[Cin] Editing 4K content targetting 1080p output

Stefan de Konink stefan at konink.de
Sun Jan 30 11:37:22 CET 2022

Hi Igor,

There are multiple reasons not to convert the 4K content to 1080p;
 1. Obviously when scaling an h264 file, it must be re-encoded.
    Since Cinelerra does not support things like 'lossless cut' even it it 
    every composing step there after will require a re-encoding of the 
    medium. The quality will degrade.

 2. The 4K content allows the editor to crop in post. Hence, I can
    zoom in, or track content while still having a lot of headroom to do so
    without loosing visible quality, including rotation.

There is a simple reason not to render out 4K;

 1. It takes *much longer* to encode H264 in 4K.

There are several issues with the proxy.

 1. The proxy view looses media. Practically speaking, when by files are in
    folder A, and I add some files from folder B, my proxy does only 
    files from folder B. (this can be seen in the screenshot,
    but I was not able to reproduce it in the video)

 2. As you can see in the screenshot, some of the files that remain have 
    'green' thing around the proxy.

On Sunday, January 30, 2022 10:33:11 AM CET, Igor BEGHETTO via Cin wrote:
> 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 640x360 is what the proxy window shows. I agree that the output for 1/3
should be 1/3 of the input video. But I could *fully* understand that 
-vf scale=w:h is applied to the proxy resolution. I would find that 
as well.

> 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.

I guess this forces me to make a screen recording what I see happening.


> 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 GG!!!).

Is there any technical reason not to have the viewer play any clip in the
*media's* resolution. Regardless of proxy or project setup?

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