Re: EXR B44A Usage

Hi Chad,

I'm afraid I only have an unhelpful answer for you: it's best to
test and work out what works best for you.

I reckon the five important metrics in picking a compression
scheme are:

- Write time

- Read time

- File size on disk

- Quality (if using a lossy compression scheme)

- Compatibility with other tools

Compatibility could be an issue for the DreamWorks schemes, DWAA
and DWAB, as it was introduced in OpenEXR-2.2.0 and may not be
supported in all your tools yet. The other metrics depend on the
kind of images you are creating, your software, and your system
setup. Compression schemes behave differently depending on the
image content and the rendering algorithm. Also, how you choose to
trade off time against storage space and image quality is really
up to you, so it's hard for anyone else to give a definitive
answer.

Given that, I'd suggest running your own tests to decide. You
might try all the schemes with exactly the same image sequence and
compositing setup, measuring the total time it takes to render the
images, the compositing time, and the file size. Beware that
timing tends to be quite variable for all sorts of incidental
reasons that may not be anything to do with the compression
scheme. For lossy compression, you could check the final images
look OK to you compared to a lossless compression approach (e.g.
ZIP).

Personally I'd avoid lossy compression on images that will be
further processed unless there's a clear win elsewhere that's
important to you. I'm guessing that "Lossy 16-bit float, in blocks
of 16 scan lines" is the "B44" scheme. "B44A" may well be a better
choice than B44, but it would be worth running tests of all
options anyway.

Peter

On 29/09/16 03:00, Chad Ashley wrote:

Hello,

This is my first posting to this list, so good morning
everyone! I had a question: When should one use the B44A
compression?

I am a 3D artist rendering primarily out of Arnold and I
normally use "Lossy 16-bit float, in blocks of 16 scan lines"
compression. Should I look to use the B44A compression
instead? What are the upsides and downsides (if any)? Or,
should I be using a completely different compression?

3D App: C4D

Renderer: Arnold

Compositor: Fusion, After Effects

Thank You,

-chad

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