Maintaining Quality for Hard Drive storage/TV viewing

Hi there,

New Shotcut user here (have not done much editing since I stopped using iMovie due to them gutting the editing tools).

I have a 1080p quality film video input that I have run through Shotcut to get rid of a godawful tinge (great to have some fine-tune video tools again!). Having successfully removed the tinge, I have tried multiple export formats (all at the Video’s original input values [and even tried a 4K preset]; 100% quality; with lib.264) and cannot stop the export being incredibly lossy.

For information, I want to store the movie on a 4TB hard drive (so space is not an issue), which plugs into my HDTV. So it is not needing any compression for YT, etc.

Any assistance would be incredibly appreciated.

Thank you!

libx264 at 100% is lossless, meaning the quality degradation you’re seeing is not due to compression or the codec. So the next step would be to take a look under the Settings menu > Video Mode, and verify what the timeline resolution is. It sounds like the project was authored on a 720i timeline and then scaled up to 1080p at the time of export.

For us to be the most useful, could you send us the Settings > Video Mode setting you’re using along with screen captures of the four Export > Advanced tabs? Video/Codec/Audio/Other

EDIT: Technically, the right way to find the timeline resolution is to click on the Master track head (it is directly above the V1/V2/V3/etc track heads in the timeline window) then go to the Properties panel and see what the resolution is.

So, the VM I am using is set to ‘Automatic’.

I have attached the Video and Codex tabs (I am not fiddling with Audio or Other) and I have also attached the timeline resolution (which seems to be coming up automatically as the settings for Video).

Thank you so much for your help!


Good news:
We know where the problem is now. The project settings are catastrophically messed up. The 1080p input video is being scaled down to the timeline’s 1280x528 resolution, then the 528p is being scaled back up to 1080p at the time of export using bilinear interpolation, which of course is meant to be fast rather than look good. Also, the colorspace of the timeline is BT.601 instead of BT.709, so all of the colors will be shifted into the duller-looking SD gamut as well. It’s a total disaster.

Bad news:
There is not an easy fix. Generally speaking, it is best to set the Settings > Video Mode to an actual value rather than leave it on Automatic so that the timeline will be the resolution you want regardless of what media you drop onto the timeline first. In Automatic mode, the timeline takes the format of whatever video you drop on first, which may not be representative of your entire project. This is probably why the timeline has the settings it currently has. It wasn’t anything you did wrong specifically.

Fix #1:
If you are handy with a text editor (such as Notepad++), open the .MLT file and change the third line (it starts with <profile) such that width="1920" and height="1080" and display_aspect_num="16" and display_aspect_den="9" and colorspace="709". Note that if you had any filters or keyframes that depended on pixel positioning such as text or Size and Position, then those coordinates will not be scaled to the dimensions of the new timeline and this fix won’t work. Do Fix #2 instead.

Fix #2:
Create a brand new project with the Video Mode set to the output format you want from the start. Then rebuild your project from scratch. Yeah, pretty awful.

Regardless of how you fix the timeline, recommendations for the export settings would be Video > Interpolation > Bicubic and Codec > Quality > 68% to 80% depending on taste. Quality at 100% is much slower and a much bigger file for no visually perceptible gain.

Good luck!

Thank you SO MUCH for that advice! Something so basic that I missed facepalms

The only filters I have been adding have been colour temp and saturation filters, so I will try Fix #1 and see if that does anything for me before sigh restarting from scratch (some of the shots had more tinge in them then others, so rather than one long run on the timeline there are about 100-odd clips!!!)

Also, thanks for the advice to change Interpolation to Bicubic. I will see how it goes.

And let you know, of course!

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