h264 and h265 keyint params settings
See these two links:

1) MeGUI/x264 Settings for an explanation of the parameters like keyint.

2) About --keyint --min-keyint and --scenecut for a discussion at Doom9 about how they interact, specifically


  --keyint is the maximum interval. x264 will insert key frames earlier if it deems them beneficial, e.g. due to a scene change. From my
  experience the majority of key frames are in place because of the
  properties of the video, not because keyint was reached. The larger
  --keyint is the smaller the impact on overall key frame placement should be.