Video Rendering#

Screenbox renders video through LibVLC's Direct3D11 output module, integrated into the UWP environment via a XAML SwapChain panel. The rendering pipeline is initialized on a background thread by PlayerElementViewModel, which assembles LibVLC command-line arguments (including upscale mode) and hands them to PlayerService.Initialize(). LibVLC is created with the --aout=winstore audio backend and any SwapChain options required by the UWP host.

Video Upscaling (d3d11-upscale-mode)#

Screenbox exposes three upscaling modes via the VideoUpscaleOption enum 1:

The --d3d11-upscale-mode argument is appended only when the setting is not Linear 2. The setting is persisted under Advanced/VideoUpscale and requires an app relaunch to take effect, because LibVLC is configured at initialization time 3.

Known Issue: Black Screen with RTX Video Super Resolution (HEVC 10-bit)#

Symptoms#

When the upscale mode is set to Super (RTX VSR), HEVC (x265) content — particularly 10-bit or high-resolution files — plays with audio only; the main video window is black. The mini-player/playlist preview is unaffected 4. H.264 content is generally not affected 4.

Confirmed affected configurations:

• RTX 4070 and RTX 5070, NVIDIA driver ≥ 572.16 4
• Windows 11 25H2 4

Root Cause#

This is an upstream LibVLC bug in the Direct3D11 module. The Screenbox maintainer identified the root cause in Direct3D11Open: when an external Direct3D device is used (as in UWP), D3D11_GetDriverVersion is never called, so the device is never populated with driver version info. Without that, D3D11_UpscalerCreate cannot create the RTX scaler and the render falls back to black 5. The same black-screen symptom affects VLC 3.0.21 itself; MPC-HC is unaffected because it uses a different rendering pipeline 4.

There is no detection or graceful fallback in Screenbox today — when scaler creation fails silently, the main render window simply shows black 6.

Workarounds#

1. Disable RTX Video Super Resolution in NVIDIA Control Panel or switch the Screenbox upscale setting back to Linear 6.
2. Disable Variable Refresh Rate (VRR) — may resolve the issue in some configurations 6.
3. Override hardware decoding via Advanced Mode → Global Arguments: --avcodec-hw=none (software decode) or --avcodec-hw=d3d11va (D3D11 hardware decode) 6.

Status#

No fix is available at the Screenbox level. The bug must be resolved in LibVLC's Direct3D11 module. Tracked in issue #729 and issue #549. A UX mitigation (detect scaler failure → notify user or auto-fall back to linear scaling) has been proposed but not yet implemented 6.

Key Source Files#