Audio out of sync in 4K videos

[lyly19]

When I play 4K videos (MP4, H.265) on a Windows 10 PC using VLC and MPC-HC, the audio gradually becomes out of sync with the video by about 0.5–1 second after a few minutes, even though the same file plays fine on my phone. Is there a way to fix this audio delay issue without re-encoding the entire video?

[Nazrin544]

This usually happens due to hardware decoding or clock drift on the PC. Try disabling hardware acceleration in VLC/MPC-HC and make sure your GPU drivers are up to date. Also check the audio output settings (set them to default/DirectSound). These fixes often stop the gradual audio desync without re-encoding the video.

[MrDoom3412]

It happens due to decoding or sync issues, so first try enabling hardware acceleration in VLC/MPC-HC and update your GPU/audio drivers, as that alone often fixes drift. You can also switch the audio output module like DirectSound <> WASAPI or disable “time stretching”/audio sync options in the player settings. If it still drifts, manually apply a small audio delay in the player or remux the file using a tool like MKVToolNix to correct timing.