VirtualContactSheet 2.0.0

VirtualContactSheet (.NET)

Virtual Contact Sheet — a contact-sheet generator, originally a C# port of vcs.rb. It composes a grid ("contact sheet") with a metadata header, optional title, per-thumbnail captions, drop shadows, polaroid frames, and a signature footer — either from frames extracted from a video at regular intervals, or from a folder (or list) of images.

• Frame capture & metadata: FFMpegCore — wraps ffmpeg / ffprobe; binaries can be on PATH or pointed to via ffBinaryFolder
• Composition / drawing: SkiaSharp (MIT) — chosen for its native drop-shadow, text, and canvas compositing support
• Image decoding: SkiaSharp again — jpg, png, gif, bmp, webp, heif/heic, avif …, with EXIF orientation applied
• Targets: .NET 10, cross-platform (Windows / Linux / macOS)

Example

A 4×4 contact sheet with a custom footer:

using VirtualContactSheet;
using VirtualContactSheet.VideoProcessing;

var video = new Video("ons3on3cup_hdtv.mp4");

var options = new ContactSheetOptions
{
    Columns = 4,
    Rows = 4,
    Signature = "Made in .NET with VirtualContactSheet",
};

await video.SaveContactSheetAsync("example-contact-sheet.png", options);

Or with the CLI:

vcs ons3on3cup_hdtv.mp4 -c 4 -r 4 -s "Made in .NET with VirtualContactSheet" -o example-contact-sheet.png

The same thing from a folder of photos, no ffmpeg involved:

using VirtualContactSheet;
using VirtualContactSheet.ImageProcessing;

var photos = ImageCollection.FromFolder("holiday");

var options = new ContactSheetOptions
{
    Columns = 4,
    Rows = 4,
    Signature = "Made in .NET with VirtualContactSheet",
    Format = SheetFormat.Jpg,
};

await photos.SaveContactSheetAsync("example-image-contact-sheet.jpg", options);

Cells are a uniform size, so the two portrait shots are letterboxed into the landscape cell the rest of the folder dictates — new SkiaImageLoader(ImageFit.Cover) crops them to fill instead.

Upgrading from VideoContactSheet

The project was renamed in 2.0.0, and so were the packages. VideoContactSheet stops at 1.0.1; nothing upgrades in place.

Both CLI packages install a command called vcs, so uninstall the old tool before installing the new one:

dotnet tool uninstall -g VideoContactSheet.Cli
dotnet tool install -g VirtualContactSheet.Cli

In library code, video types moved to their own namespace, so add one using:

using VirtualContactSheet;
using VirtualContactSheet.VideoProcessing;   // Video, VideoInfo, IFrameCapturer, ...

HeaderBuilder is now VideoHeaderBuilder, and ContactSheet.Thumbnail carries a string? Caption instead of a TimeIndex — the Thumbnail(SKBitmap, TimeIndex, bool) constructor still exists and formats the timestamp for you. See CHANGELOG.md.

Requirements

• .NET 10 SDK
• ffmpeg and ffprobe — only for video; image sheets need neither
• On headless Linux, you may also need libfontconfig1 for text rendering

Getting ffmpeg

The library never ships ffmpeg: it looks for the binaries on PATH, or wherever ffBinaryFolder points. Any of these works:

tools/download-ffmpeg.ps1 fetches the version pinned in tools/ffmpeg.json, verifies its SHA-256, and drops it in tools/ffmpeg/win-x64/, from where the CLI build copies it next to vcs.exe. That copy is a convenience for local development — the binaries are git-ignored, are never published in either NuGet package, and the build works fine without them.

Namespaces

Library usage — video

using VirtualContactSheet;
using VirtualContactSheet.VideoProcessing;

// ffmpeg/ffprobe on PATH:
var video = new Video("movie.mkv");

// — or — binaries shipped next to the exe:
var video = new Video("movie.mkv", ffBinaryFolder: AppContext.BaseDirectory);

// Metadata
var info = await video.GetInfoAsync();
Console.WriteLine($"Duration: {info.Duration}, {info.Video?.Width}x{info.Video?.Height}");

// Build a 3x3 sheet
var options = new ContactSheetOptions
{
    Columns = 3,
    Rows = 3,
    ThumbnailWidth = 320,
    Format = SheetFormat.Jpg,
    Title = "My Movie",
    SoftShadow = true,
    Timestamp = true,
};
await video.SaveContactSheetAsync("out.jpg", options);

// Single frame
var bmp = await video.CaptureFrameAsync(TimeIndex.Parse("1:22"), width: 640, evadeBlank: true);

Library usage — images

ImageCollection mirrors Video: point it at a source, reuse the same ContactSheetOptions, and call the same SaveContactSheetAsync. No ffmpeg involved.

using VirtualContactSheet;
using VirtualContactSheet.ImageProcessing;

// Every supported image in a folder, ordered by file name:
var photos = ImageCollection.FromFolder("holiday-2026", recursive: true);

// — or — an explicit list, kept in the order given:
var photos = ImageCollection.FromFiles(["cover.jpg", "beach.png", "sunset.jpg"]);

// Metadata (dimensions/format/size per image, read from the file headers)
var info = await photos.GetInfoAsync();
Console.WriteLine($"{info.Count} images, {info.First?.Width}x{info.First?.Height}");

var options = new ContactSheetOptions
{
    Columns = 4,
    Rows = 4,
    ThumbnailWidth = 320,
    Title = "Holiday 2026",
    Format = SheetFormat.Jpg,
};

await photos.SaveContactSheetAsync("holiday.jpg", options);

How the options map to images

Extra knobs that live on the collection itself:

// More images than cells? Sample evenly (default) or render all of them.
photos.Selection = ImageSelection.All;

// Caption text per thumbnail; return null for none.
photos.Caption = image => Path.GetFileNameWithoutExtension(image.Path);

// Cells are uniform, so images that do not match are letterboxed (default),
// cropped, or stretched:
var cropped = ImageCollection.FromFolder("photos", loader: new SkiaImageLoader(ImageFit.Cover));

Implement IImageLoader (or IImageInfoProvider) to plug in a different decoder, exactly like IFrameCapturer for video.

CLI

Install as a .NET global tool (requires ffmpeg/ffprobe on PATH):

dotnet tool install -g VirtualContactSheet.Cli

The vcs CLI mirrors the original script's options:

vcs video.avi
vcs -i 3m30 input.wmv -o output.jpg
vcs --from 3m --to 18m -i 2m input.avi
vcs -c 4 -r 5 --polaroid --no-shadow -T "Holiday" clip.mp4

It takes images too — pass a folder, or the image files themselves:

vcs holiday/                          # one sheet from the folder -> holiday.png
vcs holiday/ --recursive --all        # every image, subfolders included
vcs holiday/ --fit cover -c 5 -r 4    # crop to fill the cells instead of letterboxing
vcs holiday/*.jpg -o summer.jpg -f jpg

Each video and each folder produces its own sheet; loose image files are combined into a single one. Wildcards are expanded by vcs itself, so vcs holiday/*.jpg behaves the same in cmd and PowerShell as it does in a POSIX shell.

Using an option against the wrong kind of input is an error rather than a silent no-op, unless the run mixes both — vcs clip.mp4 holiday/ -i 2m is fine, and the interval applies to the video.

Run vcs --help for the full list. Use --ffmpeg-folder <dir> to point at a local copy of the binaries instead of relying on PATH; image sheets never invoke ffmpeg at all.

Feature mapping vs. vcs.rb

Architecture

ContactSheet                  SkiaSharp grid composition + styling   (shared)
 └─ ContactSheetOptions       all grid/style/filter settings

VideoProcessing
 Video                        orchestrator (probe → capture → compose)
 ├─ IVideoInfoProvider        metadata abstraction
 │   └─ FfprobeVideoInfoProvider   FFProbe.AnalyseAsync → VideoInfo
 ├─ IFrameCapturer            frame extraction abstraction
 │   └─ FfmpegCapturer        FFMpegCore pipe → PNG → SKBitmap
 └─ TimeIndex                 flexible time parsing ("3m30", "1:22", "90")

ImageProcessing
 ImageCollection              orchestrator (probe → load/scale → compose)
 ├─ IImageInfoProvider        metadata abstraction
 │   └─ SkiaImageInfoProvider SKCodec header → ImageInfo
 ├─ IImageLoader              decode/scale abstraction
 │   └─ SkiaImageLoader       decode → EXIF straighten → fit the cell (contain/cover/stretch)
 └─ ImageSelection            how a large collection is reduced to the grid

Swap in another capturer (libav, mplayer) by implementing IFrameCapturer and passing it to the Video constructor; the same goes for IImageLoader and ImageCollection.

Changelog

See CHANGELOG.md.

License

Mirror of a GPL-3.0 project; treat this port accordingly.