- A recording killed mid-way had wrong timestamps in players: its fragmented MP4's header gives a
length of 0, and one cut short never gets the index a clean stop writes. modules/Screen_Record's
record_remux now copies every recording's packets, as they are, into a regular MP4 (one header
first with the length and every frame's index; faststart) before it goes into the library;
should that fail, the fragmented MP4 goes in as it was.
- Keyframes were every 60 frames, which, with frames written only on change, could span minutes
of time, and a crash could lose a fragment that long. One is now forced every 2 s of time
(forced-idr for NVENC and libx264).
- A crash's leftover no longer claims a region at 0, 0 in its capture.json.
- record-probe -remux IN OUT. Tests: a recording cut at its last fragment, as a crash cuts it,
goes in as a regular MP4 of the time before the cut.
- Checked on the recording that showed it: its MP4, cut mid-fragment, rewrites to 76 frames
(5.2 s) with positive frame durations. A 12 s still recording now fragments every ~2 s, and
the app killed 10 s into a recording leaves 8.1 s.
