Frame counter on Basler cameras cannot be used to detect frame drops

[glopesdev]

We have noticed while debugging alignment issues on Aeon arenas that the Basler cameras do not report gaps in frame counter values when frames are dropped. This seems to be an implementation decision at the driver level, i.e. the counter is possibly a "software" counter rather than a hardware counter.

This means the call to FillGaps in PylonCapture cannot be relied upon to align the frame stream to the trigger timestamp stream in conditions where there may be dropped frames:

aeon_acquisition/src/Aeon.Acquisition/PylonCapture.cs

Line 22 in 9090678

.FillGaps(frame => frame.ChunkData.FrameID, (previous, current) => (int)(current - previous - 1))

To resolve this we would need to instead use the hardware timestamp and compare the delta between subsequent frames and compare it to the expected frame interval, which requires extracting the target FPS from the camera (possibly in the Configure method override). For example:

var frameInterval = 1e9 / Fps; // In nanoseconds. Fps needs to be determined online from camera configuration.

.FillGaps(frame => frame.ChunkData.Timestamp, (previous, current) => (int)Math.Round((current - previous - frameInterval) / frameInterval))

This is currently low-priority since we are not using nor recommending Basler hardware for current and future arenas.