[FFmpeg-user] Output image sequence duplicate first image

[adam smith]

> On 20 Apr 2020, at 16:03, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> Use -vsync 0 and remove -r.

Thanks for your help Carl. 
Adding the -vsync 0 and removing -r did resolve the issue duplicate image output but did not allow me to specify the frequency of the image grabs. 
I will search about for something to allow the frequency to be included. 
Thanks