How GT7 telemetry works on PS5: inside ApexTrace

Gran Turismo 7 telemetry consists of numerical data about the car and the driving session that an application can receive from PS5 over a local network. ApexTrace processes these data, saves laps and turns the recording into charts for analysis on a Windows PC.

A lap time shows the result, but not what happened along the way. Inspecting braking, corner speed and throttle application requires a chain from individual network messages to a usable recording. Here is how that chain works in ApexTrace.

What Gran Turismo 7 sends

PS5 transmits telemetry in small network messages called UDP packets. They contain speed, engine RPM, pedal inputs, gear, car coordinates and other parameters. The available fields depend on the packet format.

Charts use these numerical values. The application does not need to read instruments from an image or analyse race video to produce them.

Turning packets into readable values

A packet is not a table with labelled columns. The ApexTrace decoder decrypts supported packets, checks their structure and extracts values from the corresponding fields.

It then converts data to readable units, such as pedal percentages and kilometres per hour. Validity checks help reject values that cannot safely be used downstream.

Recorded values and calculated measures

Some parameters come directly from GT7. ApexTrace calculates others from them: successive coordinates can reconstruct the driven line and estimate distance travelled.

That distinction matters. A recorded trajectory represents the car's movement; it does not by itself describe the edges of the asphalt or the kerbs. Calculated measures need to be read in the context of their inputs.

Building a lap archive

One packet describes a moment. ApexTrace associates a sequence of states with a lap and session, updates live readings and saves recordings in a local archive.

Storage uses SQLite, a database on the computer that needs no separate server. Saved sessions remain available later without the PS5 or an active race.

Why lap comparison follows distance

Two laps may reach the same corner at different times after the start. Aligning them only by stopwatch time can compare different parts of the track.

For A/B comparison, ApexTrace therefore aligns progress along the distance. Speed, brake and throttle can be inspected at corresponding sections, while the delta chart shows the changing time difference. The user selects both laps; neither has to be the fastest.

Behind the ApexTrace window

The desktop shell uses Tauri. It starts a local telemetry processing service implemented in Python, and the interface displays the prepared data.

This separates packet reception, session storage and chart presentation. The packaged Windows application starts its required components itself; users do not need to install Python separately.

From a chart to an observation

Telemetry turns “that corner felt different” into something specific: a different braking point, speed or return to throttle.

A chart does not establish the cause automatically. Car, tyres, conditions and driver inputs all matter. A difference is a hypothesis to test on another run, not a promise of a faster lap.