# Ubuntu/Debian sudo apt install x265 # macOS with Homebrew brew install x265 # Windows: Use ffmpeg full build with GPL Cause: Variable Frame Rate (VFR) source vs. Constant Frame Rate (CFR) preset requirement. Fix: Force CFR and resample audio:
ls *.mov | parallel -j 4 'ffmpeg -i {} -c:v libx265 ... ._sone183.mp4' If the 1.83 Mbps target is strict, replace CRF with two-pass:
-b:v 1830k # 1.83 Mbps Symptom: MP4 plays locally but requires full download before playing in a browser. Fix: Remux with qt-faststart or re-encode with -movflags +faststart . If using a pipe or streaming output, omit the flag. 4.5 Permission Denied on Output Directory Automated "work" jobs often run under system accounts. Ensure the destination folder has write permissions: