[Cin] Editing 4K content targetting 1080p output

Igor BEGHETTO igorbeg at visi1.org
Sun Jan 30 10:33:11 CET 2022

Stefan, I think you are doing a bit of confusion.

When you are using Proxy the Scale factor is used for scale down that 
video. Your 4k (3840x2160) video, with Scale=1/3 will be scaled to 
1920x720, not 640x360.
Cinelerra-GG don't know you are using a different Project format 
(1920x1080) and it is right so.

The Z value of the Camera tool don't use pixels but rate. It doesn't 
matter if Proxy is enabled or not. When Z=0.5 (50% if we want to see it 
in percentage), the frame will be scaled (up, if Z >1, or down, if Z<1) 
of that value.
It is different for X and Y because them use pixels but the values are 
switched to the ProjectFormat/ProxyScale.

When Proxy is enabled, if you want open a clip in the Viewer, you must 
dragging and dropping (or double click) that clip from Resources/Proxy, 
not from Resource/Media.
Because your project is 1080p size and  you are using a 4k video, the 
Viewer shows that clip zoomed. The Viewer window aspected a 1080p video, 
not 4k video. There is a fantastic Workaround for that (... and Thanks 

Before I write the Workaround, had you thought of one of the two ways 
below (sorry if I allow mysef)?
Using a Project format size for 4k and working onit with Proxy 
(Scale=1/6?). Rendering out to 4k and, after, converting the Final video 
with a tool (Handbrake?) or with Cinelerra-GG.
Converting your video from 4k to 1080p before loading that video in 
Cinelerra-GG. You will gain performance after. but loose time for 

Yes, for #1 and #2, you waste time for conversion.

=== Workaround ===
Start from an empty Project 1080p.
- In Resources/Media RMB (Right Mouse Button) on the clip icon.
- Select "Info..." option.
- In Asset info window on "Video:" section, click on "Resize" button and 
change the Scale to 0.500x0.500.
- Enable/Set Proxy.

when Proxy is enabled you must drag &drop (or double click) from 
Resources/Proxy, not from Resources/Media, to load that clip in the Viewer.

Sorry for the long texts.
I have to go for a drink because of dry throat. ;-)


Il 29/01/2022 14:34, Stefan de Konink via Cin ha scritto:
> In my curious "document everything you don't understand in 
> Cinelerra"-adventure. I have now content that is shot in 4K. For speed 
> purposes I am (usually) successfully using the proxy functionality. 
> The proxy is configured to 1/3 of the size (640x360).
> Problem 1;
> With the proxy *enabled* I drag a video in the timeline.
> Since my target format is 1080p I reduce the size of the camera on the 
> video track to Z=0.170 to see the full frame (using the proxy). But 
> when I disable the proxy, the Z value should be set to 0.500 to fill 
> the frame.
> If I would instead *disable* the proxy, drag a video in the timeline. 
> Set the Z value to 0.500, I am able to start the proxy and get the 
> desired effect that I want: both proxied video and original video are 
> of the same size in the compositor.
> Problem 2;
> When the proxy is disabled, the viewer shows the clip in the original 
> resolution. I think this is expected. Now when I enable proxy editing, 
> and then open the same clip in the viewer, the resolution is scaled 
> (zoomed in). It feels like this is all related to the output 
> resolution being 1080p, scaling is applied to the proxy, and the meta 
> data is not used consistently. ... ... ... Nope. It shows it in 1080p, 
> the project resolution. This is not expected from a viewer in my opinion. 

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