[FFmpeg-user] Understanding/preventing buffer overruns

[Simon Roberts]

Hi all, I have a recording configuration going that's grabbing three
1080 30p inputs and one 720 30p input simultaneously, and seems to be
capable of either prores or libx264 crf 23 compressions. The resulting
video appears to be smooth, and when I include a clock in one of the
streams, it maintains good time over a couple of minutes of test.

But... I get almost continuous buffer overruns after about a minute.
Can someone tell me where to start learning about how I might fix this
(I presume it can't be good that it's doing this even though the
output seems to be OK, right?)

One negative thing I notice is that when I play this back with VLC it
complains about timestamps (and some other complaints about recursion
and decoder hardware that I don't think are related to this)

[00007fc4251af680] main decoder error: Could not convert timestamp
4637816048 for FFmpeg
[00007fc425099d20] main decoder error: Timestamp conversion failed
(delay 1000000, buffering 100000, bound 9000000)
[00007fc425099d20] main decoder error: Could not convert timestamp
4637849382 for FFmpeg
[00007fc4251a19f0] main decoder error: Timestamp conversion failed
(delay 1000000, buffering 100000, bound 9000000)

these repeat extensively

Here's a sample of the messages during recording (which also repeat
essentially continuously)

[decklink @ 0x55b2249e8580] Decklink input buffer overrun!
    Last message repeated 1 times
[decklink @ 0x55b2249a4040] Decklink input buffer overrun!944kB
time=00:00:52.30 bitrate=549308.8kbits/s dup=35 drop=4048 speed=0.999x
[decklink @ 0x55b2249e8580] Decklink input buffer overrun!
    Last message repeated 13 times

Can anyone point me at what part of the documentation might address
this, or better still give me hints?

TIA,
Simon