#81 After joining two mpeg files sound and video are not in sync

[Anonymous]

I joined two mpeg1video ( created with ffmpeg -target
vcd -i input.avi output.mpg )
The sound and video are in sync but when i Need to write
it on CD with nero VCD format, sound and video are not
in sync...
First I think it was a mistake of Nero conversions..
But when i Retry it with ffmpeg -i output1.mpg -target
vcd new_output.mpg again we have sound-video sync
problem....
Why can it be ?