Efficiency of simple GPU matrix readback

strontiumDog's icon

Hello

I have the patch below, which I've obviously hashed together from bits of tutorials.

I've noticed that with a 1sec movie loaded into both sides, the slab/videoplane works fine, until I want to record my filtration.

When I connect the slab to the matrix in order to record the two movies filtered together, the result in the window visibly suffers. It's only slight, but noticeable and I have a great deal more I want to do, and then record.

I'm on a mac pro with 8 cores and 16gb of memory. I shouldn't be troubled by this but I am and it means that there is something with the patch/max performance setup which I'm not doing, but as I cannot record on the GPU, it seems as though as soon as I drag the result of a GPU op back to record, performance goes down.

Max Patch
Copy patch and select New From Clipboard in Max.

Just had a thought as I typed this which I'll check tomorrow - it's not cos I'm not using uyvy on the matrix is it? Or maybe because I'm using a window/render/videoplane? In the latter would I get any performance benefit by flying blind and checking the result?.

Rob Ramirez's icon

if you want to record the output of your opengl scene you should be using jit.gl.asyncread.
imho, a better solution is a screengrab software like iShowU or Fraps.

efe's icon

or use an external device.

strontiumDog's icon

Robert thx v much for your post. I'd not seen asyncread in the module a-z in the manual cos it's not there... works a treat. although like you, i think ishowu is prob the way forward - thanks for that too - i'd not heard of it before, i was using a much worse equivalent.

efe - i'm interested to know what h/w you'd had in mind.

thanks v much!

strontiumDog's icon

Hello - I've put a patch together and noticed the result of the asyncread -> record produces a movie running at twice the speed - why is this?

geoscle's icon

Got the same problem as strontiumDog with jit.gl.asyncread, the .mov is a little bit faster than the original so it's impossibile to sync with the audio track.

Codec: photojpg
fps: 25
resolution: 720 480

any issue