Third measurement, and it names the start-up defect the creator heard as "started off
wrong, then corrected" (ty-20261112-1222-748-0000-2.mp4):
wall clock (audio start -> audio stop) 12.614 s
video: 754 frames 12.588 s correct
audio: 585 packets 12.477 s 137 ms short
pipe connected 160 ms after the session opened
first 150 ms of the audio track digital silence (the mic delay line's head)
The rate is fixed — 12.5 s of show, no accumulating drift — but starting the clock at
connect made the audio stream begin 160 ms after the video stream, so every word sat 160 ms
late and the track came out that much shorter. The silence at the head is the 175 ms mic
delay doing its job, not a fault.
Now the clock runs from session open. Time that passes before ffmpeg connects stays owed,
and it is paid the moment the pipe connects — out of the capture ring, so it is the audio
that was missed rather than padding. Debt larger than one 200 ms chunk continues to be paid
over the following ticks.
674 pass, 0 warnings.
gramps
751d9b199c