Forum Discussion
Audio and Video out of sync when using Seekbar
I have a number of different courses where I have recorded video using Storyline. I have then exported the video, converted it to an audio file, edited the audio with Audacity, and then inserted th...
Hi all,
Thanks everyone for your patience.
We have been actively investigating this specific issue for some time now and are now able to share an update on our progress with you.
The sync issue stems from a limitation with the way Flash handles video. It is only possible to sync playback to the nearest video keyframe. Keyframes may occur multiple times per second, but in some videos it may be several seconds between keyframes. If the seek bar is moved to a position that does not correspond to a keyframe, the timeline will play from the precise position selected but video will only play back from the nearest keyframe, causing the sync issues described above.
The Storyline team is working on a fix which is currently slated to be included in the next update for Storyline 2. The fix works around the Flash limitation described above by limiting seeking during video playback in Flash to positions that line up with the video’s keyframes. We will share further information on timing for the update (which addresses several other customer-reported issues as well) on this thread once it has gone through our usual testing process.
In closing, I wanted to assure everyone that we closely monitor these discussions and take the issues you report incredibly seriously. The seven major updates we’ve shipped for Storyline 2 since its initial release have addressed a long list of customer-reported issues at no cost to our customers. You have our commitment that we will continue to actively evaluate and fix reported issues for the lifetime of the product.
Thanks for the real response Ashley. As your usergroup, we definitely appreciate the information.
Ashley, thank you. It's a relief to finally see this conversation moving in
a more productive direction.Cool. I created a work around for this.
- Put a 50% transparent rectangle over the seekbar.
- Create separate start/stop controls that sit on top of the start/stop controls of the seekbar.
- Create triggers assigned to the "faux" stat/stop controls that would start and stop the timeline.
Benefits:
- Still get to see the seekbar advance and the time indicator
- Starting and stopping timeline doesn't throw any animated effects out of wack
Drawbacks:
- Not a true seekbar since you can't jump around in the movie.
Hope this helps.
- Michael
Thanks Ashley and to your team for looking into the issue and providing extra detail.
Another potential workaround that I can think of would be to add additional keyframes to your video. This will increase the video file size but depending on the content you may be able to sacrifice other settings (bit rate) to keep the file size down.
Best to do this at the output point to get the best quality rather than using already compressed video.
In an application such as Adobe Media Encoder you can set the keyframe distance to 1, for example and re-output your video.
In a 29 Frames Per Second video this would insert 29 keyframes every second. This should keep the sync very close. You could set the keyframe distance to a larger number eg 15, that would mean there would be keyframe every half second.
I am sure there are other video rendering tools out there that would let you add keyframes but always best to do it from the Hi Res source.
I have to test this theory but I am certain it will work.
Hi Ashley! I'm having issues with this problem in a current course , and I reeeeeaaalllly wanted this to be a fix, so I tested it. I didn't get very good results though.
I went ahead and created two versions of the same video, one with keyframes at 90 and one with keyframes at 5. And i published both courses at 29.97fps (pretty standard). I separated the audio from the video and posted each video on a separate slide under the exact same conditions. I got what looks to be the exact same amount of ... ummm... 'un-synced-ness?'. And it's pretty big chunks of time, even though a video at 30fps with keyframes at every 5 should have 6 keyframes/second, and therefore only a .2 second disconnect with the audio at most. I posted my test version here.
www.ezlearnin.com/Clients/Test/keyframes/story.html
I'm attaching the source file as well. To me, it was really weird that video lag was pretty much exactly the same at each point when comparing the videos, BUT, the lag was longer at the first point than it was at the second and third.
The html5 version is spot on though!
http://www.ezlearnin.com/Clients/Test/keyframes/story_html5.html
So, I guess with that said, I'm wondering if there might be some additional information regarding the keyframe issue that was left out? Or maybe I'm missing something? I'm pretty handy with Adobe Premier Pro, so any further insight would be helpful.
P.S.... Much appreciation for your peaceful moderation of these kinds of issues! It seems like you're always moderating the issues with no end in site. I'm sure it's a tough position to be in. :(
Thanks Ashley!
