Support for reading and using timestamps from Stream2 #77
Description
Eiger's Stream2 sends precise timestamp info along with frame data. Specifically, the fields below are available in an "Image Message". The texts in quotes comes from the SIMPLON v1.8 API Reference document.
series_date: "Date and time of the start of the series". Sent as a string in the RFC3339 formatstart_time: "Start time of the image in seconds, relative to series_date. The denominator is the time base frequency which is constant for the duration of the series.". Here the docs are not very clear. In practice (as observed in a real detector)start_timeis sent as a CBOR rational number, where the numerator is the number of 'ticks' of a clock while the denominator is the clock frequency. Multiplying the two together results in the time offset sinceseries_date, in seconds.
We can make use of both fields above to derive the precise timestamp of a frame, and then conditionally set that as the timestamp of the corresponding NDArray.