_receive returns array of subframes size
• use mlsp_send(m, &frame, 0), mlsp_send(m, &frame, 1), ...

Library uses

Multi-frame streaming client - NHVE Network Hardware Video Encoder
Multi-frame streaming server - NHVD Network Hardware Video Decoder