Processing fps for files - deepstream -app

I ran two videos each having 10 fps for inference with the default deepstream reference app. I found out that the files are processed at much higher fps than 10 fps. I am doing some tests and I need the pipeline speed to never exceed the video speed and even if t exceeds it should not be by much - < 13fps.
How to achieve this? Also, why the perf measure gives the fps way higher than 10 fps.

not sure if you set sync=1 sink group of config file, could you try it if not. Pls share your config if that cannot work.
Also may I know how did you measure the fps?