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Render at source resolution - what it really does?

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Goran Šafarek
Render at source resolution - what it really does?
on May 11, 2016 at 5:40:05 pm

I investigated several threads, but it is still not clear to me how "Render at source resolution" work in the case that Render res is higher then timeline res? I still use Resolve 12.

I know that in Deliver tab (without ticking this function), Resolve will just upscale the timeline.
So, is "Render at source resolution" just up scaling to match the source res (basically just helping you to quickly set the res) or it really use source footage?

Thanks!


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Glenn Sakatch
Re: Render at source resolution - what it really does?
on May 11, 2016 at 9:55:36 pm

it doesn't change where your source is coming from if that is what you mean by
really using source footage.

If your clip in the media pool is 4k, but your timeline is 1080, resolve will render you out a 1080 clip, unless you click that box, then you will get a 4k clip. (the raster size of the source) If your source is 720 and your timeline is 1080, you would get a 720 output with this turned on. Perhaps source "resolution" is not a great term, raster might be better...at least that is how i understand it.

Glenn


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Goran Šafarek
Re: Render at source resolution - what it really does?
on May 12, 2016 at 7:05:51 am

Thanks

If your source clip in Media pool is 4k, your timeline is 1080 and if you set the Delivery back 4k, you will get basically up-scaled footage (confirmed by BMD people). Not a good option. I know that ticking "Render at source resolution" will get you resolution from the clip in the Media pool (that's great option if you you both 2k and 4k clips and you don't have to render them manually in different timelines), but I am still not sure is it up scaled too from 1080 timeline or directly from 4k in Media pool?


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Joseph Owens
Re: Render at source resolution - what it really does?
on May 12, 2016 at 3:54:52 pm

[Goran Šafarek] "I am still not sure is it up scaled too from 1080 timeline or directly from 4k in Media pool?"

Maybe you are unsure of how referenced clip timelines function. The representation of your media on the timeline, regardless of the sequence resolution is always interpreting the source clip as it is accessed through its directory/media path to the source folder. If that original clip does not match the sequence settings, the software re-interprets the source clip in some way to help it make sense (resolution, intra-GOP, aspect ratio, field dominance, and so on). Various NLEs employ a variety of strategies to try to "frame-fit" a circus of formats into a unified structure. Sometimes the clip is re-sized, cropped or squeezed -- and how that adjustment is communicated to the user varies. Sometimes its in a "Motion" tab, sometimes in a PTRZ window... the only consistency is that software developers are totally inconsistent in how this adjustment is applied or communicated -- and that becomes a problem with third-party round-tripping between applications that have their own methods. "Render at Source Resolution" means that Resolve will apply your corrections to the source clip and render it as it exists, straight from the source folder where it resides. This is actually quite helpful if there are PTRZ adjustments that an originating NLE has introduced and then hidden. When the (for example) 4K render clip gets back to the Premiere timeline, it will reappear the way Premiere expects it, and it will down-rez it again, from the 4K original item properties, if in fact you are working in 1080.

When a source clip at a higher resolution is introduced to a timeline at a lower resolution, it does not affect the source clip's resolution -- in your case, it will always be a "4K" clip re-computed for proper display on a "1080" timeline -- but the source remains at its original resolution. If you choose to render out at 1080, then it will be down-rezzed and the graded clip will be a down-rezzed 1080 version of the original. If you choose Render at Source Resolution, then the render is one-to-one from the source clip and you will get a normal 4K graded clip. Of course, its also very helpful not to be working in an alphabet soup of formats.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Goran Šafarek
Re: Render at source resolution - what it really does?
on May 13, 2016 at 7:27:31 am

Thanks Joseph :)


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Steve Mullen
Re: Render at source resolution - what it really does?
on May 18, 2016 at 2:22:40 am

You posted, "When a source clip at a higher resolution is introduced to a timeline at a lower resolution, it does not affect the source clip's resolution -- in your case, it will always be a "4K" clip <> for proper display on a "1080" timeline ..."

1) With UHD h.264, is Resolve's decoder able to decode only a 1920x1080 window from a UHD frame while playing, or does it decode the entire UHD frame and then downscale it to FHD for display?

2) If the full frame must be decoded, then we can use the option to Optimize at various frame-sizes. Choosing 1/4 provides 1080p in the Timeline. Of course it takes time to Optimize.

3) A more fundamental question -- with 4K FS5 footage FCPX is able to real-time play clips without their having been converted to Proxy or Optimized to ProRes. Premiere Pro can do the same with Canon C300 II 4K footage. These format's simply play.

Yet on the same machine (with CUDA) when you bring these kinds of footage into the Resolve they do not play well. Stutters and garbled audio are the norm. Can you, or anyone, explain what is different about the h.264 decoder used by Resolve?

My thought is that although Resolve uses the general compute power of a GPU, it doesn't use the h.264 hardware decoder that all modern GPUs contain.


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Rohit Gupta
Re: Render at source resolution - what it really does?
on May 19, 2016 at 10:03:56 am

Render at source res will render 1:1 from source res. So timeline res is basically ignored in this mode.


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Goran Šafarek
Re: Render at source resolution - what it really does?
on May 19, 2016 at 10:48:53 am

Thanks, now I can delete terabytes of RAW that waited for confirmation of this :)


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Glenn Sakatch
Re: Render at source resolution - what it really does?
on May 19, 2016 at 6:56:18 pm

That statement (deleting raw) scares me.

Just to clarify..if your raw is 4k and you transcode it to low res hd and then cut and color with that media..."source resolution" will result in using low res hd clips,not 4k. The fact that you were waiting for this answer befor deciding to delete your raw source material has me wondering if you are still reaching the wrong conclusion. Perhaps i simply dont understand how this answer would make it ok to delete you raw files in any situation.

If anything i would think it would make you want to keep them..relink to them..then output at source resolution.

Unless your transcodes are all really high resolution as well.

Glenn


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