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jacksonmacd

Preview stalls at clip transitions

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Using 4.10

 

Starting with a long, single clip (e.g. 6 hr), add it to the sequence, and pan thru it on the timeline. When I find a section that I want to include in the final product, I copy/paste the clip so I now have two copies. I drag the clip boundaries to the time that I want included, then repeat for multiple clips (e.g. ~50). Then I play back the video using the main arrow under the Sequence Preview window. So far, so good.

 

The problem occurs at some of the clip boundaries: the audio plays back unimpeded, but the video stalls with a "building preview" message. I can understand it happening once per transition, but it occurs multiple times when I play back thru the same transition. This can occur on several of the transitions, but not all of them. And not in sequence - some of the earlier transitions stall, while the later ones play back properly.

 

Further, sometimes a transition plays properly one time, but then falters when I play through it a second time. No recognizable pattern to how it reacts.

 

I've tried "scrubbing" thru the clips when zoomed in tightly, and scrubbing thru the Sequence. Sometimes it helps, other times it makes no difference. I've "clear cache of all unused clips", but it did not make a difference. There is lots of available space on the drive, and the maximum cache size is set to 100000 MB in Tools > Options > Disk. The cache is currently about 7.5 GB for the current project with one source file. The cache had previously been about 18 GB for another similar sized project, and about 28 GB when two projects were cached. It never grew beyond about 28 GB, even after starting a third project.

 

Is there some technique to ensure smooth preview playback?

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Unfortunately you have to wait for the caching. It would take a long time to cache a 6 hr clip.

 

We are considering adding options like only cache the section you've added in to the timeline. So if you only want to cut a small section out of a long clip the rest of the clip don't have to be cached.

 

@Everyone:

 

We take this thread as a suggestion discussion. Please comment if you have any thoughts.

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I thought it might be caching, so I left the computer running overnight, and there was no difference in the disk space consumed in the cache folder. Still getting the stalling behaviour after the overnight session. This morning, I deleted all the cache files via the Options and let the cache rebuild itself. Windows Task Manager reported 100% disk activity for a while, then it fell to zero after some time (guessing ~1 hour). The cache is now about 8 GB, compared to about 7.5 GB before the rebuild, so not a huge change. The stalling behaviour seems to be fixed, so there may have been something corrupted in the cache.

 

I would like to see something changed in the caching behaviour so that it is more responsive to the section that you are currently editing. For the way I am using VP, caching everything that's contained in the current sequence would be beneficial. Or maybe priorize the caching so that the current sequence is done first, then revert to caching the entire file.

 

I really appreciate your responsiveness in considering this issue.

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