I spent 24 hours exporting a 1920x1080 video at a really high bitrate. I need to make another copy to upload to vimeo at a slower bitrate because the file size is too big. I was wondering if it is safe to re-compress the already exported file at a slower bitrate without much loss in quality.
Original Export - h.264, 30fps, 1920x1080, 50mbps
Second Export - h.264, 30fps, 1920x1080, 10mbps
It saves me almost 23 hours in exporting time if I can export the already exported file...just wondering what will I be losing?
There will be some loss. Whether it's acceptable is subjective.
You may be making a fundamental mistake in your workflow though. You should read the sticky at the top of the forum on how to get the fastest compression help.
The problem may be that it took you 24 hours to do the encode. Re-encoding the encoded file may also take you a long time. You may lose quality and save no time. If you want detailed help you'd need to provide detailed information so do read the sticky at the top of the forum and provide the specs. We may have a better solution.