[FEATURE] Cross-video analytics output into a single summary csv

[mattdawkins]

Add the ability to select multiple videos/image sequences in a folder and get one output csv with the following properties:

1. Max-N count in the first X minutes of a sequence above threshold (for every object type report the frame with max occurrence and it's timestamp)
   or
2. Mean count for the first X minutes of a sequence above threshold (average count / frame of every known type)

[subdavis]

Please provide an exact CSV schema or format.

[mattdawkins]

VIAME has a csv format in https://github.com/VIAME/VIAME/tree/master/examples/archive_summarization

but it's not exactly a standard, its header looks like: # video/sequence_id, time_id, frame_id, detection_count

For reporting these max-n counts, with 1 line per video but any format is really fine as long as it contains the requisite info