[FFmpeg-user] fps not working as expected

[Henry Wagner]

Hi,

I am using ffmpeg to assemble a series of 900 frames into a mp4 video, with
these parameters:

ffmpeg -i frames%03d.png -vcodec libx264 -b 5000k -sameq -s hd720 -r 30
video.mp4

With 900 frames and a frame rate of 30 (-r 30) I am expecting a 30 second
video, but the video is 35 seconds. Is there a way to force the video to be
exactly 30 fps and 30 seconds?

Thanks,
Henry