Use SeekParameters in ClippingMediaSource to snap clipping positions to keyframes

Hello,

I have problem with ExoPlayer - ClippedMediaSource.
In application I have a source video.
From this video, I'd like to play content from start to end - in miliseconds, in sample app its:
start: 1140ms end 3140ms

I'd like to concat it with looped part of a video:
start: 3140ms end 34050ms

Looks like perfect scenario for ClippingMediaSource, LoopingMediaSource and ConcatenatingMediaSource.

I created sample application with code used for it:
https://github.com/bkraszewski/ExoPlayerSample/tree/master

Also you can take a look at video captured:
https://www.youtube.com/watch?v=SOBl6biAUgI

Hoverer I noticed transition between start part and looped part is not smooth, there is a visual glitch when switching part. In docs I found that I need to make sure time match keyframes - but can I make it dynamically?
There is a way to find closest frame to exact moment of video ending so I can adjust clipping time?
This video is just a sample, but our IOS team is using similar logic to stitch videos with same start/end params and its smooth.

Testing ENV:
ExoPlayer 2.9.5 (previously tested with 2.9.4, same result)
Android Studio 3.3
Phone: Samsung S8