DDS Textures compression for optimized VRAM footprint and speed in X-Plane 11.5

[Daniel Recio]

Hi all,

We all know that the realisms and quality of this TBM900 is out of the scale when compared with most of the aircraft created for X-Plane. Unfortunately, we all know that it can become a bit heavy on requirements too.

I was checking yesterday the VRAM profiler in X-Plane while flying and I suddenly realized the HUGE footprint that our "bird" requieres in VR. I was using my Rift S (1.5 SS), and the TBM was taking almos 1.5Gb of VRAM!. This is quite a lot, even for my RTX2080 with 8Gb VRAM. I compared the numbers with a very heavy FlightFactor A320, and this "small" TBM is taking more than double the VRAM.

When checking that in detail, I think that this is something that could be easily solved before the next release (in beta now). All the textures are still in PNG format instead of the modern DDS (DirectDraw Surface).

There are lots of forum entries in X-Plane developer forums and they already have a tool for converting the textures to the right format.

https://developer.x-plane.com/docs/scenery/ddstool-manual/

Some more details about DDS textures here:

https://sites.google.com/view/xpdc/general/texture

DDS textures are optimized and faster to load, they also take a smaller footprint in VRAM, so it is a clear win.

 

Could you please take this into consideration for the next release?

Thanks in advance,

Dani

Edited November 20, 2020 by Daniel Recio

[Goran_M]

dds vs png is a bit of a confusing topic for some.  (Including me a few years ago)

Here's the deal, in basic terms.

dds textures load faster.  png files load a little slower, but not by much, because CPU's today make small work of compression algorithms.  

So here are 2 images showing dds texture size and png texture size inside X-Plane (on disk).  Pay particular attention to Fuselage_Rear.png and .dds

What do you notice?

X-Plane compresses png's.

 

Edited November 20, 2020 by Goran_M

[Daniel Recio]

Hi Goran,

Thanks a lot for answering. As you can imagine, I am not a developer myself, but I am just basing my questions in some posts from Ben Supnik (X-Plane). Some of them are from time ago, when DDS was initially introduced. Some interesting points are made in the following post.

https://developer.x-plane.com/2012/01/dds-revisited-in-x-plane-10/

"DDS is an image format that contains a compressed image.  DDS files load faster (because the image is already compressed), look better (because the image is compressed using a slower, higher quality process before sim load) and let you pick the DXT algorithm choice. (In some cases, the choice between DXT3 or DXT5 matters!)  ...

Compression is useful for more than just saving VRAM – because the amount of data needed to texture a given pixel is smaller (4 bits per pixel instead of 32) compressed textures can speed up framerate if the memory bus between the GPU and its own VRAM is congested."

I am pretty sure that you have the tools and knowledge for giving the best product, but I just was wondering if this would bring some benefit

Maybe just changing one file texture is not enough to appreciate the difference, but maybe if the whole texture set is converted... we could see some gain.

Thanks a lot for your time,

Dani 

[Goran_M]

Sure, I understand.

I did speak to Saso earlier about this, and he did say he'll look more into it, and if it proves to be much better, overall, we would look more into using dds textures.

 

[Daniel Recio]

Thanks a lot for your effors and your time!!