Generic UDP format

Hello,

I'm currently developing a plugin for SimTools (for motion and dashboard), using the UDP referece coming from this thread: http://assettocorsamods.net/threads/doc-ac-udp-remote-telemetry.60/
I have implemented the handshake succesfully, but I'm now a bit stuck at decoding the UDP payload.
From the above document, I calculated a packet size of 323 bytes. You can check it here, in case I made a mistake: https://docs.google.com/spreadsheets/d/1UTgeE7vbnGIzDz-URRk2eBIPc_LR1vWcZklp7xD9N0Y/edit?usp=sharing

All packets I receive are 328 bytes large. (floats and ints are assumed to be 32 bits, little endian, what about bool ?)
By changing offsets I managed to get a couple of values, but with high uncertainty.
Has there been updates recently on the UDP structure ?
I'm running on PS4.
Thanks for your comments !

 

I didn't realize their was a way to use apps on the console version.

 

Its not been announced but some UDP apps are working on PS4 but not on XBox

https://www.assettocorsa.net/forum/index.php?threads/udp-app-working-with-assetto-on-ps4.43366/

 

You're saying you've implemented handshake successfully... Does it mean you're able to get track and car name ?
If so, I'm very interested if you can try to get also the best time and then we can see how you can push me these 3 infos to my leadearboard https://www.ac-leaderboard.com
It would be awesome to have something similar as RSR for console.

 

Yes, I get succesfully the track name, car name, track config, etc... all those come from the handshake.
What you are mentioning is the RTInfo structure, which I havent tried yet, but I'm confident it is feasible.
The handshake is a bit painfull to integrate in XSim, so I was thinking of having my code acting as a proxy. This would make it possible to push info to your leaderboard easily. Feel free to PM me with details on how to push this info.

 

So I have almost finished the XSim plugin. the UDP payload provides the 3 G forces, which is great. It would be marvellous to get also the yaw / pitch /roll position of the car so the playseat could be moved accordingly, to feel the car position. G forces is essential for kicks, but position are also a must-have. I love to feel going up/down in Spa
If a nice developper could add three floats at the end of the UDP frame, I would be more than happy to implement it.

 

@vthinsel I am using Ruby to read the UDP stream, and some of the datatypes are ambiguous. For example, char is supposed to be 1-byte according to the MS C++ documentation (link), but they're actually 2-byte (wchar_t). Also, the AC UDP doc does not specify text encoding. I think I've figured out that it's UTF-16LE, but the strings are odd. They appear to be terminated by a % character, but there is "junk" after the string. I was expecting some kind of padding. Can you tell me anything about the strings sent by AC?

Also, can you confirm that column C is accurate (in your Google Sheet) for RTCarInfo? That's a very helpful document, btw

My end goal is to write a command line data logger, that connects to AC, and writes JSON records to a file. The schema of the JSON will be defined by passing config files to the CLI tool. I will publish as a Ruby gem once it is complete.

 

Hi !

Yes, strings are indeed a bit strange. I have the feeling the memory is not cleaned. Here is how I extract interesting data :

trackname = System.Text.ASCIIEncoding.Unicode.GetString(UDPBytes.Skip(208).Take(50).ToArray())
trackname = trackname.Substring(0, trackname.IndexOf("%"))

I use '%' as the separator, as you also noticed. It works nicely this way

Y'es, column C should be the one to use.
Here is how I extract data in my code in VB:

SpeedKMH = BitConverter.ToSingle(UDPBytes.Skip(8).Take(4).ToArray, 0)
SpeedMPH = BitConverter.ToSingle(UDPBytes.Skip(12).Take(4).ToArray, 0)
SpeedMS = BitConverter.ToSingle(UDPBytes.Skip(16).Take(4).ToArray, 0)
RPM = BitConverter.ToSingle(UDPBytes.Skip(68).Take(4).ToArray, 0)
Gear = BitConverter.ToInt32(UDPBytes.Skip(76).Take(4).ToArray, 0) - 1
LapTime = BitConverter.ToUInt32(UDPBytes.Skip(40).Take(4).ToArray, 0)
LastLap = BitConverter.ToUInt32(UDPBytes.Skip(44).Take(4).ToArray, 0)
BestLap = BitConverter.ToUInt32(UDPBytes.Skip(48).Take(4).ToArray, 0)
LapCount = BitConverter.ToUInt32(UDPBytes.Skip(52).Take(4).ToArray, 0)
GForceVert = BitConverter.ToSingle(UDPBytes.Skip(28).Take(4).ToArray, 0)
GForceLon = BitConverter.ToSingle(UDPBytes.Skip(36).Take(4).ToArray, 0)
GForceLat = BitConverter.ToSingle(UDPBytes.Skip(32).Take(4).ToArray, 0)
Gas = BitConverter.ToSingle(UDPBytes.Skip(56).Take(4).ToArray, 0)
Brake = BitConverter.ToSingle(UDPBytes.Skip(60).Take(4).ToArray, 0)
Clutch = BitConverter.ToSingle(UDPBytes.Skip(64).Take(4).ToArray, 0)
Steer = BitConverter.ToSingle(UDPBytes.Skip(72).Take(4).ToArray, 0)
PositionNormalized = BitConverter.ToSingle(UDPBytes.Skip(308).Take(4).ToArray, 0)
CarPosition(0) = BitConverter.ToSingle(UDPBytes.Skip(316).Take(4).ToArray, 0)
CarPosition(1) = BitConverter.ToSingle(UDPBytes.Skip(320).Take(4).ToArray, 0)
CarPosition(2) = BitConverter.ToSingle(UDPBytes.Skip(324).Take(4).ToArray, 0)
CarSLope = BitConverter.ToSingle(UDPBytes.Skip(312).Take(4).ToArray, 0)

the char looks to be coded on 4 bytes as well.

Hope it helps !

 

Thank you so much for posting code! It's always helpful to see multiple implementations

I think I'm really close. My Ruby script is able to handle HandshakerResponse and RTICarInfo. I have RTLap defined, but I haven't tested it. I'm not 100% certain it's interpreting the values correctly, but I'm confident my byte offsets are pretty close. I found a great Ruby library that provides a declarative model for binary formats. You can recognize them by the "BinData::Record" inheritance.

I refactored quite a bit and put up a GitHub repo: https://github.com/bradland/ac_telemetry/

- Refactored classes/modules out to /lib
- Made sure output is thread-safe

Right now, it just dumps the output of Ruby's inspect method to STDOUT for each record. Next up is to add an OutputFormatter class that accepts a configuration including field lists and output type (CSV, TSV, etc). I have to figure out how I'm going to merge HandshakerResponse, RTCarInfo, and RTLap to a single stream though. The column sets are very different. It might just be additive (combine fields in to a single set), and include a row type indicator, so I can easily filter/recognize each row when working with the data.

 

Ok this is all a bit of chinees food for me but never the less it would be great to have this tool for PS4/Xbox 1 thanks guy's .
Keep the mustard going

 

Hello ...
It's been along time I didnt race on ACC. I switched to PS5 recently, and fired Xsim stuff.... but nothing came out of ACC.
Is UDP still present in ACC, or is it just in AC ??
Any updates on AC UDP behavior ?

Thanks !

 

Here is what I get when trying to establish the handshake:


firewall not opened on PS5 properly ?