DW Spectrum Media Server allows users to export video using HTTP-GET methods.
In API documentation one can find section called "Direct download" which describes a way to download certain piece of the archive.
Note! The archive piece must exist. I.e. if there's no recording for that time you won't get anything.
Fragment of a camera archive to download is identified by camera id, its start time position and duration. Fragment can be downloaded in mpeg-2/ts (.ts) or Matroska (.mkv) format. No transcoding is performed.
The url to request is:
Note! Here's a link to guide to find camera id.
Example of url:
Note! Fragment piece date and time should be specified according to Media Server Local Time.
"pos" parameter can also take a string containing time in milliseconds since epoch(Unix time).
P.S. One can get list of all existing archive pieces for certain camera with request(identified by duration and start position):