[FFmpeg-user] video to image sequence conversion problem

[BhelPuri]

I'm trying to convert a HD video (1920x1088 H264, 29.97fps) into an image sequence with downsampling (to 5 fps). I used the following:
ffmpeg -i myMovie.mov -r 5 -f image2 foo-%05d.tif

I later process the resulting tif image sequence to track an oscillatory motion. However I'm not sure if the downsampled image sequence is being done right as it seems to be progressively out of sync with the motion. 


I'm not sure how to interpret the output displayed in the format-
frame=  xxx fps=yyy q=0.0 size= 0kB time=ttt bitrate= 0.0kbits/s
where the number yyy varies throughout (0, 7.8 thru 14.0)

Could someone explain why the frames are out of sync and how I should be correcting for that?

Thanks,
SC