Test VLC hardware decoding when audio plays over black video
Use one known-good file and one problematic file to isolate VLC’s decoding setting, then restore the working configuration.
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Establish a working video sample
Open an ordinary local video in VLC. Verify that picture and sound both appear, then play the failing file or authorised stream. Check that a video track is selected. If audio continues and the black picture affects only one format, record VLC’s version, your system and the video codec if you can identify it from the file information.
Change hardware decoding temporarily
VideoLAN documents a GPU decoding setting in VLC’s Input and Codecs preferences. Change only this setting and restart VLC before retesting the same material. If the picture returns in software decoding, check whether high-resolution playback remains smooth and whether the graphics driver is current. Software decoding can be more demanding. Restore the earlier setting if the test makes no useful change.