steamvr_fix_latency.py

# made by pi (and copilot), available as CC0, no attribution required, use at your own risk, yadda yadda
# requires websocket-client from pip

import websocket
import json
import time
import threading
import re
import sys

# Tweak this value to your liking!
# 8-10 seems to work well for my Vive Pro 1 on 7900XTX
desiredOffset = 8

if len(sys.argv) > 1:
    desiredOffset = int(sys.argv[1])

msgInc = "mailbox_send vrcompositor_mailbox {\"type\": \"vsync_to_photons_increment\"}"
msgDec = "mailbox_send vrcompositor_mailbox {\"type\": \"vsync_to_photons_decrement\"}"

currentOffset = 99999

def on_message(ws, message):
    global currentOffset
    j = json.loads(message)
    msg = j["sMessage"]
    m = re.search('VSyncToPhotonsOffsetMs=([-\d]+)', msg)
    if m:
        currentOffset = int(m.group(1))

def on_open(ws):
    ws.send("console_open")
    # trigger once so we have it in console for sure
    ws.send(msgInc)
    ws.send(msgDec)
    threading.Thread(target=wait_for_result).start()

def wait_for_result():
    global ws
    global currentOffset
    global desiredOffset
    print("Waiting for current offset...")
    time.sleep(1)
    print("Current offset: " + str(currentOffset))
    if currentOffset == 99999:
        print("Error: offset not found")
    else:
        cur = currentOffset
        print("Offset found: " + str(cur))
        print("Adjusting offset by " + str(desiredOffset - cur) + "...")
        while cur > desiredOffset:
            ws.send(msgDec)
            cur -= 1
        while cur < desiredOffset:
            ws.send(msgInc)
            cur += 1
        print("Waiting for confirmation...")
        time.sleep(1)
        print("New offset: " + str(currentOffset) + " (target: " + str(desiredOffset) + ")")
    ws.close()
    print("Done!")

print("Setting vsync_to_photons to " + str(desiredOffset) + "ms")
print("Connecting to SteamVR...")
ws = websocket.WebSocketApp("ws://localhost:27062", on_open=on_open, on_message=on_message)
ws.run_forever()