kdenlive render pipeline (was Re: smart encoding)

[Evert Vorster]

Hi there.

There was a little trick that I was doing on a virtual machine some time
ago, where I would set the project resolution to the proxy resolution, and
my proxy resolution was exactly the display window resolution, so I was
avoiding any scaling whatsoever. Editing was indeed very, very fast, even
on a single CPU virtual machine.
I would then set the project resolution to the desired resolution before
doing the final render.

The drawback of this approach is that title clips are produced at the wrong
resolution, and pan/zoom was affected.

In short, I agree, there is a lot of speed gain to be had here, which would
open up or improve the experience of video editing for a lot more people on
older/slower hardware.

-Evert-



On 29 September 2017 at 00:30, alcinos <french.ebook.lover at gmail.com> wrote:

> Hi,
> So I think you guys are talking about different things. Harald talks about
> prerendering, where you basically precompute all the frames for a portion
> of the timeline to play it faster. That should of course remain as it is,
> because the intent of this is to see how the final clip would look like.
>
> Mikko seems to be talking about instant preview, aka what shows up in your
> timeline monitor when you press play (even if the portion you're playing
> wasn't pre-rendered).
> That is true that there is currently a waste here, especially when working
> with proxy clips. Say for simplicity that you're project profile is 4K, and
> you're proxy are 720p. Then currently, if I am not mistaken, if you place a
> proxy clip on the timeline and play it, then kdenlive computes the frames
> in the project profile, which means that the clip must be scaled up to 4K,
> and then down again to whatever size your project monitor currently is
> (probably less than 720p). If there are effects applied in the meantime, I
> let you imagine what a waste this is…
> I'll have a look to see if we can improve thing for kdenlive 17.12 with
> that respect.
>
> Cheers
>
> 2017-09-28 20:08 GMT+02:00 harald.albrecht <harald.albrecht at gmx.net>:
>
>> For my workflow, I'm glad that the render pipeline is as is: because I
>> need to resize the timeline height while working on my project this would
>> otherwise invalidate the whole prerendering data. The downscaling is cheap,
>> while the prerendering is expensive. I fail to see how changing the
>> pipeline would improve the situation except to where low end hardware is
>> used which even cannot scale down in realtime.
>>
>> Best regards,
>> Harald
>>
>>
>> -------- Ursprüngliche Nachricht --------
>> Von: Mikko Rapeli <mikko.rapeli at iki.fi>
>> Datum: 28.09.17 13:53 (GMT+01:00)
>> An: kdenlive <kdenlive at kde.org>
>> Betreff: kdenlive render pipeline (was Re: smart encoding)
>>
>> Related to this, kdenlive render pipeline for time line preview on
>> the monitor GUI component is far from optimal. First the clips are
>> rendered
>> to project profile and then rescaled to fit the monitor screen size.
>> Also with proxy clips.
>>
>> IMO better would be to render project previews directly to the
>> current monitor/preview size without passing through current project
>> profile except for frame rate.
>>
>> For final rendering, naturally, the project profile should be used.
>>
>> https://bugs.kde.org/show_bug.cgi?id=384764
>>
>> -Mikkoo
>>
>
>


-- 
Evert Vorster
Isometrix Acquistion Superchief
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