Talks and demos

I keep demo commands in a plain PowerShell file, so I can rehearse, record and present the same sequence. ConsoleMonster types them into a real PowerShell shell, waits for it to finish, and records the actual terminal output.

Write a demo

Typed demos use PowerShell 7. Save this as demo.ps1:

# demo: setup
function prompt { 'demo> ' }
# demo: wpm 140
# demo: chapter Calculate
Write-Host ('The answer is ' + (6 * 7)) -ForegroundColor Cyan
# demo: pause 1
# demo: chapter Report
'Compile: passed', 'Tests: 24 passed', 'Package: ready'
# demo: wait Package: ready
# demo: pause 2

Directives are comment lines beginning with # demo:. Ordinary PowerShell remains ordinary PowerShell; multiline commands, functions, pipelines and here-strings stay together.

-Seed fixes the typing jitter. Keep fixtures, culture, timestamps and command results fixed too: a live network, random data or the current time still produces different output. Real command execution and operating-system scheduling determine output timing. Setup hides its own output; it is not a security boundary for commands that later print the same data. Redaction protects the saved recording; live terminal output remains unredacted.

The driver wraps the shell's actual prompt in OSC 133 semantic marks. It never searches for PS C:\> or a directory name, so a custom prompt, another language or a different OS does not change readiness detection. Each command executes in the same child PowerShell scope. Commands should finish unattended; interactive password prompts and full-screen applications need an ordinary session recording.

Record and export

Import-Module ConsoleMonster
Invoke-ConsoleDemo -Path ./demo.ps1 -Destination ./talk.cast -Seed 42
Export-ConsoleRecording -Path ./talk.cast -Format Gif -Preset Slide16x9 -WindowChrome -Destination ./talk.gif
Export-ConsoleRecording -Path ./talk.cast -Format Mp4 -Preset Slide16x9 -WindowChrome -Destination ./talk.mp4

PNG, GIF and APNG run without an external executable. MP4 pipes RGBA frames to ffmpeg on PATH and writes H.264 with yuv420p pixels and fast-start metadata; it has no audio track. If ffmpeg is missing, use GIF or install ffmpeg separately. It is never a package dependency.

-FramesPerSecond is the maximum sample rate (10 by default). Identical frames are merged; GIF uses a shared quantised palette. -IdleLimit 2 caps unchanged-frame delays while the final frame has its own hold. Use zero to keep original timing. -LoopCount 0 loops indefinitely; one plays once. MP4 is a single pass; choose repetition in your slide tool. APNG preserves full-colour pixels for software that supports it.

Every slide preset centres the complete window inside a safe inset of 6% of the canvas's short side. Opposite margins match; the extra space follows the window's aspect ratio. Rounded corners, a subtle shadow and a fine border keep the bottom edge visible. PNG, GIF, APNG and MP4 share this composition.

-Fit Content is the slide default: stills trim trailing empty rows and columns, keeping two columns of padding after the content. Animations reserve the widest and tallest content used anywhere in the clip. The window stays in one place as commands type. -Fit Terminal keeps the complete grid, including empty rows and columns. In both modes, the font grows until width or height reaches the inset, up to 72 pixels. Docs keeps its natural-size layout.

The surrounding background uses the theme colour by default. Choose a solid colour or a soft gradient with hex colours:

Export-ConsoleRecording ./talk.cast -Format Png -Preset Slide16x9 -Fit Terminal -Background Solid -BackgroundColor '#1b2638' -Destination ./terminal.png
Export-ConsoleRecording ./talk.cast -Format Mp4 -Preset Slide16x9 -Background Gradient -BackgroundColor '#192332' -BackgroundEndColor '#0c0c0c' -Destination ./talk.mp4

Use -Theme Dark, Light or HighContrast, and -ChromeStyle MacOS, Windows, Linux or None. The embedded JetBrains Mono font makes default text consistent across operating systems. -FontFamily 'Consolas' chooses an installed font; C# also accepts additional fallback families. Emoji and CJK coverage depends on installed fonts. Box drawing, blocks and braille use geometric cell shapes, so they join without font seams.

Export still slides

# Final frame, or a moment in source-recording time.
Export-ConsoleRecording ./talk.cast -Format Png -Preset Slide16x9 -Destination ./final.png
Export-ConsoleRecording ./talk.cast -Format Png -At '00:00:04' -Preset Slide16x9 -Destination ./moment.png

# A chapter's completed view, or numbered slides for every chapter.
Export-ConsoleRecording ./talk.cast -Format Png -Chapter Report -Preset Slide16x9 -Destination ./report.png
Export-ConsoleRecording ./talk.cast -Format Png -PerChapter -Preset Slide16x9 -Destination ./slides

# Export any widget or rendered frame too.
New-ConsoleText 'Ready for the talk' | Export-ConsoleFrame -Format Png -Preset Social -Path ./ready.png

-Chapter selects the last view before the next chapter; the last chapter uses the final frame. -PerChapter writes slide-001.png, slide-002.png and so on into a directory. Source-time selection happens before playback speed or idle compression. Choose one of -At, -Chapter, -PerChapter or -FinalFrame.

Present live

Start-ConsoleDemo -Path ./demo.ps1
Start-ConsoleDemo -Path ./demo.ps1 -Record ./on-stage.cast

The terminal title shows the current step. Commands run in a dedicated real PowerShell shell; closing the demo stops that child and restores the title. Without -Record, temporary recording files are removed on exit.

Use a terminal such as Terminal.app, iTerm2 or Windows Terminal. Keep the window at the intended recording size during a take. Rehearse the script with the same shell, data and module versions you will use on stage.

Put it in slides

PNG works for stills in all three. Animated SVG commonly appears as a still in slide tools; use GIF or video when the typing needs to move. APNG support varies, so GIF is the portable animated-image choice. PowerPoint for the web has different GIF playback limitations from the desktop app.

See Microsoft's GIF guide, PowerPoint video formats, Keynote media and Google Slides image and video insertion.

C#

Add the ConsoleMonster and ConsoleMonster.Graphics packages. The core package has no runtime package dependencies; the graphics add-on brings ChartForgeX and ChartForgeX.Stories. The PowerShell module includes the add-on and loads graphics assemblies on first use.

using ConsoleMonster.Demos;
using ConsoleMonster.Graphics;
using ConsoleMonster.Sessions;

var demo = DemoScript.Read("demo.ps1");
var options = new DemoOptions {
    Seed = 42,
    Recording = new SessionRecordingOptions {
        Path = "talk.cast", Shell = "pwsh", Width = 100, Height = 28
    },
    Output = Console.Write
};
ConsoleDemo.Record(demo, options);
var recording = SessionRecording.Read("talk.cast");
var slides = new GraphicsExportOptions { Preset = GraphicsPreset.Slide16x9 };
recording.SaveGraphics("talk.gif", GraphicsFormat.Gif, slides);
recording.SaveChapterPngs("slides", slides);

For live presentation use ConsoleDemo.Present(demo, options). Pass stepChanged to display a custom step counter and a cancellation token to stop the owned child.

The repository includes a complete PowerShell recording example and a runnable C# example. Both use synthetic data. The recording example works from a neutral demo: filesystem drive, so genuine errors show demo:/missing.json instead of a machine's real working path. It pipes the error record through Write-ConsoleText -Color Red to show the message without PowerShell's source-location header. Its example token is labelled synthetic and needs no redaction.