summarize the timecode while processing

[dericed]

For instance for the example file at amiaopensource/vrecord#944 (comment)

timecodexml2webvtt 20260116_test_08.timecode.xml > 20260116_test_08.timecode.vtt

should give an stderr output similar to (I only did the 10:34:24;17 to 12:30:00;15 range)

Timecode 1: ATC_LTC (1-Add-101)

Start Timecode	End Timecode	Frames	Duration (s)	Duration
10:34:24;17	10:34:26;17	100	3.334	00:00:03;10
11:59:00;28	11:59:00;29	2	0.066	00:00:00;04
11:59:01;01	12:30:00;15	175	5.834	00:00:05;20

If there's >1 timecode then we could add another summary section. Like

Timecode 1: ATC_LTC (1-Add-101)

Start Timecode	End Timecode	Frames	Duration (s)	Duration
10:34:24;17	10:34:26;17	100	3.334	00:00:03;10
11:59:00;28	11:59:00;29	2	0.066	00:00:00;04
11:59:01;01	12:30:00;15	175	5.834	00:00:05;20

Timecode 2: ATC_VITC (1-Add-102)

Start Timecode	End Timecode	Frames	Duration (s)	Duration
08:34:24;17	08:35:33;21	277	3.334	00:00:09;04

Timecode Relationship:

• Initial offset between ATC_LTC and ATC_VITC is -02:00:00;00
• Final offset between ATC_LTC and ATC_VITC is 08:05:33;06

@iamdamosuzuki thoughts?

[iamdamosuzuki]

This looks good to me.