Automated Video Transcoding Pipeline for Streaming Platform

Design a robust Bash script that monitors an incoming video directory and automatically transcodes multiple video files using FFmpeg into adaptive bitrate streaming formats (HLS, DASH). The script must handle different input codecs, resize videos for multiple device resolutions (1080p, 720p, 480p), implement parallel processing for efficiency, and generate corresponding manifest files. Include error logging, email notifications for failed transcodes, and a configurable preset system for different content types (movie, short-form, live event).