TASK 32·4. A plain MP4 keeps its index (moov) at the end, so a power cut or a killed
process left the entire recording unreadable even though every video byte was on disk.
The record block now carries
`-movflags +frag_keyframe+empty_moov+default_base_moof`: index first, a playable
fragment flushed at every keyframe, so an interrupted take plays to the last fragment.
Record block only — the FLV stream output has no index and never gets the flags.
Rename-on-stop is untouched.
Test: `Args_RecordBlock_IsFragmentedMp4_SoACrashKeepsTheFile` asserts the flags on the
record block and their absence from the streaming block.
Not yet proven on a real interrupted take (kill ffmpeg mid-recording, play the result);
the args test is by construction.
Docs: task-32 slice 4 ticked with that caveat, TASKS row, output.md record note, HANDOFF.
verify.sh: 550 passed (mouse-injection test excluded, desktop in use), 0 warnings.
gramps
e37215d9c4