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/dev/video0 camera support
Posted: Thu Jan 31, 2019 9:48 am
by rvalvekar
Hello All,
I have been reading that some cameras don't have the interface as /dev/video0 , and hence have to use gstreamer as primary execution medium for cameras.
I would like to ask, is there any way we can enable /dev/video* as filepath for Camera Devices ? Is there any specific module that the Linux OS has to have inorder to work with /dev/video* support ?
I know video4linux drivers which can be used with webcam, but i would like to know if it can be also used in CSI Cameras.
Thanks,
BR.
Re: /dev/video0 camera support
Posted: Thu Jan 31, 2019 1:55 pm
by pavelectric
Re: /dev/video0 camera support
Posted: Fri Feb 01, 2019 12:45 pm
by ayaromenok
I found some
limitation by using Video4Linux with CSI camera with FriendlyDesktop:
- only full resolution can be used (you will need to downscale it outside of ISP) ;
- looks like NV12 encode image arrive (to convert to RGB/BGR you will need to decode it);
I am continue to evaluate this question, so some update is possible:
PS: looks like you can't use CSI cameras with armbian/any other linux right now due to some missed kernel support
Re: /dev/video0 camera support
Posted: Fri Feb 01, 2019 1:23 pm
by rvalvekar
ayaromenok wrote:I found some
limitation by using Video4Linux with CSI camera with FriendlyDesktop:
- only full resolution can be used (you will need to downscale it outside of ISP) ;
- looks like NV12 encode image arrive (to convert to RGB/BGR you will need to decode it);
I am continue to evaluate this question, so some update is possible:
PS: looks like you can't use CSI cameras with armbian/any other linux right now due to some missed kernel support
I have had worked before with a CSI Camera and Nano T3 board, and could not use /dev/video* in opencv. I tried implementing gstreamer at one point, but its quite tedious to compile OpenCV with gstreamer support. But I am also finding a way to get support in Linux for /dev/video* with CSI Camera.
I am not sure about the encode NV12 to decode, but it might be possible to do it in OpenCV
Re: /dev/video0 camera support
Posted: Fri Feb 01, 2019 5:14 pm
by ayaromenok
rvalvekar wrote:
I am not sure about the encode NV12 to decode, but it might be possible to do it in OpenCV
It's possible, but not rational - it will take a large amount of memory and CPU/GPU computation power, while ISP (Image Signal Processor - special unit, responsible for cameras and basic image operations) would stay idle.
Re: /dev/video0 camera support
Posted: Fri Feb 01, 2019 6:43 pm
by rvalvekar
ayaromenok wrote:rvalvekar wrote:
I am not sure about the encode NV12 to decode, but it might be possible to do it in OpenCV
It's possible, but not rational - it will take a large amount of memory and CPU/GPU computation power, while ISP (Image Signal Processor - special unit, responsible for cameras and basic image operations) would stay idle.
I was researching about it and i figured that out after posting this. I am still going to dig in, if or how can we get it working /dev/video*
I dont know if all Single Board Computers are equipped with ISP.
Re: /dev/video0 camera support
Posted: Fri Feb 01, 2019 6:56 pm
by ayaromenok
rvalvekar wrote:
I dont know if all Single Board Computers are equipped with ISP.
without ISP it's impossible to grab image from Camera, connected via CSI lines
(so some chips don't have it, but Rk3399 include his own ISP). You can check Rockchip kernel 4.4 and gstreamer for details, as well as their
official info.
Re: /dev/video0 camera support
Posted: Tue Feb 05, 2019 12:35 pm
by ayaromenok
rvalvekar wrote:
I would like to ask, is there any way we can enable /dev/video* as filepath for Camera Devices ? Is there any specific module that the Linux OS has to have inorder to work with /dev/video* support ?
Right now I am playing with Armbian\their kernel(4.4.172, which have all changes for friendlyelec cameras ), so direct answer to your question - need to enable in the kernel config:
Code: Select all
CONFIG_VIDEO_ROCKCHIP_ISP1=y
CONFIG_VIDEO_ROCKCHIP_ISP_DPHY_SY=y
CONFIG_VIDEO_ROCKCHIP_CIF=y
CONFIG_VIDEO_OV4689=y
CONFIG_VIDEO_OV13850=y
(for ISP and 4M & 13M cams)