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Preview Render for Effects

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Thu, 06/18/2009 - 01:48
#1
AlanJames1987
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Preview Render for Effects

Is there a way to do a preview render in Kdenlive?

In every proprietary NLE that I know of there is no way to accurately preview effects and transitions in real time. Instead you can click a button to render all the effects to a temp file that is played in place of the effect. This temp video file is never seen by the user and the appearance of the timeline remains the same as before.

Here is a youtube video illustrating it in Final Cut Pro.

http://www.youtube.com/watch?v=p_SLAncw8kw

If Kdenlive does not have this I think it needs to be added. I don't want Kdenlive to copy any proprietary software's features but this is an essential feature in any NLE and all of them have it.

So does anyone if this can be done in the current release?

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Thu, 06/18/2009 - 01:51
#2
avilla
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Re: Preview Render for Effects

well, kdenlive DOES show effects and transitions in real time :)

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Thu, 06/18/2009 - 02:02
#3
AlanJames1987
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Re: Preview Render for Effects

Not on my quad core computer nor on my dual core laptop, nor my room-mates dual core laptop. However I don't expect it to show effects in real time as no other NLE does. It's not the best practice to watch unrendered effect in Final Cut or Premiere as they often are not accurate.

My question remains the same. Is there a way to do a preview render in Kdenlive?

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Thu, 06/18/2009 - 02:06
#4
avilla
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Re: Preview Render for Effects

no. you can select the zone you want to "preview" with the green slider above the timeline and render just that selected zone

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Thu, 06/18/2009 - 02:24
#5
AlanJames1987
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Re: Preview Render for Effects

That is equal to the "work area" slider in Premiere Pro. It allows you to render a select area of video out to a file. It is NOT a preview render.

I don't know how to describe a preview render other then saying that complex effects rarely play in real time on any system. When you need to see an effect at full resolution in real time without actually rendering a video file you use a preview render.

The video I attached was the best example I can find.

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Thu, 06/18/2009 - 05:52
#6
jmpoure
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Re: Preview Render for Effects

The beauty of Kdenlive is that all effects play in real time. You don't have to export to preview.

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Thu, 06/18/2009 - 07:42
#7
j-b-m
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Re: Preview Render for Effects

In fact, by default Kdenlive (MLT) drops frames to try to be as real time as possible. Your suggestion gave me the idea of adding a "Non real time" mode to Kdenlive.

I just committed the change in svn, so now in the monitor context menu, you can uncheck the "Real time (drop frames)" option, and then Kdenlive will not play in real time anymore but instead create each frame completely, giving a better idea of what the effect does!

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Thu, 06/18/2009 - 17:29
#8
AlanJames1987
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Re: Preview Render for Effects

That is a good idea j-b-m. All proprietary NLEs have a non real-time mode. In Final Cut they call it “Unsafe RT” and this is a step in the correct direction, although it is still not a preview render.

Thanks j-b-m. I will wait for this new feature to come in 0.7.5 or a later release.

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Sat, 06/20/2009 - 10:08
#9
rweilert
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Re: Preview Render for Effects

Although this is my first post in this list ever, just let me add that I was mildly surprised kdenlive didn't offer this feature at all when running it for the first time this morning. I know it from Adobe and Ulead editors, and I only was looking for a hint where to find the option to switch it on in kdenlive :-) The search for an answer brought me here - and I found this thread. So I subscribed to this list to write this down...

Would it be possible to play all effects - even combined ones - in real time anyway? Even in HD formats? On my laptop - single core - not even a simple fading of two DV pieces played smoothly, and I wouldn't have expected it to do. I don't know what my desktop PC will say, but I'll try later.

Just my 2 cents...

Rolf

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Sat, 06/20/2009 - 21:13
#10
AlanJames1987
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Re: Preview Render for Effects

I have not been able to play any effect added to an HD video in real time. However I could not play them in real time in Premiere or Final Cut either. Like rweilert said, combinations of effects would cause even more slow down and this problem needs to be addressed.

There are a lot of missing features in Kdenlive but this is one of the most glaringly obvious ones.

I would like to know if any developers have used the professional NLEs, even if its just to know how they compare to Kdenlive.

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Sun, 06/21/2009 - 07:12
#11
ddennedy
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Re: Preview Render for Effects

The default frame-dropping is not sufficient because it can drop a lot of frames. The non-realtime playback is not sufficient because it typically introduces temporal distortion. Yeah, usually I can get by with either of the above, but I have at least once wished for a more convenient render zone function. The YouTube link does not explain that - it only convers previewing unrendered. Kdenlive does not let you render pieces or do background rendering that will later get reused for final rendering. That is another topic IMO.

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Sat, 02/02/2013 - 18:52
#12
javsalgar
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Re: Preview Render for Effects

Hello everyone,

I am working with HD Footage in my i7 desktop computer, and I am unable to apply effects without a lot of frame dropping. I think that this feature is vital for a NLE. By the way, thank you very much for all the effort on a FOSS NLE. Keep it up! :))

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Sat, 02/02/2013 - 19:32
#13
yellow
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Re: Preview Render for Effects

Consider using kdenlive's proxy feature, spending any time familiarising yourself with kdenlive before posting feature requests and digging up a four year old thread might help. Also I believe some work is being done on GLSL effects in MLT so that may help in the 'near' future.

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Sat, 02/02/2013 - 19:53
#14
javsalgar
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Re: Preview Render for Effects

Thank you very much! I just searched on google and I found this thread. Sorry for any inconvenience :(

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