How to access framebuffer on linux armle platform?
We would like to access the framebuffer for further processing. We'd also need access to the alpha channel.
Currently we're experimenting with two sb engines, running on an i.MX8MM:
- We could just use /dev/fb0
- However the alpha channel seems to be a constant 255 for every pixel
- Also, rendering is pretty slow
- Image is drawn with transparency when using the -oscreen_mgr,overlay option for sbengine
- ..but the framebuffer can't be accessed that easily
Is it possible for storyboard to use an external buffer to render into?
Apologies for the delay in response.
Since NXP has released the i.MX8 series of hardware the standard fbdev interface has been deprecated and the framebuffer is actually a virtual one (likely with a DRM backend) That change explains why the framebuffer may not be behaving as it did on hardware that supports fbdev (i.MX6 for example).
Going forward Linux systems will be migrating to Wayland screen management. Many system images come pre-configured with the Weston compositor, however, Weston does not give you direct management of screens. So you will either need to manage the windows yourself or explore the external buffer options that you mentioned.
Storyboard can integrate external content into our "external buffer" render extension. This section of the documentation describes it at a high level.
Our section on supporting multimedia explains how you might integrate with Gstreamer and our external buffer.
Hopefully, this helps answer your question.
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