SOS – After Effects Corrupted PNG Render Problem

[Chris Dortch]

I inserted a Hitachi DeskStar 7200RPM hard drive into the hot swappable drive bay to write my files to two weeks ago; however, my problem started a week after doing this. Thanks for the HDV tip, but my project has no HDV footage. I have noticed this problem while rendering with Nucleo Pro, but the problem persists even if I turn Nucleo pro off. The purge tip may fix the problem if rendering with AE. I will just have to give it a try. Is there a way to set Nucleo Pro to purge every so often? I am not a multi-processing expert, but it seems like every X number of frames, one background instances of AE will crash before it finishes the frame it was working on.

[Chris Wright]

PNG only supports 16bpc. Use EXR if you want 32bpc float. Are you premultiplied or straight alpha?
PNG is truecolor up to 48-bit compared to 8-bit 256-color.
Each PNG image will take up like 10-13mb.
Your hard drive could be the culprit. Rendered multiple frames simultaneously might be on.

[Chris Dortch]

Thanks for the notes about color depth. I do not need the output to have 32bpc attributes. I am working in Float only to capture the look of Float into the 8bpc premultiplied output. Keri Matthews of Gridiron software sent me a message saying:

“It looks like the problem is due to the output being png files. Png files are not threadsafe, so if generating several at a time you may run into problems…”

So I need to either turn multiprocessing off or use a “threadsafe” format if I want to avoid further multi-processing problems. Which of the following are threadsafe?
– Targa
– Tiff
– SGI
– Radiance
– Photoshop
– PICT
– Open EXR
– Electronic Image
– Cineon
Other?

[Chris Wright]

https://www.adobeforums.com/webx/.59b50368
Nucleo and multiproc can’t be on together same time.

[Chris Dortch]

You are nice to comment, but I am aware this.

[David Dubois]

I get this problem when network rendering PNG’s.
It seems to be cause by 2 machines (or instances – as in NPro) trying to write the same frame at the same time.

From what I can gather, a PNG file is not written UNTIL the file has been partially rendered. JPEGS etc seem to write a holding 0k file so that other machines cannot pick up that same frame to render.

Try rendering as TGA’s with NLE compression (Lossless compression – works like a .zip file).
That worked for us. Or turn off NPro whilst rendering.

Hope that helps.
Dave

Currently working on ‘Lookin’ For Lucky’ – Feature Film for Albino Injun Productions.

http://www.lookinforlucky.co.uk

[Chris Wright]

You are very smart using Targas. They are the most stable of all. Even TIFF has overflow internal buffer problems. Targa puts all its data in a fixed location with minimal code, and anytime you have minimal code, you have minimal problems.:D

[Chris Wright]

I thought I should add, 16-bits per channel, which gives you 48 bits per pixel is not available in all image sequences including targa which has only 10.67 bits per pixel at max 32bpc. What’s the precision of 10.6 to 16 bits/pixel you ask? Almost none unless you’re Disney making master film archives or re-rendering 20x same clip in a row. And now here are the famous confusing color tutorials.

https://www.cambridgeincolour.com/tutorials/posterization.htm
https://www.cambridgeincolour.com/tutorials/color-space-conversion.htm
https://www.cambridgeincolour.com/tutorials/sRGB-AdobeRGB1998.htm

[Chris Wright]

I thought I should add, 16-bits per channel, which gives you 48 bits per pixel is not available in all image sequences including targa which has only 10.67 bits per pixel at max 32bpc. What’s the precision of 10.6 to 16 bits/pixel you ask? Almost none unless you’re Disney making master film archives or re-rendering 20x same clip in a row. And now here are the famous confusing color tutorials.

https://www.cambridgeincolour.com/tutorials/posterization.htm
https://www.cambridgeincolour.com/tutorials/color-space-conversion.htm
https://www.cambridgeincolour.com/tutorials/sRGB-AdobeRGB1998.htm