Re: [eq-dev] Decoupled Source / Output Channel frame rate

[Stefan Eilemann]

Hi,

On 3. May 2013, at 3:53, Alessandro Febretti [via Software] <ml-node+s171...@n2.nabble.com> wrote:

> I would like to know if it is possible in Equalizer to have an source channel generate frames at a framerate different wrt. the output (i.e. render window) channel.
>
> The use case is a distributed volume renderer generating frames at a framerate lower than the framerate of the output channels. The output channels would ideally draw faster and for instance overlay a 2D ui on top of the volume renderer output. I hope this makes sense.

To summarize my understanding: the 3D content update is slower and decoupled from the 2D UI.

Conceptually this is hard to map into Equalizer directly, as there is no concept of what you want to do. It requires some threads to run async (on different GPUs?). As soon you want to run both on the same GPU, you're in trouble anyways.

There is the DPlex 'period/phase' setting, although I don't think they'll help in this case.


> On a somewhat related note: is it possible for two separate instances of equalizer (one rnning on a render cluster, one on a display cluster) to exchange frames?

You can always implement this yourself at the Collage level. We might need to refactor the image compression/sending logic to make it usable outside of Eq.

I guess the best would be to open a ticket, describe your requirements in detail and we'll iterate on it.


Cheers,

Stefan.





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[Stefan Eilemann]

On 18. May 2013, at 21:19, Alessandro Febretti [via Software] <ml-node+s171...@n2.nabble.com> wrote:

> Thanks for your help Stefan,
>
> I may implement this myself using Collage and a few classes from Equalizer. As a brief hint, can you point me to what classes in Equalizer deal with grabbing the frame buffer

Image::start/finishReadback, used by the Channel::frameReadback and the async readback finish thread's Channel::_finishReadback()


> and turn it into a byte stream?

...and now it gets ugly. The code is in Channel::_transmitImage, but should be refactored into an operator <</>> (DataO/IStream&, Image&) to be reusable. Most of the complications are due to the handling of compressed/noncompressed image data and the serialization of the individual compressed chunks.


HTH,

Stefan.
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http://www.eyescale.ch
https://github.com/Eyescale/
http://www.linkedin.com/in/eilemann








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