[x264-devel] x264 encoding used from ffmpeg takes 2 mins to start

[clime]

Hello,

If I run the command:

$ ffmpeg -f lavfi -i color=c=black:s=1480x910:rate=60 -c:v h264 -f
mpegts "udp://172.22.10.240:5555?pkt_size=1316"

I need to wait around 2 minutes until encoding finally starts, If I
set height to 900 (instead of 910), the encoding starts immediately.
There are 60 cores on the machine and I think this is somehow related
to the problem. Is it possible that there is some thread contention
when frame threading is used?

The problem disappears if I add switch: -tune zerolatency which I
think switches to slice-based threading so the problem is worked
around.

(note: this happens even on the latest ffmpeg build 5.1.1 downloaded
from https://johnvansickle.com/ffmpeg/ so there should be the latest
x264 version)

Thank you very much!
Michal Novotny