[FFmpeg-user] Help with concat and overlay

[Joshua Grauman]

Hello all,

I am working on a command that concats two videos from my camera, and then 
overlays another video on top of the concatonated video. It is mostly 
working, but the timing isn't right. For sake of argument, let's say that 
MVI_0001.MOV is 5 min, and MVI_0002.MOV is 3 min (they are broken up by my 
camera, but I just want them together), and overlay.avi is ~8 minutes. I 
want to delay the overlay video 1.1 seconds to align the videos. But when 
I run this command, unless I'm missing something, the first 5 minutes are 
fine, but then the alignment of the overlay is off for the last three 
minutes (it's like it isn't delayed for the last 3 minutes). Does anyone 
see what is wrong with my command?

ffmpeg -i MVI_0001.MOV -i MVI_0002.MOV -ss 1.1 -i overlay.avi -filter_complex "[0:0][0:1][1:0][1:1]concat=n=2:v=1:a=1 [v][a]; [v][2:0]overlay=format=rgb[vout]" -strict -2 -shortest -map [vout] -map [a] out.mp4

Josh