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iOS10.2 Vuforia 6.1.17 and 6.2.6 video goes out of sync on first recognition.

January 14, 2017 - 9:29am #1

Vuforia SDK Version: 6.1.17 & 6.2.6 -

Description with steps to reproduce: Load the Unity video sample from SDK 6.1.17 or 6.2.6

Load a video with someone speaking. (Test video was MP4 at 640x360 low data rate up to 1920x1080. All showed the same result.)

Set the video playback behaviour to autoplay.

Build in Xcode 8.2.1

iOS 10.2 - The audio goes out of sync on the first recognition but if the target is lost and then found the audio plays back perfectly in sync again. This only happens on the first trackable found.

iPhone 6 is barley noticeable but other devices such as iPad Air and iPhone 5S running 10.2 are considerably out of sync. It appears to be dependent on the processing power of the device but after the trackable is lost and then found again playback is 100% in sync on all iOS devices tested.

iPhone 4S running 9.3.5 played back with no sync issues on first recognition.


Development OS (Mac OS X, Windows, Linux): Mac OS X -

Mobile OS and Version: iOS 10.2 -

Mobile Device Manufacturer and Model name: Most noticeable on iPad Air and iPhone 5, iPad Mini 2. -

Do the Vuforia Sample Applications show the same behavior?: Yes

iOS10.2 Vuforia 6.1.17 and 6.2.6 video goes out of sync on first recognition.

January 18, 2017 - 11:06am #3

If anyone else gets stuck on this i found a workaround for now. I am fairly certain the problem is in the Vuforia iOS plugin lib.VuforiaMedia.a

I think the audio needs to initialise first and this is what is throwing the initial sync out. It would also explain why slower processors are more out of sync as it takes longer to initialise the audio.

The problem remains with the out of sync audio and video on first recognition so i tweaked the TrackableEventHandler and split GetStatus, Paused, Ready and Stopped under the autoplay section and then set the video start time to begin past the end of the video.

This makes the video begin right at the end and then immediately loop back to the start and play in perfect sync.







iOS10.2 Vuforia 6.1.17 and 6.2.6 video goes out of sync on first recognition.

January 16, 2017 - 6:41am #2

Would someone please be able to help me with a work around for this problem? I am happy to pay for a working solution.

If I play the video, then pause it and play it again the audio and video syncs up again. It is only on the first play instance it is out of sync and very noticeable with any talking in the video. This can be seen better on slower devices such as iPhone 5 or iPad Air. The problem occurs on the stock video sample script and tested with 6.1.17 and 6.2.6. I have also tested in Unity 5.4.0.F3, Unity 5.4.4.F1 and 5.5.0.F3 all with the same results. I can't  pin point any specific problems in the script that may be causing the issue. It is working fine on Android with no sync issues, the problem is only with iOS10. I am using Xcode 8.2.1 and testing on iOS10.2

How easy would it be to mod the VideoPlaybackBehaviour script to play the video for 1 frame and then initiate an auto pause, then re initiate an auto play but for the first playback only?  This would be a rough workaround for now but i really need to get something in place in the next few days if possible. The video also goes back in sync if the video starts playing (out of sync), followed by trackable lost and trackable found. After the trackable is found for the second time the video plays in perfect sync again.This could be another approach for a workaround. 

Any thoughts or guidance would be very much appreciated.

Thank you




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