Audio not in sync even with offset

[desmond_ho86]

Any reason why the audio is few seconds lag and how I can fix it?

[HereSphere]

For me, usually seeking will fix audio desync issues. Is your playback speed set to 1? Setting it too high can cause audio desync issues. Else, sometimes your audio driver can have issues and a system restart will fix it.

If that doesn't work, then it might be due to a specific video. Does this happen with every video or just specific ones? Videos that are encoded with h264 and greater than 4k resolution might not decode fast enough, so the audio can get out of sync. Also, if you're using an AMD graphics card, then the decoding performance might not be fast enough for very high resolution videos.

[desmond_ho86]

Is it a codecs problem? playback set to 1. cant be audio driver issues, as it works fine with whirligig and vlc player. videos work fine on whirligig. h264 and greater than 4k work fine on whirligig.

[HereSphere]

The software video decoding path in UE4 is slow, so videos encoded with h264 and greater than 4k resolution have issues in HereSphere. I haven't had the time to thoroughly examine UE4's source code to figure out the issue. I'm thinking it could be a video frame copy issue. In the meantime, I'd suggest sticking to h265 encoding for videos greater than 4k. Sorry the app is lacking in this regard.

[desmond_ho86]

is a fix for this possible eventually?

[HereSphere]

Yes, most likely it will require a full implementation of a DirectShow playback path. It probably won't be fixed until much later this year, since I have other priorities at the moment. Just to make sure, are you only experiencing these audio sync issues with h264 videos with greater than 4k resolution, or are other types of videos having issues as well?

[desmond_ho86]

yes 4k resolution and higher. h265 too. any temporary fix for now, or can a change of codec fix it?

[HereSphere]

There aren't many 3rd party codecs for Media Foundation, so you're kind of stuck with whatever Microsoft provides. What graphics card do you have? If it's an Nvidia GTX 10 series or newer card, then you should be able to play up to 8k h265 videos with good performance, since the video card is doing the decoding. If you're using an AMD graphics card, then you might be limited to 4k or 5k.

If you are using an Nvidia card but still getting poor performance and audio sync issues with h265, then it might be some other issue. If you have an audio card, then make sure the audio sample rate is set to 44.1kHz or 48kHz (and not 96kHZ, which will hurt performance). If you have an SSD, try copying a video over to the drive and see if performance is any better. If you used a codec tweaker tool, maybe one of the settings is interfering with Media Foundation's codecs. If none of those solutions work, try using Display Driver Uninstaller to fully remove your graphics driver, and then reinstall a fairly recent graphics driver that is known to work well with VR. Those are the troubleshooting steps I'd recommend.