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electroncapture

Playback video in a frameless electron app for screen-sharing and window capture

This is the Electron Capture app,

Created originally for VDO.Ninja users, it can provide users a clean way of window capturing websites or as a production-oriented Chrome-alternative with numerous performance tweaks. It can also be used to pin live chat overlays on screen, screen share without user interaction, increase the resolution of Zoom streams, and much much more.

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Why was this made ?

On some systems the OBS Browser Source plugin isn’t available or doesn’t work all that well, so this tool was made as a viable agnostic alternative. It was originally built to let you cleanly screen-grab just a video stream without the need of the OBS Browser Source plugin. The app was also made to make selecting the output audio playback device easy, outputting audio to something such as a Virtual Audio device: ie) https://vb-audio.com/Cable/ (Windows & macOS; donationware) or VAC (Windows @ https://vac.muzychenko.net/), or Loopback (macOS).

While the OBS Browser source is ever maturing, and issues with video smearing, crashing, and dropped audio are far less common these days, there are still user reports of desync issues and other mishaps with OBS browser sources. As a result, Electron Capture remains the preference for many professional VDO.Ninja users, and over time it has evolved to offer additional solutions for many different use cases in the video production world.

The app can be set to remain on top of other windows, can hide the mouse cursor when possible, provides accurate window sizes options for 1:1 pixel mapping, and supports global system hotkeys (CTRL+M on Windows, for example). It also offers relatively low-CPU usage, command-line launch tools, built-in recording options, and it won’t crash if OBS crashes. It may be worth exploring before your next production.

The Electron Capture app uses recent versions of Chromium, and is setup to more resistant to desync, video smearing, and other issues that might exist in the native OBS browser source capture method. If a cutting edge web feature becomes available within browsers, it will also become available to Electron Capture first, making certain experimental features within VDO.Ninja accessible. The app is also optimized to not throttle when the system is stressed, ensuring that production-critical web-oriented code and media does not slow down or stop when its most needed.

For non-VDO.Ninja users, the window-sharing focus of Electron Capture is also useful for Zoom or other users. For example, when screen sharing it into Zoom, the published video will be high-resolution, since Zoom publishes virtual webcam and other camera streams at lower quality compared to screen shares. You can screen share websites without the browser frame, search history, or nav bar from appearing. When doing a Power Point presentation, you can screen share the window via Electron Capture, while also pinning the it in place on top, avoiding having to toggle between multiple windows as you present.

More benefits listed here

Lastly, since playback is agnostic, you can window-capture the same video multiple times, using one copy in a mixed-down live stream, while using a window-capture to record a clean full-resolution isolated video stream. Both YouTube, Twitch, Facebook, and more are supported in this regard, where a full-window clean output option is available for those sites as well. There’s even optimizations for sites like Twitch, letting you easily full-window any video on the page, without overlays or other effects from appearing.

Video guide on how to use Electron Capture

Video Guide for Electron

Settings and Parameters

Parameter Alias Description Example values Notes
–width -w The width of the window in pixels. 1280 Value in px
–height -h The height of the window in pixels. 720 Value in px
–x -x The x-position of the window in pixels. 100 Value in px
–y -y The y-position of the window in pixels. 100 Value in px
–url -u The URL of the window to load. “https://vdo.ninja/electron”  
–title -t The default Title for the app Window. “My App” Handy for use with OBS window capture
–pin -p Enables always on top.    
–hwa -a Enables Hardware Acceleration.    
–node -n Enables node-integration.    
–minimized –min Starts the window minimized.    
–fullscreen -f Enables full-screen mode for the first window on its load.    
–unclickable –uc The page will pass through any mouse clicks or other mouse events.    
–savefolder –sf Where to save a file on disk. “/path/to/folder”  
–mediafoundation, –mf Enables media foundation video capture.    
–disablemediafoundation –dmf Disables media foundation video capture; helps capture some webcams.    
–chroma –color Set background CSS to target hex color. “FFF” or “0000”  

The optional Command Line arguments can be seen as examples below, along with their default values.

elecap.exe --width=1280 --height=720 --url="https://vdo.ninja/electron" --title="my Window name" --x=1 --y=1 --node=1

As shown above, using an equal sign (=) and double quotes to encapsulate strings is recommended for Windows command line / batch file users.

On Linux or mac though, you might be able to get away with the following though:

./elecap -w 1280 -h 720 -u 'https://vdo.ninja/electron' -t 'my Window name' --x 10 --y 10 -n 1

As well, if running from Windows command prompt, without encapsulating quotes, any ampersand “&” characters will need to be escaped with a “^” character, as seen below:

elecap -t=feed2 --url https://vdo.ninja/?view=ePz9hnx^&scene^&codec=h264^&room=SOMETHINGTEST123

The above usage isn’t probably ideally suited for windows users though, but it might work.

You can also use it like this, if you are in the same folder as the app itself, and so long as the complex string value is last.

elecap.exe --node true --title feed2 --url "https://vdo.ninja/?view=ePz9hnx&scene&codec=h264&room=SOMETHINGTEST123"

Note that the elecap.exe is the ‘portable’ version of Electron Capture; you can choose the installer or the single-file portable version. I personally find the portable one easier to use via command line, with the installer version better without command line usage.

If running from a Windows batch file with the goal of launching multiple instances at a time, try the following as an example:

start elecap.exe -w 640 -h 360 -x 0 -y 0 -s -u="https://vdo.ninja/?scene&fakeguests=1&room=SOMETHINGTEST123" -t="Guest 1" -p
timeout /T 1
start elecap.exe -w 640 -h 360 -x 640 -y 0 -u="https://vdo.ninja/?scene&fakeguests=1&room=SOMETHINGTEST123" -t="Guest 2" -p
timeout /T 1
start elecap.exe -w 640 -h 360 -x 0 -y 360 -u="https://vdo.ninja/?scene&fakeguests=1&room=SOMETHINGTEST123" -t="Guest 3" -p
timeout /T 1
start elecap.exe -w 640 -h 360 -x 640 -y 360 -u="https://vdo.ninja/?scene&fakeguests=1&room=SOMETHINGTEST123" -t="Guest 4" -p

If you right-click the application, you’ll get a context menu with additional options. Changing resolutions dynamically is an option, for example.

Screen-share, global hotkeys, and user-prompts

screen sharing

Starting with version 1.6.0, to enable screen-share support and some other features, the app needs Node Integration enabled; aka, Elevated Privileges. This will allow remote websites to run node-based code, which is a security concern if visiting untrusted websites.

You can enable Elevated Privileges for the app via the command line with --node 1 or in the app by right-clicking and selecting “Elevate Privileges” from the context-menu. If right-clicking to enable this mode, the app may reload the page afterwards.

A unique feature about the Electron Capture app is that it can auto-select a screen or window when screen-sharing with VDO.Ninja, without user-input. Adding to the VDO.Ninja URL, &ss=1 will select display 1, &ss=2 for the second display, etc. Or specify a window with &ss=window_name_here.

To select Screen 1 automatically on load, for example you can do:

elecap.exe --node 1 --url="https://vdo.ninja/beta/?ss=1&autostart"

or to select Discord automatically

elecap.exe --node 1 --url="https://vdo.ninja/beta/?ss=Discord&autostart"

It’s also possible to select audio-only when screen sharing via Electron Capture with VDO.Ninja; you do not need to select a video if you wish to share audio-only.

global hotkeys

Global Hotkeys, such as CTRL+M, are supported. CTRL+M will mute the mic, in the most recently opened window. You can assign a custom global hot-key in VDO.Ninja, and it will be respected by Electron Capture. (VDO.Ninja Settings -> User -> Global Hotkey)

Youtube has a built-in automatic ad-skipper added, and for both Youtube, Twitch, and more, when watching a video, you can full-window the video, allowing for clean video capture. This option is available via the context menu of Electron Capture; just right-click somewhere on the page that is empty and select Clean Video Output.

image

Audio Output

A popular way of outputting audio from the Electron Capture app into OBS is done using a virtual audio cable. Some such cables include:

Mac Audio Options: https://rogueamoeba.com/loopback/ (macOS & non-free, but excellent), and https://existential.audio/blackhole/ (macOS & free) (and more here https://github.com/steveseguin/vdoninja/wiki/FAQ#macaudio)

Windows Audio Option: https://www.vb-audio.com/Cable/ (donationware)

If you intend to have more than a 6 virtual audio cables, you can try VAC instead of VB Cables, as VAC seems to support dozens of virtual audio cables, while VB Cable supports just a few: https://vac.muzychenko.net/

You can also use some advanced URL parameters to output the audio to specific channels. The following link links the parameters and the outcome, based on device/software used: https://docs.google.com/spreadsheets/d/1R-y7xZ2BCn-GzTlwqq63H8lorXecO02DU9Hu4twuhuA/edit?usp=sharing

You can still capture audio via OBS Browser source, appending &novideo to the URL to disable video. Appending &noaudio to the Electron Capture URL would conversely disable audio there, allowing you to capture audio with OBS browser source and video with Electron Capture. The audio/video sync might be slightly off in this setup, but not noticible in most cases.

More recently, with newer versions of OBS, you can capture an application’s audio using OBS natively, but with older versions you can use the following OBS plugin to also do it: https://github.com/bozbez/win-capture-audio

image

Changing the audio output device

If you right click the app when on a site, you can change the audio output device for that site. This is useful for setting a Youtube or VDO.Ninja video to output to a virtual audio cable or headphones, rather than playout via the default audio device.

On macOS, this is especially helpful since there is a lack of audio routing controls.

Please note: To use this feature, you will need to elevate the app’s privilleges, which can expose the user to security issues on untrusted websites.

Pinning and click-pass thru

You can pin the app on top of other apps via the right-click menu, and when enabled, you can then also enable “click thru” mode also via the context-menu, so no mouse input is captured. The app acts a bit like it is invisible, turning it into a bit of HUD for other applications and games.

If using socialstream or vdo.ninja, you can append &transparent to those URLs to make the background transparent. You can also use custom CSS to make web pages shown semi-transparent, so you can still see underneath.

Once “click thru” mode is enabled, you can re-enable click-capture by just selecting the app via the task bar, as bringing the app into focus will disable the click-thru mode.

Deep linking

You can load Electron Capture via deep-links in websites and web-apps; assuming you have already installed and have used the app before.

eg: electroncapture://vdo.ninja/?view=abc123 will open Elecap and load a VDO.Ninja view link.

The page below will let you customize deep links with additional settings, such as width, height, and position:

https://vdo.ninja/electroncapture

image

Syphon Output

While there is no native Syphon or NDI output option yet available, one user has mentioned a solution for some users: http://www.sigmasix.ch/syphoner/

Automation Workflows with VDO.Ninja

You can see a quick start / cheat sheet guide for example uses of the app with VDO.Ninja here: https://github.com/steveseguin/vdo.ninja/blob/quickstart/automation/cheatsheet_obsn_automation.md

Notes on Using and Closing the App

For Windows users:

For Mac users:

— WINDOW CAPTURE will have a video delay of up to ~800ms, but Windows can be stacked without issue

— DISPLAY CAPTURE will have no delay, but the windows cannot be stacked, which could be a problem if you only have one screen

Links to downloads below.

You can find the newest release builds of the app here: https://github.com/steveseguin/electroncapture/releases or see below.

Please note that the Electron Capture app does not auto-update to newer versions of Chromium. This can become a security issue if it is left to become out of date. It’s also recommended to not use the Electron Capture app with websites and remote VDO.Ninja peers that you do not trust.

Windows Version 🪟

There are two versions for Windows. An installer for x64 systems. There’s also a portable version, which is larger in size, but supports x64 and x86 (32-bit) systems. The portable version requires no install and is easier to use from the command-line or from a batch file.

New release here: https://github.com/steveseguin/electroncapture/releases/

If you have problems, try a different version or contact me on Discord.

Mac Version 🍎

If on version of Electron doesn’t work for you all that well, try a different version. There may be some issues with rounded edges depending on you macOS version and the Electron version used.

Linux Version 🐧

For most Linux users though, we’re recommending Linux users build it themselves. Details below

Getting the correct nodejs/npm versions can be hard on linux, but using snap can help there.

sudo apt-get update
sudo apt-get install snapd -y
sudo snap install node --classic --channel=18
# sudo snap refresh node --channel=20 ## If you need to update to a different version of node, to match the manifest's minimum ersion, you can do so like this I think

Next, close the shell and open a new one, to ensure the installation is completed.

To get the actual app source code and to build a distributable version, see below

git clone https://github.com/steveseguin/electroncapture
cd electroncapture
npm install
npm run build:linux

The file you need to run will be in the dist folder.

Installing / building for the Raspberry Pi 🥧

If you want to compile on Raspberry Pi, it’s possible, but keep in mind the GPU may not work without also patching Electron.js to support the GPU. Currently you’ll need to run it without hardware-acceleration disabled, which is rather disappointing. Contributions that can help fix this are welcomed.

Anyways, this is all much like with the Linux install, but we also need to install fpm before trying to build the app.

sudo apt-get update
sudo apt-get install snapd -y
sudo apt-get remove nodejs -y
sudo snap install node --classic --channel=14

 ## close the current terminal shell and open a new one here ##

sudo apt install ruby ruby-dev -y
sudo gem install fpm

We also need to build the app using build:rpi instead of build:linux, as we need to target ARM versus x64.

git clone https://github.com/steveseguin/electroncapture
cd electroncapture
npm install
npm run build:rpi

You should get a .deb file in the dist file with this option. If you install the deb file, it should appear in the Raspbian start menu, under Other -> ElectronCapture

This will probably file if you do not disable the GPU / hardware-acceration within the Electron Capture app first, but who knows – maybe you can get it working?

Building from source on Windows

You’ll also need nodejs and npm installed.

If on Windows, you can find the NPM/Nodejs install files here: https://nodejs.org/en/download/current/

and then to get the source code for Electron Capture,

git clone https://github.com/steveseguin/electroncapture.git
cd electroncapture

To just run the app from source without building, you can:

npm install
npm start

If you get an error about node versions, you can install the required version with something like this:

npm install -g [email protected]
npm install
npm run build:win32

Building the app from source on macOS :

The basic idea is is to first install node, npm, and git. Then to clone and build the folder:

git clone https://github.com/steveseguin/electroncapture.git
cd electroncapture
npm install -g [email protected]
npm install
npm run build:darwin

If you need to sign the build, for distribution, you can then try:

npm install
export appleId={[email protected]}
export appleIdPassword={app-specific-password-here}
sudo -E npm run build:darwin

Trouble-shooting – if can’t hide cursor when window capturing using OBS:

Change the capture method in OBS to “BitBlt”and uncheck the Capture Cursor. Also make sure OBS runs in compatibility mode for win 7, so you don’t get a black screen

image

image

Adding &nocursor to VDO.Ninja will hide the cursor in that browser window, but that often isn’t enough. If the above fails, make sure you are window capturing with OBS using the same display adapter for both OBS and the Electron window.

Lastly, if that still doesn’t help, you can try Windows + Tab (on windows), and host the Electron Capture app on the secondary windows desktop. Window+Tab back to the main one and select the window then. You may need to toggle between the two desktops after selecting the window to capture, to get it to show in OBS, but it is one way of hiding the mouse.

You can also drag the Electron Capture far off screen, so the cursor can’t approach it really.

Issues with dependencies when compiling

Sometimes a dependency won’t update to the value stated in the package.json.

This option might be able to update the package.json to the newest version of dependencies automatically,

npx npm-check-updates -u
npm install

Seems to work with newer npm versions

Security considerations

The Electron Capture doesn’t auto-update. This is partially because a stable browser with expected and tested outcomes is important for live streaming. Browsers that auto-update are not reliable, and introduce unexpected issues, month to month.

However, security vulnerabilities constantly appear in the browser world, making older unpatched versions a security hazard.

While I try to release builds of the Electron Capture app that are within a version or two of the newest Chromium stable release, you still will need to manually update to them. And if I do not provide them, you can build them yourself, via updating the package.json file with the target version of the electron.js framework that you wish to use.

Using Electron Capture should still be relatively safe if using it only on trusted domains, not opening unknown links with it, and not using it as a general browser for surfing the greater web with.

Please understand the security implications of using the Electron Capture app, as although it’s very powerful, using it improperly can get you hurt.

Thank you

“Electron capture is one process that unstable atoms can use to become more stable. “ - https://education.jlab.org/glossary/electroncapture.html