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Alpha Matte exporting issue

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CapitalF

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Alpha Matte exporting issue

PostMon May 20, 2024 6:19 pm

Hello,

I'm working with a tech client where we're needing to do all kinds of processes and camera settings that I don't encounter on any other project. Essentially, we're working on a project where we work with tons of footage of actors on green screen and when the footage is fully uploaded onto our system, we transfer footage onto an SSD, it goes to the client, and they ingest footage into their system where their algorithms key out the green for us. We almost never have to do any post.

However, some of the footage they've taken in in the past doesn't take with the green screen and they've asked us (going forward) to key out the green on rejected clips and send them black and white alpha matte footage for each session of actors. We have Da Vinci 18 and I've been using Fusion to key out the green, leaving it on the Matte view mode, and exporting. I was doing a test export of a session and it's been predicting 3 days to export. I thought it would tick down to less than a day but a few days later, it's sticking to that timeline. If it was the regular non-B&W footage, it would've gone much faster.

The footage itself is 4k at ProRes 422 HQ. I've been exporting at that same resolution and am trying to figure out if there's a setting to make the footage export faster or any tips since it might be unworkable in practice. A lot hinges on this working work-wise and I'm not a Da Vinci expert.

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KrunoSmithy

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Re: Alpha Matte exporting issue

PostMon May 20, 2024 8:04 pm

CapitalF wrote:The footage itself is 4k at ProRes 422 HQ. I've been exporting at that same resolution and am trying to figure out if there's a setting to make the footage export faster or any tips since it might be unworkable in practice. A lot hinges on this working work-wise and I'm not a Da Vinci expert.


What format are you required to deliver the files? EXR image sequence or something that supports alpha matt, or just black and white image and they will use it to extract the alpha from luminance values?

Either way, I don't know how you are keying it all, and there are usually speed penalties the more complex the key session is and some of it could be optimized in workflow.

But in regards to export itself. The fastest way I know how is using a loader and saver nodes in Fusion page, avoiding resolve all together. Use a loader node in Fusion page to load up your footage, do you key process, and use at the end saver node to save it to disk as image sequence. Default is EXR, but you can also change it to jpeg or png if you change the extension of the file name in saver node.

Another thing that might speed things up, quite a bit at least for me, is to do your key, set up saver node, and before you go to menu Fusion: Render all Savers to render it. Save your project, close resolve. Open back up and don't preview the saver node or anything, live the viewer blank and just go to Fusion menu, Render all savers. And let it render. I don't know why, but for me this reduced render time by crazy amount compared to going via media out and via deliver page. Give that a try.

For simple keying process, you can also try to do it from color page, directly using keyer there. But if you work in Fusion, try saver and loader nodes and at least for me on windows, closing the resolve and opening it before rendering saver node, with no preview speeds things up quite a bit. I went on one comp from 7:33 h to 25 min.
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Bryan Ray

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Re: Alpha Matte exporting issue

PostMon May 20, 2024 8:14 pm

Kruno, have you submitted a bug report about that that save-and-reload process you described? That definitely sounds like something that ought to go to Support.
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KrunoSmithy

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Re: Alpha Matte exporting issue

PostMon May 20, 2024 10:10 pm

Bryan Ray wrote:Kruno, have you submitted a bug report about that that save-and-reload process you described? That definitely sounds like something that ought to go to Support.


It may not be a bug. It could be just a happy accident, that I chanced upon by trying to deal with long render times on a slow machine. I am using an old machine for Fusion and its 6GB of GPU RAM, 16 GB of RAM and no extra disk space, so I have turned off caching to hard disk to not fill up hard drive and only rely on limited GPU RAM. My theory is, and this has be talked about on this forum, that when I only use GPU to preview render it should ideally render a portion of the timeline that it has cached and than start over. But sometimes there is too much stuff to do in a comp and it just can't handle it.

When I use saver, I used to have viewer showing the process of rendering in the background with saver node in the foreground . Than I found out that if I turn off HIQ mode it gets faster rendering times. So eventually I didn't preview when I use saver node, and this helped a bit but not too much. I'm guessing is that graphic card has a problem previewing the rendering and soon fills up and if it has to service the saver node as well it is slow. Or crashes. But I think what might be happening is that when I set up saver and everything and close the Resolve, the GPU RAM is cleared out. And when I open Resolve, go to Fusion page and just click to render all savers with no preview in the viewer, because no node is selected, than GPU probably only has to render out saver output, one image at the time, which is much less of a problem for it, because it refreshes itself each frame.

To be fair, I had problem with my last comp taking too long to render, so I chanced upon that tricked when Fusion crashed and I started rendering saver nodes but forgot to click on any node to preview it. I only did three revisions of the same comp, that all significantly reduced rendering time for that comp when I use the described method. But I haven't tested it beyond that since I only discovered this two days ago. I'll do more testing, or others can as well. Maybe its a happy accident that I'm not complaining about. Will see.
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CapitalF

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Re: Alpha Matte exporting issue

PostTue May 21, 2024 12:01 am

KrunoSmithy wrote:
CapitalF wrote:The footage itself is 4k at ProRes 422 HQ. I've been exporting at that same resolution and am trying to figure out if there's a setting to make the footage export faster or any tips since it might be unworkable in practice. A lot hinges on this working work-wise and I'm not a Da Vinci expert.


What format are you required to deliver the files? EXR image sequence or something that supports alpha matt, or just black and white image and they will use it to extract the alpha from luminance values?

Either way, I don't know how you are keying it all, and there are usually speed penalties the more complex the key session is and some of it could be optimized in workflow.

But in regards to export itself. The fastest way I know how is using a loader and saver nodes in Fusion page, avoiding resolve all together. Use a loader node in Fusion page to load up your footage, do you key process, and use at the end saver node to save it to disk as image sequence. Default is EXR, but you can also change it to jpeg or png if you change the extension of the file name in saver node.

Another thing that might speed things up, quite a bit at least for me, is to do your key, set up saver node, and before you go to menu Fusion: Render all Savers to render it. Save your project, close resolve. Open back up and don't preview the saver node or anything, live the viewer blank and just go to Fusion menu, Render all savers. And let it render. I don't know why, but for me this reduced render time by crazy amount compared to going via media out and via deliver page. Give that a try.

For simple keying process, you can also try to do it from color page, directly using keyer there. But if you work in Fusion, try saver and loader nodes and at least for me on windows, closing the resolve and opening it before rendering saver node, with no preview speeds things up quite a bit. I went on one comp from 7:33 h to 25 min.

The client hasn't given me the exact specs (it's a madhouse on their end over basic stuff) so I was basically copying the format we've been shooting it on, which is 4k 16x9 ProRes 422 HQ. They do want QT and that's what we've been using so I wouldn't veer from that.

Regarding the loading/saving nodes, I'm unfamiliar with those nodes and how to work'em. I basically started to learn Fusion for this project and my compositing knowledge isn't the biggest but for this project, it tolerates basic (so far). The lighting is consistent and pretty good so the key doesn't take a whole lot of work but it's a fluid situation
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KrunoSmithy

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Re: Alpha Matte exporting issue

PostTue May 21, 2024 10:29 am

CapitalF wrote: The client hasn't given me the exact specs (it's a madhouse on their end over basic stuff) so I was basically copying the format we've been shooting it on, which is 4k 16x9 ProRes 422 HQ. They do want QT and that's what we've been using so I wouldn't veer from that.


I see. Well, if that is what they want. Give them what they want. :)

CapitalF wrote:Regarding the loading/saving nodes, I'm unfamiliar with those nodes and how to work'em. I basically started to learn Fusion for this project and my compositing knowledge isn't the biggest but for this project, it tolerates basic (so far). The lighting is consistent and pretty good so the key doesn't take a whole lot of work but it's a fluid situation


Here are few tutorials to get you started if you are interested. Simply loader as the name suggests is used to load footage or images or anything in the Fusion page, and saver node as the name suggest is used to export them. In Fusion Resolve, you can only export as image sequence, but its fast, so you can always convert image sequence to any other format really quickly once the export is done.

FusionQuickStart 003 - Loader and Saver



Fusion Savers and Loaders to improve performance - Make Life Better - Davinci Resolve Fusion




Loader and Saver Nodes in DaVinci Resolve



For simple keying in Color Page, check out the so called 3D qualifier or keyer. Its quite powerful and comes with lot of options to despite and refine the matt.

Sometimes its quick enough so you don't need fusion page. As for Fusion and what I wrote about speed, I'm still testing it, but for me regardless if I open or close resolve, saver/loader workflow is faster than going trough mediaout to deliver page. So give it a try if you need fusion workflow.
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CapitalF

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Re: Alpha Matte exporting issue

PostTue May 21, 2024 5:53 pm

KrunoSmithy wrote:
CapitalF wrote: The client hasn't given me the exact specs (it's a madhouse on their end over basic stuff) so I was basically copying the format we've been shooting it on, which is 4k 16x9 ProRes 422 HQ. They do want QT and that's what we've been using so I wouldn't veer from that.


I see. Well, if that is what they want. Give them what they want. :)

CapitalF wrote:Regarding the loading/saving nodes, I'm unfamiliar with those nodes and how to work'em. I basically started to learn Fusion for this project and my compositing knowledge isn't the biggest but for this project, it tolerates basic (so far). The lighting is consistent and pretty good so the key doesn't take a whole lot of work but it's a fluid situation


Here are few tutorials to get you started if you are interested. Simply loader as the name suggests is used to load footage or images or anything in the Fusion page, and saver node as the name suggest is used to export them. In Fusion Resolve, you can only export as image sequence, but its fast, so you can always convert image sequence to any other format really quickly once the export is done.

FusionQuickStart 003 - Loader and Saver



Fusion Savers and Loaders to improve performance - Make Life Better - Davinci Resolve Fusion




Loader and Saver Nodes in DaVinci Resolve



For simple keying in Color Page, check out the so called 3D qualifier or keyer. Its quite powerful and comes with lot of options to despite and refine the matt.

Sometimes its quick enough so you don't need fusion page. As for Fusion and what I wrote about speed, I'm still testing it, but for me regardless if I open or close resolve, saver/loader workflow is faster than going trough mediaout to deliver page. So give it a try if you need fusion workflow.


Thanks for the tutorials and I'll check them out! One thing I realized last night was that a big reason for the ginormous time suck is because I was using the Noise Reduction plug in. For keying, I've been using the Delta Keyer and for this export, I used Noise Reduction first. The lighting is good enough that the keyer gets me most of the way there and in alpha matte, I'm honestly not sure if the noise reduction actually made much of a difference. When I did a test export of a clip with and without NR, it was 10x faster. So count me in for dumb ideas :lol: . On a movie or tv show where you actually are giving it a background, I'll likely keep it but for this specific client, I might be able to get away without it
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KrunoSmithy

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Re: Alpha Matte exporting issue

PostTue May 21, 2024 7:06 pm

CapitalF wrote:Thanks for the tutorials and I'll check them out! One thing I realized last night was that a big reason for the ginormous time suck is because I was using the Noise Reduction plug in. For keying, I've been using the Delta Keyer and for this export, I used Noise Reduction first. The lighting is good enough that the keyer gets me most of the way there and in alpha matte, I'm honestly not sure if the noise reduction actually made much of a difference. When I did a test export of a clip with and without NR, it was 10x faster. So count me in for dumb ideas :lol: . On a movie or tv show where you actually are giving it a background, I'll likely keep it but for this specific client, I might be able to get away without it


Ah, yeah, noise reduction can be really expensive on the resources, so if you can avoid it, best to not use it, but if you have to, maybe its worth it in two passes. One for noise reduction and one for the rest of it. Worth experiment with it, for me it makes fore smoother work, when I need noise reduction and heavy processing of other effects.

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