Is there a minimum supported framerate for webcams?

I have a Logitech C930e set up as a second web cam, and I use it only to check on my print every now and then. I want a high resolution image, but I don't need real video streaming, so I've done this:

camera_usb_options="-r 1920x1080 -f 1 -d /dev/video1"

However, when I look at the video feed in Octoprint, it's quite ovbious that it's running at faster than 1FPS. I'd say it's in the 5FPS range, at least.

Is it possible that the camera is not capable of such a slow framerate? Or is the driver ignoring the -f parameter?

Webcams typically support a fixed range of resolution/framerate/compression settings.

Ah, I was doing the wrong google searches. I searched for "supported framerates" and discovered this command:

v4l2-ctl -d /dev/video1 --list-formats-ext

Which gives me:

ioctl: VIDIOC_ENUM_FMT
	Index       : 0
	Type        : Video Capture
	Pixel Format: 'YUYV'
	Name        : YUYV 4:2:2
		Size: Discrete 640x480
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 160x120
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 176x144
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 320x180
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 320x240
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 352x288
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 424x240
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 480x270
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 640x360
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 800x448
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 800x600
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 848x480
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 960x540
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1024x576
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1280x720
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1600x896
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1920x1080
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 2304x1296
			Interval: Discrete 0.500s (2.000 fps)
		Size: Discrete 2304x1536
			Interval: Discrete 0.500s (2.000 fps)

	Index       : 1
	Type        : Video Capture
	Pixel Format: 'MJPG' (compressed)
	Name        : Motion-JPEG
		Size: Discrete 640x480
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 160x120
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 176x144
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 320x180
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 320x240
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 352x288
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 424x240
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 480x270
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 640x360
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 800x448
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 800x600
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 848x480
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 960x540
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1024x576
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1280x720
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1600x896
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)
		Size: Discrete 1920x1080
			Interval: Discrete 0.033s (30.000 fps)
			Interval: Discrete 0.042s (24.000 fps)
			Interval: Discrete 0.050s (20.000 fps)
			Interval: Discrete 0.067s (15.000 fps)
			Interval: Discrete 0.100s (10.000 fps)
			Interval: Discrete 0.133s (7.500 fps)
			Interval: Discrete 0.200s (5.000 fps)

So what I really want to use is this mode:

	Size: Discrete 2304x1536
		Interval: Discrete 0.500s (2.000 fps)

But this is listed under YUYV, which from I've read, uses significantly more CPU, which is the opposite of what I want.

You definitely want an MJPEG mode. Your 5 frames per second guestimate in your OP seems to be spot on.

When you set up your action cam, you can choose different resolutions and frame rates.

I know, that's what the -r and -f options are for:

camera_usb_options="-r 1920x1080 -f 1 -d /dev/video1"