Wish: faster save of PNG per multi core support

[Micha]

Hi,

saving large images is a slow process, most if several layers needs to be saved. So I ask me couldn't possible that all cores are used to compress the PNG? And/or maybe all render elements could be parallel compress.

Best-
Micha

[yavor.rubenov]

Hello,

Since you posted in the Max wish list forum - I'll answer first for Max
In V-Ray for 3ds Max we use the native 3ds Max system for writing output images - that way images can be saved to any format supported in Max. Few years ago we tried exactly what you propose - when saving multiple channels to use separate thread for each channel. Unfortunately it turned out that there are stability issues and the Max output system didn't handle multithreaded writing - some formats worked some formats produced broken images. So in the end we decided to go back to single threaded saving..

If you are asking for other V-Ray integrations - which one ?

Best regards,
Yavor

[Micha]

Hi Yavor,

I'm using V-Ray for Rhino Next and thought saving from the frame buffer is independent from the use integration. Interesting, that it is not so.
Saving the output needs dependent from the resolution a half minute or much longer. So, should I better ask at the Rhino forum?

Best regards,
Micha

[Peter.Chaushev]

Hello, Micha,

In the case of V-Ray for Rhino Yavor's explanation also applies. There's no multi-thread support to image file writing in V-Ray Next for Rhino.
A request will be logged. It will affect, however, only the VFB "Save channel" button functionality.

Kind regards,
Peter

[Micha]

Hi Peter.Chaushev

a much faster VFB saving would be great. Maybe parallel saving channels is possible too.

Thanks,
Micha

[Micha]

I have the impression there is something wrong - at VfR2 it needs a few seconds to save a 3600x2400 rendering (mat ID, final pass) and at VfR4 it needs approx. 40s for the little task. Could be great if someone could check it. ( Peter.Chaushev )

[Peter.Chaushev]

I have the impression there is something wrong - at VfR2 it needs a few seconds to save a 3600x2400 rendering (mat ID, final pass) and at VfR4 it needs approx. 40s for the little task. Could be great if someone could check it. ( Peter.Chaushev )

We were not able to reproduce the described slowdown, nor any noticeable difference in the save time between v2.0 and v4.02. If this behavior is reproducible on your side only with some particular projects, please send one of them over at support@chaosgroup.com for further investigation. If it is not scene-specific, then we can offer remote assistance to track down the issue at hand.

Kind regards,
Peter

[Micha]

I have no VfR2 running at the moment, but today I use JPG instead PNG for "save all channels" and the save time was approx. 20s vs. 5s (PNG vs. JPG) for a small rendering. It would be great, if the PNG save times could be in the same range like the JPG save times. Todays computers are super fast and it's a miracle that the save time of the PNG is so long.

[Micha]

I saved a large rendering (6000x3000) to PNG and it needs approx. 49s. I opend the image at PS, changed something and saved it again - nearly the same file size but saved in approx. 7s. It looks like at PS is done something magic, since the PNG mode was "fast and big" but the file size wasn't big.

The long save times are a problem also for animations. So, if RGB, denoiser, effects are saved than the save time starts to be the same like the render time. This means a frame needs the doubled time. This is a lot.

An other example - if I render a pano at 10000x5000 and RGB, denoiser, effects than several minutes are needed to save the output.

Please dear Chaosgroup team, please Peter.Chaushev , try to find a solution for this issue. It could be great to get speed and times of PS.

[kosso_olli]

An other example - if I render a pano at 10000x5000 and RGB, denoiser, effects than several minutes are needed to save the output.

These are resolutions we are dealing with every day, and depending on the number of channels (around 12 is common these days), saving can easily take up to 20-25 minutes for EXR file format. We often have cases where the actual rendering is quicker than the saving... If there are ways to improve this, that be very welcome!

[Micha]

Peter.Chaushev I come across this topic and I have seen that you ask for an example. I found a easy way to replicate it - open a large JPG like 10.000x5.000 at the frame buffer and save it - ~15s at VfR2 and ~55s at VfR4 (latest release). Important seems to be to use a custom curve. Without curve VfR4 is not so slow.

I hope this helps to find the reason for the slow down. General it could be nice if the frame buffer could save images like PS - super fast and small PNG sizes, also if "small and big" is chosen.