Graphics pipeline

Emilio Guijarro

Other Parts Discussed in Thread: AM3715

Hi,

I'm trying to overlay simple OSD graphics on top of my video stream, using the V4L streaming interface on the Sitara AM3715 processor.

Is there any good example (simple, little or no dependencies) out there on how to do this using V4L? So far I've tried to identify which video device (/dev/video*) is responsible for this, without any luck.

Please help,

Emilio.

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi Emilio,

I will ask the factory team what support there is available for this.

0 Emilio Guijarro over 10 years ago in reply to Biser Gatchev-XID

Intellectual 410 points

Hi Biser,

thanks for your support.

Emilio.

0 jelliott over 10 years ago

Expert 1510 points

Hi Emilio,

There are a couple of ways you could do this.

One way is to use use Qt; there is an example for AM437x that demonstrates a GUI over a camera stream. The AM437x and the AM37x have the same Display Sub System, so the concepts apply equally to both. This demo works by having Qt write to the RGB framebuffer (dev/fb0) while the camera frames are put into dev/video0 and dev/video1. Then, the DSS is configured so that all 3 planes are visible and so that the RGB plane is on top of the video planes. You can't use this code as is on AM37x, but the basic ideas are very much applicable.

Another simple way to start is to just write directly to the RGB frame buffer (dev/fb0) and then use sysfs entries to configure the DSS. Here is a simple example of how to open fb0 and write to it. Once you have data in there, you can set the DSS to configure the overlays using sysfs entries.

0 Emilio Guijarro over 10 years ago in reply to jelliott

Intellectual 410 points

Hi jelliott,

I've tried the "simple way", which is our preference as we try to keep our RFS modest in size (no Qt, etc), and works fine :)

Many thanks for your help,

Emilio.

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