TimeSynchronization

[icedream]

• Reveng'ing the protocol
• PoC for protocol implementation
• Drafting API
• Restructuring PoC to conform with drafted API
• Testing

[mhite]

Just poking around @honusz Stagelinq repo and saw this:

https://github.com/honusz/StageLinq/blob/beatinfo/services/TimeSync.ts

Seems to just be a service for getting the uptime of the device?

[honusz]

Just poking around @honusz Stagelinq repo and saw this:

https://github.com/honusz/StageLinq/blob/beatinfo/services/TimeSync.ts

Seems to just be a service for getting the uptime of the device?

Oh, that was some remnant of some test exploring the service. I think I just copied beatinfo module over and was trying to get a response.

I've actually made a bit of progress with it, just haven't pushed the code up to Github.

I've been meaning to do a write-up about where I've gotten to, maybe if I get a chance tmw.

I think the service has something to do with either syncing clocks between devices, or determining latency.
When I push the proper code it will give a better idea. I'm like one step away from having it figured out, so I'm dying to get some input on it.

[mhite]

@honusz - Gotcha. Looking forward to seeing what you've discovered thus far!

[honusz]

@mhite sorry, I haven't forgotten, just been a bit busy.

It seems like the exchange of messages goes something like this:

Device sends a message,
4 bytes - message length
4 bytes - 0x1 (could either be a code for a 'request' or just the number of following 8-byte fields
8 bytes - bigint of the device's clock. Not sure it has any real value, it's just a running clock.

The software (soundswitch or timecode) replies:

4 bytes - message length
4 bytes - 0x2
8 bytes - bigint that the device sent
8 bytes - bigint timestamp that it received the message at (Unix epoch in ms)

That's it really. The software sometimes reverses this by sending a request with its epoch-in-ms time back as the first 8-byte bigint field, and the device responds with the timestamp (using its clock) of when it received the message.

I suppose the simplest utility this has is just letting the players know what latency there is between them.

I need to play around with it a bit more, but I think you can make the clock shift, like, bring the two clocks together. This might be nonsense, and just the result of some mistakes I made in some test replies.
I'm trying to strip down the JS library a bit and make a more performant experimental version, where it'll be a bit easier to experiment with new features and things that require tighter timing.

[mhite]

@honusz - No problem -- this is great information and certainly enough for me to get started poking at this, too! Thank you!