Audio without video is OK, but WITH video it is delayed I have this audio filterchain (for repetitive short part of the original audio):

[1:a] atrim=start=2.52:end=1:38.0, aloop=100:7700 [audio]


When I used it without video, i. e. in the ffmpeg command I mapped only audio:

-map "[audio]"


then it fulfilled my intent - it started playing immediately (from 0:00)

But when I mapped video, too

-map 0:v -map "[audio]"


then the audio started at 2.52 - the same value as in my atrim filter.

(I tried changing this value and the starting time changed appropriately, too.)

What is the reason for it and how I can fix it?
You've to reset the timestamps:

[1:a]atrim=start=2.52:end=1:38.0,aloop=100:7700,asetpts=N/SR/TB[audio]