Render with two Blender processes on same computer: compression issues? #39521

New Issue

Colin · 2014-03-30T21:22:52+02:00

Colin commented

2014-03-30 21:22:52 +02:00

System Information
Win7
Nvidia Quatro FX 4600
ATI Radeon 3000

Blender Version
Not sure if it ever worked, but just tried 2.7

Short description of error
Open two copies of blender on same pc, only grabs render frame from one program or none

Exact steps for others to reproduce the error
I am trying to render a stereoscopic animation, I don't know if blender can do this (game engine can do stereo) in one pass..
Basically I have two cameras and a short animation, rather than waiting for left to render, I opened blender again on same pc and started rendering the right camera at same time.

I got a garbled mess with mpeg options, dropped/black frames for both files.
Then I tried PNG and noticed I was getting the same image for left and right (but individual manual shots were correct, render button, not animate) and then I started getting black frames while I was checking image output.

I think I even tried one blender copy on cpu and the other on cuda and still nothing useful.

If screen/vid card makes a difference, one blender window is on nvidia and the other is on the ATI card.

Thanks for your time! Love this program!

I'm not sure if this ever worked.. (I think I did it before though on an older version), but it would be great if it did

**System Information** Win7 Nvidia Quatro FX 4600 ATI Radeon 3000 **Blender Version** Not sure if it ever worked, but just tried 2.7 **Short description of error** Open two copies of blender on same pc, only grabs render frame from one program or none **Exact steps for others to reproduce the error** I am trying to render a stereoscopic animation, I don't know if blender can do this (game engine can do stereo) in one pass.. Basically I have two cameras and a short animation, rather than waiting for left to render, I opened blender again on same pc and started rendering the right camera at same time. I got a garbled mess with mpeg options, dropped/black frames for both files. Then I tried PNG and noticed I was getting the same image for left and right (but individual manual shots were correct, render button, not animate) and then I started getting black frames while I was checking image output. I think I even tried one blender copy on cpu and the other on cuda and still nothing useful. If screen/vid card makes a difference, one blender window is on nvidia and the other is on the ATI card. Thanks for your time! Love this program! I'm not sure if this ever worked.. (I *think* I did it before though on an older version), but it would be great if it did

Colin commented

2014-03-30 21:22:52 +02:00

Changed status to: 'Open'

Colin commented

2014-03-30 21:22:52 +02:00

Added subscriber: @DerBen-2

Bastien Montagne commented

2014-03-30 22:39:51 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2014-03-30 22:39:51 +02:00

Well, if you render to the same (video/png) file from two different processes, no wonder why it fails… If you render in two different files, I do not see why it would break.

Please attach small .blend file demonstrating the issue, with precise steps to reproduce it.

Well, if you render to the same (video/png) file from two different processes, no wonder why it fails… If you render in two different files, I do not see why it would break. Please attach small .blend file demonstrating the issue, with precise steps to reproduce it.

Colin commented

2014-03-30 23:42:21 +02:00

HauntedHouse19BUG.blend
Nope, I render to left and right files for videos or sequences. Basically I have a left and right video, and in turn a left and right image sequence rendered.

Left.mpg and Right.mpg

or

left001.png
right001.png
left002.png
right002.png

Anyway, there's cameraL and cameraR

Open blender twice, load the attached file in both.

select cameraL in one and cameraR in the other,
CTRL+num0 on both windows

you can try PNG or mpeg

hit animate and watch the output. (you might have to set an output folder)
The files left and right should not be identical, but off by a bit.

[HauntedHouse19BUG.blend](https://archive.blender.org/developer/F83509/HauntedHouse19BUG.blend) Nope, I render to left and right files for videos or sequences. Basically I have a left and right video, and in turn a left and right image sequence rendered. Left.mpg and Right.mpg or left001.png right001.png left002.png right002.png Anyway, there's cameraL and cameraR Open blender twice, load the attached file in both. select cameraL in one and cameraR in the other, CTRL+num0 on both windows you can try PNG or mpeg hit animate and watch the output. (you might have to set an output folder) The files left and right should not be identical, but off by a bit.

Colin commented

2014-03-30 23:44:07 +02:00

Adjust Output folder and name as per the camera!

Bastien Montagne changed title from ~~Rendering technicality~~ to Render with two Blender processes on same computer: compression issues?

2014-03-31 08:38:40 +02:00

Bastien Montagne commented

2014-03-31 08:41:05 +02:00

OK, I can confirm the issue… I really wonder what happens here, sometimes you even get pictures which mix both left and right views!

Bastien Montagne self-assigned this 2014-03-31 08:45:22 +02:00

Bastien Montagne commented

2014-03-31 08:45:22 +02:00

Ah, in fact, think I know what’s happening here… You are using full buffers for OSA, which means Blender has to save them in temp files. Obviously, it generates same names for both right and left cam… Will see how to add some kind of "salt" to those, using the PID or timestamp e.g. maybe?