- Use closed GOP whenever possible.
- Use a fixed Key-Frame Interval of 1/2 GOP length.
- Use few B-Frames when encoding, their decoder is horrible.
- Use few Reference Frames, same reason.
- Use MP4 or MOV, preferably generated with faststart.
- Upscale with Bicubic or Bicublin to 2x or 4x resolution (1080p -> 2160p) if sourcefile is 1080p or lower
- 4:2:0 reduces quality more than expected, just stick with 4:4:4. - No gain for using ProRES, Cineform, or similar large formats - x264 crf=0 is just fine.