"Consumers" fluctuating between 1 and 2, causing stutters

[Hubro]

When not consuming the fake webcam, "Consumers" seems to fluctuate between 0 and 1:

Consumers: 1
No consumers remaining, paused
Consumers: 1
No consumers remaining, paused
Consumers: 1
No consumers remaining, paused
Consumers: 1
No consumers remaining, paused

These 8 lines of output are printed approximately every 3 seconds.

When I do consume the webcam, for example via Chrome, the output changes to:

Consumers: 2
Consumers: 1
Consumers: 2
Consumers: 1
Consumers: 2
Consumers: 1
Consumers: 2
Consumers: 1

These 8 lines of output are again printed approximately every 3 seconds. Right before they are printed, the fake webcam output freezes for almost half a second. The end result is that every 3 seconds, the webcam stutters.

During those 3 seconds though, I'm getting a completely solid, stable 30 FPS and the camera is looking great!

Since I can't see that anybody else has this problem, I assume there's something weird with my setup. How can I start troubleshooting?

[Hubro]

Alright, I found the culprit. As long as Discord is open in the background, it will consume the fake exactly 4 times in an instant, approximately every 3 seconds, which makes the camera stutter. Very weird... Anyone else have the same issue? Any suggestions for a workaround?

[fangfufu]

The --no-ondemand flag?

[fangfufu]

This (#162) would have improved the issue, but it causes the script to crash.

[Hubro]

The --no-ondemand flag?

Right, I was planning to try that. That does indeed solve the problem, but it also causes too much CPU activity to keep this script always running.

I guess I'll wrap this up into a script I can run while doing video meeting.

Unrelated - I just rebooted my machine, and for some reason I'm now capped to exactly 15 FPS no matter the FPS value I choose. This is the exact same command I was running earlier:

python3 fake.py --no-ondemand -W 1920 -H 1080 -F 30 --no-background --background-blur 20 --no-foreground -w /dev/video0 -v /dev/video2

Output:

INFO: Created TensorFlow Lite XNNPACK delegate for CPU.
Real camera original values are set as: 640x480 with 30 FPS and video codec 1448695129
Real camera new values are set as: 1920x1080 with 30 FPS and video codec 1196444237
Running...
Please CTRL-C to pause and reload the background / foreground images
Please CTRL-\ to exit
FPS:  14.98

Before I rebooted, I was getting 30 FPS with fairly low CPU usage. It seems to be capped to 15 FPS for some reason. Any ideas?

[fangfufu]

Can you get your Discord to use another webcam? I am a bit busy right now. I don't have time to move inotify to another thread.

Why don't you run the benchmark script to see if it is webcam problem? Have a look at #160 It could be lighting or some other issue that causes the real webcam to lock up at 15 FPS.

[Hubro]

It could be lighting or some other issue that causes the real webcam to lock up at 15 FPS.

That makes a lot of sense, I'll keep that in mind.

On an unrelated topic, I made a script to automate setting up the loopback interface and start fake.py:

#!/bin/bash

FAKER_PATH="$HOME/src/github/fangfufu/Linux-Fake-Background-Webcam"

# Print an informational status message to the user
function inform() {
    if [[ -t 1 ]]; then
        echo -e "\e[34;1m ==> $*\e[0m"
    else
        echo " ==> $*"
    fi
}

# Print an error message
function error() {
    if [[ -t 1 ]]; then
        echo -e "\e[31;1m ==> $*\e[0m" >&2
    else
        echo " ==> $*" >&2
    fi
}

function blurred_cam_video_nr() {
    v4l2-ctl --list-devices \
        | grep -F -A1 "Blurred background virtual cam" \
        | tail -n1 \
        | tr -d '[:space:]'
}

function create_loopback_cam() {
    sudo modprobe -r v4l2loopback

    sudo modprobe v4l2loopback \
        devices=1 \
        exclusive_caps=1 \
        card_label="Blurred background virtual cam"
}

function start_fake_cam() {
    local LOOPBACK_DEVICE="$1"

    cd "$FAKER_PATH"

    exec python3 fake.py \
        --no-ondemand \
        -W 1920 -H 1080 -F 30 \
        --no-background \
        --no-foreground \
        --background-blur 30 \
        -w /dev/video0 \
        -v "$LOOPBACK_DEVICE"
}

function check_dependencies() {
    local ERROR=no

    if ! which v4l2-ctl &>/dev/null; then
        error "Missing required command: v4l2-ctl"
        ERROR=yes
    fi

    if [[ ! -d $FAKER_PATH ]]; then
        error "Missing Linux-Fake-Background-Webcam checked out at:"
        error "$FAKER_PATH"
        ERROR=yes
    fi

    if [[ $ERROR == "yes" ]]; then
        error "One or more dependencies missing, exiting"
        exit 1
    fi
}

function main() {
    check_dependencies

    local LOOPBACK_VIDEO="$(blurred_cam_video_nr)"

    if [[ -z "$LOOPBACK_VIDEO" ]]; then
        inform "No V4L2 loopback device found, creating one..."

        create_loopback_cam
        sleep 0.2
        LOOPBACK_VIDEO="$(blurred_cam_video_nr)"

        inform "Created V4L2 loopback device on $LOOPBACK_VIDEO"
    fi

    inform "Starting fake cam on $LOOPBACK_VIDEO"

    start_fake_cam "$LOOPBACK_VIDEO"
}

main

[fangfufu]

Reopening the issue because it contains an interesting script, I might incorporate it in future 🙂

[soliis-jones]

Alright, I found the culprit. As long as Discord is open in the background, it will consume the fake exactly 4 times in an instant, approximately every 3 seconds, which makes the camera stutter. Very weird... Anyone else have the same issue? Any suggestions for a workaround?

Would just like to add that this was my exact issue as well. Closing Discord solved the problem. Would love to have discord open in the background as well though.