Wrong handling of absolute time stamp when time zone is specified

[SebastianProg]

Python version

3.10.14 | packaged by conda-forge | (main, Mar 20 2024, 12:40:08) [MSC v.1938 64 bit (AMD64)]

Platform information

Windows-10-10.0.22631-SP0

Numpy version

1.26.4

mdfreader version

4.2

Description

When reading MDF files version 4.1 with specified timezone the fileMetadata item 'time' is wrong. Only contains the offset but not the real timestamp. This is because of lines 1341 - 1343 in mdf4reader.py, which not includes the timestamp value of line 1340. Maybe these lines need to be as comment if there is no correct handling of offset items, see attached screenshot:

Information about the file content is shown in next screenshot:

[ratal]

Hi,
Indeed Local time = UTC time + time zone offset + DST offset.
so it should be ttime += info['HD']['hd_tz_offset_min'] * 60 + info['HD']['hd_dst_offset_min'] * 60
adding to hd_start_time probably is missing. Could you propose a pull request after trial ?

[SebastianProg]

Hi,
thanks for the reply.
When I tried this, the challenge will be that the parsed timestamp will be interpreted as Unix Timestamp as this is based on UTC time so when converting the parsed timestamp in Python to datetime it will apply the time offset again and the final time will be wrong again.
Any suggestions how to handle it in a robust way?

[SebastianProg]

I can think of two solutions:

1. Providing the raw information in metadata block (timestamp, timezone and daylight saving time separately) and the user is responible to handle it. Probably the most compatible solution to the current version.

2. Providing a real date-time information (conversion of timestamp and timezone information to datetime when parsing the file) in metadata block. This would be great but maybe not compatible with earlier implementation and usage.

What will be preferred or do you see another solution?