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4K or 1080 sequence?

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Mark Krueger
4K or 1080 sequence?
on Oct 26, 2017 at 1:24:01 pm

I have 4K footage from a Sony FS5. Final export to BluRay. Not sure if I should use a 4K sequence and render out to 1080. Or import 4K footage to a 1080 timeline and then export that. My 4K footage plays smooth with direct import from card to sequence. Not sure if exporting that sequence to 1080 will take longer this way?
Second Question.
When using 4K footage in a 4K sequence, the clip is showing full frame 100 percent scale. If I scale it to zoom in on footage is it the same as adding that footage to a 1080 time line and zoom in ?


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Jeff Pulera
Re: 4K or 1080 sequence?
on Oct 26, 2017 at 2:21:40 pm

Hi Mark,

I don't see where editing in a 4k or 1080p sequence would make any difference in performance - the computer still has to decode/display the 4k source material either way. If you don't want/need a 4k master, and intend to deliver as 1080p, I'd just edit as 1080p then.

As for zooming - if that is your intention (and no need to deliver in 4k) then definitely edit as 1080p. Right-click the 4k footage in the 1080p sequence and select Set to Frame Size. This will make the 4k fit the 1080 frame, however if you should zoom in, it will still utilize the extra resolution available from the 4k source clip to maintain quality.

Do not use Scale to Frame Size - that will make the 4k footage behave as 1080p, then if you zoom in, you immediately begin losing quality just as you would zooming on 1080p source in 1080p sequence. I shoot stage events in 4k, then edit as 1080p or 720p and can simulate a multi-camera shoot easily. Either cutting between different crops, or using keyframes to animate movements, such as doing a two-minute zoom in on singer from wide to close-up. The motion is almost imperceptible, no way to accomplish that with most cameras.

If you want to "cut" from one crop to another, just Razor the footage at the point where you want to change the scale/position.

Thanks

Jeff Pulera
Safe Harbor Computers


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Mark Krueger
Re: 4K or 1080 sequence?
on Oct 27, 2017 at 3:01:48 am

Thanks so much Jeff.... Just to clarify... if I drop my 4K footage into a new sequence it will automatically make that sequence a 4K sequence. So I need to create a new sequence for 1080p before I drop in my first 4K clip. Then set to frame size for each clip. Viewing the effects panel for that clip I can see the scale which should be something less than 100% and I can then scale without loosing quality.
When I drop a 4K clip into a 1080 sequence I get a red line above the sequence.... do I need to render that before I can work on the clip?
If I use a 4K sequence, and use 4K clips... when I zoom in on the clip will I loose resolution quality if I export out to 1080?


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Jeff Pulera
Re: 4K or 1080 sequence?
on Oct 27, 2017 at 2:06:22 pm

Correct, manually create a 1080p sequence. For instance, AVCHD > 1080p30. Drop your 4k clip into the sequence. Select clip and look at Effect Controls and you will see that it says 100% for scaling. At this point, if you zoomed in at all, you would actually lose quality, as if working with a 1080p source. So now right-click and select Set to Frame and you will notice that Scale drops to 50%.

This means that Premiere is now using the full original 3840x2160 pixels as a source (rather than pre-scaling to 1080 to match sequence) and is scaling that down to 50% to fit it in the 1920x1080 frame. Therefore, if you zoom (scale) the image up to anything between 50-100%, you will lose no quality at all. Every pixel in the 1920x1080 frame is being pulled from the 3840x2160 source, no pixels needing to be duplicated (blown-up).

Note that a 4k UHD image is the same as 4 full HD images. At 100%, you will be seeing one "quadrant" of the original, in 1:1 pixels, so quality would really be identical to an original 1080p image. Only once you scale past 100% would it technically start to degrade, and really you might get to 115-120% and it could still look good depending on clarity/quality of original footage.

I've attached a sample image at 3840x2160, made from 4 HD images. Try it with the above directions in a 1080p sequence to visualize what's happening. Set to Frame, then scale to 100%, then position image so that just one of the 4 images fills the screen. That is the 1:1 pixel mapping and quality right there.

Tip: If you have several clips on the timeline, you can multi-select them and apply Set to Frame on all at once.

RED LINE - that does NOT mean you "need" to render. In fact, it would be a waste of time to render, because as soon as you would do any editing or effect changes, it would go right back to red anyway! Please see this link for an explanation of the red-yellow-green render colors - https://blogs.adobe.com/creativecloud/red-yellow-and-green-render-bars/

To answer your last question about losing quality at export. If you edit 4k source as 4k, and scale past 100%, you are degrading the image at that point. Matters not if you export to any smaller frame size, the damage is done already. Same for editing 1080p as 1080p and zooming in, quality is lost and exporting as 720p or SD will not bring anything back. Only way to zoom and maintain quality is to edit in a sequence smaller than the source. Period.

Hope this all makes better sense now.



Jeff Pulera
Safe Harbor Computers


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Mark Krueger
Re: 4K or 1080 sequence?
on Oct 28, 2017 at 1:20:05 am

OK Thanks so much for taking the time with my questions. I am new at Premier and also with 4K so it is nice to get some help with specific questions. I will try out your suggestions. But I did not find the attached footage you said you included... maybe I am missing where to find this attachment.
You mentioned that I would probably not see much if any loss in quality if I keep the zoom to less than 120%. The zoom scale in the effects panel goes all the way to 200%. With a 4k clip in a 1080 sequence zoomed to 200% I am assuming I would not like that final export? Correct?


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Jeff Pulera
Re: 4K or 1080 sequence?
on Oct 30, 2017 at 2:13:08 pm

Hi Mark,

I didn't attached any video footage, you are supposed to use the still image just to play with how the scaling works.

Something that may be confusing about scaling is understanding how the percentages relate. For instance, a 4k image is exactly as big a FOUR HD images, as seen in my still image in prior post. So one might think that an HD image is then one-quarter the size of 4k. That's true - in total PIXELS...however the X and Y dimensions are only DOUBLE.

Therefore, if you put the 4k image into the 1080p sequence (and use Set to Frame), to see the entire image you set Scale to 50% (not 25%). And to zoom in as far as possible without duplicating any pixels, that setting is 100%. So anything above 100% you are just "magnifying" the image and duplicating pixels. At 200% the image would be getting pretty soft! It would look no different than using a 1080p source in a 1080p sequence and using 200%, same thing.

Please download the image from last post and follow steps I mentioned, then you will better grasp what is happening with the scaling.

Thanks

Jeff Pulera
Safe Harbor Computers


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Mark Krueger
Re: 4K or 1080 sequence?
on Oct 30, 2017 at 3:18:09 pm

OK... Making much more sense to me.... I will let you know if I need more help... Thanks sooo much!! My next question is exporting settings... I don't know if you are able to help here, but I know there is a bit rate settings to make for exporting, not sure what setting I should use for a bluray quality. Any help or advice would be apprecitated. Mark


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greg janza
Re: 4K or 1080 sequence?
on Oct 30, 2017 at 3:22:24 pm

a good starting place would be to select the mpeg2 Blu ray preset in Encoder.

I Hate Television. I Hate It As Much As Peanuts. But I Can’t Stop Eating Peanuts.
- Orson Welles


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Jeff Pulera
Re: 4K or 1080 sequence?
on Oct 30, 2017 at 3:35:32 pm

I'd suggest the H.264 Blu-Ray format rather than MPEG-2, as H.264 is a newer, more efficient codec and will make better video at lower bitrates than MPEG-2.

You can figure out the bitrate based on length of video using a bitrate calculator like this - http://dvd-hq.info/bitrate_calculator.php

Thanks

Jeff Pulera
Safe Harbor Computers


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