Changing Clip Speed Creates Audio and Video Syncing Problems

I was having the same, I had all the clips muted and various speeds throughout a 2 minute video clip, when I added the music and exported the movie I would get original sound clips that I muted coming through with the music. I found that when I reverted all the clips back to 100% speed this problem disappeared. However when the movie was only 1 minute long I did not have this issue.

Use only the speeds indicated by the slider. Audio glitches may arise in your exported movie if you type in your own custom speeds. The slider presets are 12.5%, 25%, 50%, 100%, 200%, 400% and 800%. Don't manually enter speeds such as 33%, 89%, 125% etc. The glitch is not evident in preview - only in the exported movie.

This shouldn't affect the original poster who appears to have used only the slider presets.

John

This has happened to me a ton in the last few days...hopefully doing what John says will help because it is very frustrating.

If you have used your own custom speeds, I'm sure your audio issues will be resolved if you adjust such speeds to any of the slider presets. This is a well known bug in iMovie (or perhaps an interface design fault). There have been many reports about it in the forum - and just as many happy customers once the adjustments are made!

John

I have ALWAYS had similar problems, but not specifically with audio, but rather just with the clips that I'm slowing down - They jump seemingly randomly between parts of the source clip. In otherwords, if I have a 60 second clip, and I split it at 20 seconds, and 25 seconds, and then slow the 5 second middle part down to 50% using the slider (so that 5 seconds of video is now 10 seconds long), that 10 seconds jumps around, and shows seemingly random sections from my video. If I change the speed back to 100%, the clip goes back to normal. This is REALLY frustrating... Has anyone seen that??

FWIW, I dont know if the audio is messed up too because I've already separated it and deleted the audio track (I'm going to do a voiceover for the final product and dont need the original audio at all)

Thanks!

I haven't seen that behaviour, but I very rarely use speed changes (probably only in a test project which worked OK). You could try deleting iMovie's preference file - post back if you need further information regarding this.

Are you sure you haven't made any custom speed changes elsewhere in your project (although this should only affect the audio - not video - on exporting the project)?

John

I will try to find the preference file to delete.. If you know offhand where it is, let me know, and I'll give it a shot..

I definitely haven't made custom changes elsewhere in the project. Matter of fact, I can start a new project, and see the same thing happen.. It's very strange.. I thought I had it figured out - I thought it depended on whether I split the video first, or slowed it down, but it doesn't... it seems to be random.

More specifically, what I'm WANTING to do, is to take a whole clip, slow it down to 33% or 50%, and then in several places, just right-click and insert a freeze frame, to increase the delay to allow for more voice-over.. I'm describing karate moves, so sometimes 33% isn't slow enough to complete the description...

Do you know of a screen recording program I could use to demonstrate my issue? I could show a short clip "working", and then slow it down, split it, and almost guaranteed, I could show it jump around randomly.

Thanks for helping! I'm kinda lost here.. I'm a long-term Windows (or rather an even older DOS) user who chose a MAC this time, mostly for the "It always works" factor when I'm trying to edit video, and I'm not really getting that advantage yet!!! 🙂

I will try to find the preference file to delete.. If you know offhand where it is, let me know, and I'll give it a shot..

The preference file is in your user (Home) folder Library>Preferences and is named "com.apple.iMovie8.plist". First close iMovie, then trash this file. When next opened iMovie will create a new file with the default settings. To change any settings, in iMovie's menu go to iMovie>Preferences and adjust settings under each of the 4 tabs.

When iMovie is acting abnormally, usually the first troubleshooting trick to try is trashing the preference file. This applies to any version of iMovie. The preference file can become corrupted at times, particularly when iMovie quits unexpectedly (crashes). Refreshing the file, as described, will often fix any problems.

You mentioned using a speed of 33%. I would definitely avoid doing this within iMovie, as it is not one of the preset speeds that appear on the speed slider - 12.5% and 25% are OK though. A free program like JES Deinterlacer can do custom speed changes and the resulting file can be imported to iMovie. A search will find it for you if needed, otherwise post back for more information.

First things first though - try deleting the preference file, then report back. Sorry to hear you are seeing this issue - things generally work great with my setup (although I rarely use speed changes).

PS Just thought of something else. You mentioned inserting freeze frames within the slow motion sequence. Possibly that is what is causing the problem. Do you see the jumpiness before adding the freeze frame?

John

Message was edited by: John Cogdell - added PS

Thanks - I did find that preference file.. I renamed it, and iMovie reinitialized completely.. Still have the same trouble... Other than renaming my preference file back, is there a way to get my old projects back?? For now, since it didn't help, I put the preference file back..

In regard to the speed.. I was mistaken - I must have been using 25%, not 33%... I definitely am using ONLY those values offered by the slider, as I've seen those warnings before..

As for the freeze frames, it does happen whether I just split the video and slow it down, or do the freezeframe, so I'm lost...

Thanks for helping!

I just ran a short test by slowing down a clip to 25%, then inserting several freeze frames at random points. The full sequence ran smoothly, other than one section where the video was being zoomed out. On this section the slow motion effect was quite jerky, which is to be expected. One lesson learnt - don't slow down clips that contain zooms (and probably pans). So, I really can't replicate your "jumpy" video problem on my setup using that simple test.

That's odd that you lost your projects when iMovie was re-initialized. I notice that you renamed the preference file rather than trashing it. I guess this would have the same effect as trashing, given that iMovie wouldn't be able to find it and would therefore create a new one. Some users recommend moving the preference file to the Desktop rather than trashing it. Then if things go awry, you can move the file back to its usual location. Any of these methods should work.

So, in your case, you are saying that putting the old preference file back in place didn't allow you to see your old projects? In any event, the creation of the new file automatically by iMovie should still have given you access to all your Events and Projects, to the best of my knowledge. I haven't heard of other users having this type of issue when recreating a preference file.

Here's a link to an Apple Support article regarding iLife Troubleshooting Basics. Among other recommendations, it includes the tip about removing the preference file. It also includes information on individually reinstalling any iLife applications that are troublesome (for example, iMovie).
http://support.apple.com/kb/TS3249

Hope this helps in some way. It seems to me that you may have to reinstall iMovie.

John

I think a reinstall will be my next step then... You seemed
surprised that I lost my projects when I started a new preference file.. I also lost my events, but they all came back when I put the original prefs file back. If that was not what should have been expected, that's even more reason for me to reinstall I guess..

Thanks!

Here's an interesting blog by Alfred C Chen from Sun Microsystems entitled "My Corrupt iMovie Project":
http://blogs.sun.com/alfredc/entry/mycorrupt_imovieproject

Particularly look at the 5 steps he went through with Apple technical support, listed at the end of his article. This may be helpful, but try at your own risk!

Yes, I was surprised that you "lost" your Projects and Events after iMovie created the new preference file. That is unexpected behaviour - perhaps there are some unusual circumstances prevailing in your case. Even re-installing iMovie shouldn't cause you to "lose" your existing work. Unless you've moved (or originally saved) them to another drive, Events are stored in your Home folder Movies>iMovie Events. Likewise, Projects are stored in Movies>iMovie Projects. When newly installed, iMovie should automatically see these Events and Projects, as it will look for them in your Home folder and at the root level of any connected drives. Similarly, it should look for movies in iPhoto and create thumbnails in the item "iPhoto Videos" at the top of your Events list.

Perhaps you have moved your Events and Projects to some other location, other than those I've mentioned here. That's possibly why iMovie is not seeing them after newly creating the preference file - it expects to find them in the designated locations.

John

Message was edited by: John Cogdell