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Rendering files with speed effect

vcollins
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Rendering files with speed effect

Fri May 23, 2014 7:14 pm
Hello everyone. I have a quick question about rendering files that have been sped up. I'm using the speed effect under the Motion category, and I'm trying to speed up a clip that is about 11 minutes long into a 2 second clip. Since that is a huge difference, I have to speed up the clip once, render it and then reapply the effect to get it to be the duration I want.
I noticed that when I rendered the clip, the last frames get cut off, even though I see them on the preview panel.
I've tried rendering the clip in different formats, but it gets cut off anyway. So how can I get this to work?
Is there a specific format I have to render the clip in? Is this just a side effect of trying to condense such a long clip into a few seconds? Should I cut the clip at the last frames and treat them seperately?

In the preview panel:
Image
In VLC:
Image
User avatar TheDiveO
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Re: Rendering files with speed effect

Sat May 24, 2014 12:24 pm
This is probably not an issue of the render format, but instead an issue of the source clip format.

I've learned (only recently) that not all source clip formats are considered equal when it comes to the speed effect and searching within video streams. H.264 doesn't work reliably, I had all kinds of issues and Dan Danedy is very clear about not improving H.264 search support. The solution is to transcode your source footage into DNxHD footage. The speed effect then should work as expected. Right click on your source clip in the project clip list and choose transcode, then DNxHD and the bitrate you want. Then use the transcoded clip instead of the original clip.


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vcollins
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TheDiveO wrote:This is probably not an issue of the render format, but instead an issue of the source clip format.

I've learned (only recently) that not all source clip formats are considered equal when it comes to the speed effect and searching within video streams. H.264 doesn't work reliably, I had all kinds of issues and Dan Danedy is very clear about not improving H.264 search support. The solution is to transcode your source footage into DNxHD footage. The speed effect then should work as expected. Right click on your source clip in the project clip list and choose transcode, then DNxHD and the bitrate you want. Then use the transcoded clip instead of the original clip.



This worked much, much better, thank you! There is still a little bit of cutting, but its not even close to as noticeable as before.
You're awesome!
User avatar TheDiveO
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Nope. Thanks should go to Dan Danedy who bluntly told me that he isn't going to improve searching in H.264. xD

I just had a small project of mine done these days where I had to speed up H.264 footage ... so I tried what I have read elsewhere and DNxHD seems to work quite good.


TheDiveO on YouTube: diving videos and aerial (quadcopter) videos, all made with Kdenlive.
TheDiveO Blog: know-how about Protune-grading in Kdenlive, GoPro HD Hero 3, DJI Phantom Quadcopter, full face mask diving, and some more...

 
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