Migrate YUY2 conversion and sending to NDI stack to a separate thread when called with --threaded. Requires using c++14 (for make_unique).

Signed-off-by: Charles Steinkuehler [email protected]

I have received the Hornettek HDMI to USB 3.0 adapter, but testing results in very poor video performance. This is not dropped frames, but bursty/choppy video. The system is under fairly low load, with htop reporting about 30-35% CPU usage.

The issue appears to be caused by V4L2, as when I instrument the code to report when it receives a frame (just print a "." and fflush()) I see the issue even when I entirely disable the call to process_image.

Are there any tweaks required to get good V4L2 input performance (eg: config.txt modifications or similar)?

P.S. Feel free to email me directly (see Signed-off-by: in my commit) if you'd prefer.

I'm looking to set up a couple of (relatively) cheap NDI cameras in my studio for different angles, and wanted to know if there is any unusual settings I would need to know about to make it work with the HQ Camera.

So I've come up with a work around for grabbing a mjpeg USB type deice using the v4l2 lookback

//install and enable sudo apt install v4l2loopback-dkms sudo modprobe v4l2loopback

//find which dev it is. v4l2-ctl --list-devices

//generate the loopback; note the -i /dev and output /dev for output will be different for different machines ffmpeg -f v4l2 -video_size 1920x1080 -input_format mjpeg -i /dev/video2 -pix_fmt yuyv422 -f v4l2 /dev/video4

//stream to ndi v4l2ndi -d /dev/video4 -f

So I've come up with a work around for grabbing the display output on x11 based systems using the v4l2 lookback

//install and enable sudo apt install v4l2loopback-dkms sudo modprobe v4l2loopback

//find which dev it is. v4l2-ctl --list-devices

//generate the loopback; note the -i for input and /dev for output will be different for different machines ffmpeg -video_size 1920x1080 -f x11grab -framerate 15 -i :1.0 -c:v rawvideo -pix_fmt yuyv422 -f v4l2 /dev/video4

//stream to ndi v4l2ndi -d /dev/video4 -f

So this works for me, the gotcha was the pix_fmt, and getting it to the YUYV that v4l2ndi required. Without which would give the following error; v4l2ndi -d /dev/video4 -f Path: /dev/video4 Driver: v4l2 loopback /dev/video4 support output /dev/video4 support capture /dev/video4 support read/write /dev/video4 support streaming Current pixel format: BGR4 Current frame width: 1920 Current frame height: 1080 Setting pixel format to: YUYV Cannot set format VIDIOC_S_FMT error 22, Invalid argument\n

If you have any ideas how we could add this without the need for the loopback that would be great, happy to jump into code or test if you can point me where to start?

So been testing this today and ran into a problem that's not v4l2ndi's fault but something to be aware of with multiple USB video interfaces.

https://stackoverflow.com/questions/11394712/libv4l2-error-turning-on-stream-no-space-left-on-device

Sums up the issue and moving devices over multiple root hubs worked for me.