[Bf-committers] Re: Screen dump - OpenGL content

Brecht Van Lommel brechtvanlommel at pandora.be
Tue Sep 12 15:21:35 CEST 2006


I don't think event recording is a full replacement for video, most
of the times I need it is to show a new feature. And I haven't found
a fast free screen recording utility either for Mac.

I modified some async upload code I did earlier to do download
instead. It uses the pixel buffer object extension, and the idea
is described here:


It runs reasonably fast, with quicktime export being the bottleneck
by far. Most of that is in the Blender side code even, so certainly
still room for improvement. It should work with ffmpeg also, but don't
know about the speed there.

The code only records a fixed size, and doesn't correctly timestamp
the frames, etc, but anyways:



Rui Campos wrote:
> Camstudio works great under Windows, but you don't have a similar solution
> in Linux.
> You do have Wink and Istanbul, but they aren't very good solutions right now.
> Istanbul is dead slow when grabbing OpenGL and Wink crashes sometimes and
> isn't that fast either.
> I was hoping to get something faster for recording Blender under Linux as
> none of the mentioned options work for me.
> And yes, I think lukep is recoding the event system, meaning this work
> would probably be lost. But this isn't done yet, so it might worth the
> effort and if a good API for python was built it could be reused later on.
> On how slow it could be, I don't know, haven't came up with a way to play
> the events, only record them.
> On the OpenGL recording, it would be needed a good machine, yes, and
> that's why I asked for a faster way to do the screen dump as the overhead
> right now is just on the glReadPixels method call.
> My problem is that even on a Core Duo 1.83Ghz machine, neither Istanbul,
> nor Wink work fast and reliably.
>> Congrats for the new baby :)
> ? I think I missed this one !?
> Do you know something I don't ....
> Cheerz,
>     -- Rui --
> ----- Original Message -----
>> Rui Campos wrote:
>>> Hi all,
>>> My current knowledge only allows me to do this type of recording.
>>> I'm already able to record most of the keys / mouse events on a stack, but
>>> my problem is playing them back, moving the mouse and pressing the keys
> again, if I could do this I would write a simple Python API and script
> for
>>> it.
>>> The problem is that I didn't find a nice way to move the mouse to a given
>>> location and issue keyboard commands. If anyone can help me I rather do
> this instead.
>>> -- Rui --
>> Just a couple of questions to take with a grain of salt since they come
> from a man who knows just enough to be dangerous ;)  :
>> In the case that you go for and event stack :
>>    -isn't the event system being recoded by Lukep right now ? If so how
>> much of your efforts would soon become obsolete if any ?
>>    -replaying the events, without any undo stack, can take a loog time
>> can't it ? Much longer than a video sequence.
>> In the case you go for OpenGL recording :
>>    -how much overhead will this add to Blender ? Won't it slow down to a
>> crawl on most machines ?
>>  A possible solution to this would be to suspend the recording while
>> Blender is working hard and blocking the user from accessing the UI anyway.
>> Now can you tell me what is your motivation ?
>> Until now I just couldn't shake off the impression that yours is a
> solution in quest for a problem.
>> I make a lot of tutorial for the company where I work, some are about
> Blender, and I use Camstudio with its lossless codec (less overhead at
> recording time) with litterally perfect ease.
>> Many other solutions exist so why ?
>> If nothing else your answers will make my reading this thread a lot more
> comfortable.
>> Congrats for the new baby :)
>> Jean
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