nvhost-vic v4l application

Autonomous Machines Jetson & Embedded Systems Jetson TX2
#1

I am integrating the VIC into my existing V4L application. I have opened the descritor, and set up a capture plane (with V4L_MEMORY_USERPTR), and an output plane (with V4L_MEMORY_DMABUF).

If I map my dmabufs going in, i get data; the pipeline seems to be working (I am able to DQ capture buffers), but my capture buffers are all unmodified (they contain the same data that they did when they were queued).

My input DMABUFS are coming from libargus. they’re V4L2_PIX_FMT_YUV420M and V4L2_NV_BUFFER_LAYOUT_BLOCKLINEAR. I’m trying to convert to V4L2_PIX_FMT_ABGR32 and V4L2_NV_BUFFER_LAYOUT_PITCH

Is there some step i may be missing? how can I debug this?

#2

Hi wdouglass,
Please refer to the sample tegra_multimedia_api\samples\07_video_convert

You may also try to set capture_plane V4L2_MEMORY_MMAP.

#3

Ok, i’ve got this figured out. In the past, when I used V4L2_MEMORY_MMAP, i would use mmap(2) to map the memory into my address space directly, then use glTexImage to upload my texture to the GPU for display.

Turns out with the NVIDIA v4l drivers, i need to first export the memory to a DMAbuf (using VIDIOC_EXPBUF), then use glEGLImageTargetTexture2DOES to upload the texture to the GPU. It’s a little different then what I’m used to, but it works.

Thanks for the hint!

#4