Wrong black level on video exported from Premiere
Last night, I was exporting a video I’ve been working on. And since I’ve lately become very interested in color correction in video, I was not very pleased to see that the black level in the video was shifted to brighter, as I played it back in VLC. It looked like the black was clipped at broadcast levels. In short, it looked like the black was set to (R,G,B) (16, 16, 16) instead of the (0, 0, 0) that I had be working towards.
Searching the web I found lots of people having problems with gamma in mp4/h264 files from Premiere exported with QuickTime, but I didn’t use QuickTime, and a gamma shift wouldn’t move the black level. I also tried a different codec, and so my thoughts started to shift towards VLC.
It turns out that VLC was partly the problem. In my search I found this blog entry by Ben Krasnow which pointed me in the right direction.
In the NVIDIA Control Panel you can go to “Adjust video color settings”, “How do you make color adjustments”, I chose “With NVIDIA settings”, clicked the “Advanced” tab, and set the dynamic range to Full.
Or, in VLC I could go into Tools | Preferences | Video and disabled “Use hardware YUV->RGB conversion”
Seems like VLC is not capable to tell the NVIDIA drivers that it wants the full range, and so the driver clamps it to broadcast safe.