ffmpeg: Execute command in while loop [duplicate]

I'm trying to execute a ffmpeg command on a list of video files, stored in an ascii file.

I simply tried to combine the reading of filenames with a while loop but it seems not to work. For some reason every video filename gets cropped

while read p; do 
    ffmpeg -i "$p" [some options] ;
done < filelist.txt

Any idea why this is happening?

filelist.txt looks like this:

video1.mp4
video2.mp4
video3.mp4
[...]