I just uploaded a video to Facebook yesterday, and then I tried to download the video as HD, and I realized that Facebook actually re-encode the video even though the original video file doesn't rendered with high bitrate or super HD option.
Original video
File size: 50 Mb
Length: ~3 mins
Bitrate: 2 Mbps
Resolution: 1280x720
Frame rate: 25 fps
Reference frame: 8
Level: 4
Audio bitrate: 128 Kbps
Uploaded video
File size: 20 Mb
Length: ~3 mins
Bitrate: 750 Kbps
Resolution: 1280x720
Frame rate: 25 fps
Reference frame: 5
Level: 3.1
Audio bitrate: 48 Kbps
As you can see there's a big loss of quality in the uploaded video. How can I avoid Facebook leave my video untouched? Or it will re-encode the video no matter how small the file size is?