It varies… We have several configuration options to optimize storage on our mDVRs. H264 is the video codec that we use which is really good for file size optimization.   As far as how many hours can stored, it depends how big the storage drive is in gigabytes, the video resolution, and how many cameras are recording simultaneously per vehicle.   Example: Our cameras can record up to 1080p (Full HD) up to 24fps. At that resolution and frame rate, it would eat through the storage pretty quickly, especially for vehicles that have multiple cameras. Most customers opt for 720p (standard HD) at around 15fps. At this configuration, you will still have smooth and clear picture.