SharpApng.Cli 0.3.0

sharpapng

Command line tool for building and inspecting animated PNGs.

dotnet tool install --global SharpApng.Cli

sharpapng create -o walk.png -d 80 frame*.png   # build an animation
sharpapng convert logo.gif                      # GIF, JPEG or BMP to PNG
sharpapng resize photo.jpg -s 256               # thumbnail, aspect preserved
sharpapng info walk.png                         # frame list, delays, offsets
sharpapng extract walk.png ./frames             # split back into still PNGs

create

sharpapng create --output <file> [options] <image>...

  -o, --output <file>   Where to write the APNG. Required.
  -p, --poster <file>   A still shown only by viewers without APNG support,
                        kept out of the animation. Must match the canvas.
  -d, --delay <ms>      Milliseconds per frame. Default 100.
  -l, --loop <n>        Play count; 0 loops forever. Default 0.
      --16-bit          Store 16 bits per channel instead of 8.
      --no-optimize     Store every frame whole instead of just what changed.
      --fast            Compress quickly rather than tightly.
      --smallest        Compress as tightly as zlib allows.
      --zopfli          Compress with Zopfli instead of zlib.
      --zopfli-iterations <n>
                        Zopfli passes per image; implies --zopfli. Default 15.

Inputs may be PNG, JPEG, GIF (its first frame) or BMP, and every frame must match the first one's dimensions. By default only the rectangle that changed between frames is stored, which on typical content is a large saving: a 320×320, 24-frame animation with a small moving sprite came out 91.9 % smaller than storing whole frames.

Smaller files with Zopfli

--zopfli works with every command that writes — create, convert, resize and extract — and compresses with Zopfli instead of zlib. The files are typically 6–9 % smaller than with --smallest, with exactly the same pixels, and any PNG decoder reads them. The price is time: from a second or two for one image to minutes for a long animation. A 47-frame, 300×250 animation took 94 s instead of 1.4 s, a 12-frame one 13 s instead of 0.7 s. Worth it for assets compressed once and served often.

extract writes composited frames — what a viewer displays — not the cropped sub-images the file stores internally. When the file carries a separate poster, it comes out as poster.png, and create --poster puts it back.

Checking a deployed file

CDN optimisers, CMS thumbnail steps and build tasks such as imagemin or pngquant re-encode PNGs and silently discard the chunks that carry the animation. The result is a valid PNG that no longer moves, with no error anywhere to announce it. info reports it directly:

$ sharpapng info deployed.png
Container  : PNG
Animated   : no
Frames     : 1

This PNG carries no acTL chunk, so it is a still image. ...

Standalone binaries

If you would rather not install a .NET runtime, each release also ships a single self-contained executable for Windows x64/x86/ARM64, Linux x64/ARM64/ARM and macOS on both architectures.

Built on SharpApng, a dependency-free APNG library. --zopfli uses ZopfliSharp, which the tool includes under the Apache License 2.0; its licence and NOTICE are in THIRD-PARTY-NOTICES.md, shipped in this package and in every release archive.

Source and documentation · MIT, ZopfliSharp Apache-2.0