Sorry, I don't know off hand. I didn't work much on the code myself.
Rob
On 8/10/20 11:38 PM, Ben Meijering wrote:
Hi Rob,
Thanks for the link.
In this version I also see that m_pImgStream->setImage is invoked
in FFmpegRenderThread::run(), another thread.
2015 is a long time ago, but do you perhaps remember why this is safe ?
Thanks in advance.
Cheers,
Ben
Op ma 10 aug. 2020 om 23:03 schreef Rob Spearman
<[email protected] <mailto:[email protected]>>:
We made changes back in 2015 to fix threading issues with the osg
ffmpeg plugin. I don't think these changes ever made it into OSG.
Source repo: https://bitbucket.org/digitalis/osg-ffmpeg-plugin/
On Monday, August 10, 2020 at 3:46:32 AM UTC-7 [email protected]
<mailto:[email protected]> wrote:
Hi Robert,
Thanks for your response.
If FFmpegImageStream::publishNewFrame is invoked from a
separate thread.
Is it then somehow guaranteed that (for example)
Texture2D::apply is not using/reading from the image object,
while FFmpegImageStream::publishNewFrame is modifying it ?
Cheers,
Ben
Op vr 31 jul. 2020 om 21:24 schreef Robert Osfield
<[email protected]>:
Hi Ben,
I'm away from my dev computer so just commenting off the
top of my. FFmpegImageStream should be double buffered so
that the ffmpeg thread writing to the image will be
writing to one part of the data, while the other half is
available to be read by the graphics thread. This should
avoid threading issues.
The threading used by the ffmpeg plugin is separate from
the viewer threading so settings related to the viewer
won't be important, nor will general settings of the scene
graph.
You should be able to just add the ffmpeg genearted
imagestream to a texture, start the steam going and then
largely forget about it.
Robert.
On Friday, 31 July 2020 at 20:15:45 UTC+1
[email protected] wrote:
Hi,
I was just looking at FFmpegImageStream, I am not very
familiar with this code, but I have some questions.
It is not immediately clear to me how
FFmpegImageStream::publishNewFrame is thread safe.
It seems like the image data is set (setImage) from
the video decoder thread.
The image then uses a pointer to one of the buffers of
the video decoder (of which the contents might also
change ?).
FFmpegImageStream also doesn't seem to override
requiresUpdateCall, which I believe will result in the
texture not being dynamic (Texture2D::setImage).
Which could be used, for example in
StateSet::computeDataVariance(), to determine whether
the StateSet should be dynamic (which is needed for
multithreaded rendering).
If anyone could shed more light on this subject, it
would be very much appreciated.
Thank you.
Cheers,
Ben
--
You received this message because you are subscribed to the Google Groups
"OpenSceneGraph Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/osg-users/6e750bea-6962-0f6c-b161-7e98cbd5c0ce%40digitaliseducation.com.
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
