RGB range advanced setting incorrect / too dark on new HW AMF encoder on 9070XT (?)

Operating System Info

Windows 11

Other OS

No response

OBS Studio Version

31.0.2

OBS Studio Version (Other)

No response

OBS Studio Log URL

https://obsproject.com/logs/RE2ssWnP9ZrtmLW8

OBS Studio Crash Log URL

No response

Expected Behavior

The limited / full setting should encode with the correct color range. The recordings from a 9070XT look darker than from a RTX3070 with the same settings. See current behaviour below.

Current Behavior

The Limited RGB range option is darker on 9070XT than on an NVIDIA GPU. The color range does say Limited in MediaInfo, but you can still see that video is darker than what it should be.

9070XT on the left, RTX3070 on the right with the same advanced settings (BT709, Limited, NV12, the source window was set to sRGB). My monitor was set to Full range in both scenarios.

The NVENC encoder has much more params exposed, so I tried setting AMF parameters such as profile, color depth, color profile etc:

AMF_VIDEO_ENCODER_HEVC_PROFILE=AMF_VIDEO_ENCODER_HEVC_PROFILE_MAIN
AMF_VIDEO_ENCODER_HEVC_PROFILE_LEVEL=AMF_LEVEL_6_2
AMF_VIDEO_ENCODER_HEVC_COLOR_BIT_DEPTH=AMF_COLOR_BIT_DEPTH_8
AMF_VIDEO_ENCODER_HEVC_OUTPUT_COLOR_PROFILE=AMF_VIDEO_CONVERTER_COLOR_PROFILE_709
AMF_VIDEO_ENCODER_HEVC_NOMINAL_RANGE=AMF_VIDEO_ENCODER_HEVC_NOMINAL_RANGE_STUDIO

but it did not help.

Just to see if the range setting has any effect on the encode, I set it to Full -- the video gets even darker.

Full Range setting

Limited Range setting

Limited Range on RTX3070

Steps to Reproduce

1. Have a Navi48 GPU ? (9070 is probably maybe also affected?) with 25.3.1 drivers (latest) but I'm not sure if it affects other cards.
2. In advanced settings set color format to NV12, color space to rec709 and color range to limited.
3. Either use simple or advanced output settings. Doesn't make a difference.
4. Make sure your source color space is sRGB
5. Record and compare results

Anything else we should know?

Now, I'm not sure if this really is an OBS issue or an issue with the new HW AMF encoder driver on Navi48 GPUs, so at first I thought I'd try here.

Playing the videos display correctly in MPC-HC, but upon editing the videos, you can clearly see they are darker than what they should be. See screenshots above.

Start with the linked OBS log and reproduce the report using a Navi48/9070XT, Windows 11, OBS 31.0.2, NV12, BT.709, and Limited range. Compare the resulting recordings with the RTX3070 examples and verify whether the AMF encoder or its driver applies the range incorrectly; done means the output has the expected brightness and color-range behavior.