webpdt

webp.datatype 45.1 (12.11.2026)

A picture datatype that reads WEBP files. Once it is installed, every
program that opens pictures through datatypes.library (MultiView, the
Workbench, image viewers, anything that asks the system for a picture)
opens WEBP files too, without knowing anything about the format.

This archive is for AmigaOS 4.1.
There is one archive for AmigaOS 3.x (68020 or better), one for
AmigaOS 4.1 and one for MorphOS 3. AROS has a WEBP datatype of its own
in the system and needs none of them.

It reads lossy pictures (VP8), lossless pictures (VP8L), pictures with
alpha in both forms, and the first frame of an animation. It does not
write WEBP files and it does not play animations.

The decoding is done by libwebp 1.6.0, the reference library of the
WebM project, unchanged.


INSTALLING

  Open a Shell, change to this drawer and type

      Execute Install

  or copy the two files by hand:

      Classes/DataTypes/webp.datatype   to   SYS:Classes/DataTypes/
      Devs/DataTypes/WebP               to   DEVS:DataTypes/

  and then restart, or tell the system about the new descriptor:

      AddDataTypes REFRESH

  If a webp.datatype is installed already, Install shows its version
  and asks before it replaces it. Another WEBP datatype uses the same
  two file names, so only one can be installed at a time.

  The descriptor recognises a file by its first twelve bytes, not by
  its name: a WEBP file without the .webp extension is recognised too.


REMOVING

  Delete SYS:Classes/DataTypes/webp.datatype and DEVS:DataTypes/WebP,
  then restart.


WHAT EACH SYSTEM GETS

  A datatype hands its pixels to the system's picture.datatype, and
  what that one can take differs.

  AmigaOS 4.1, MorphOS, and AmigaOS 3.2 with picture.datatype 47.9 or
  later: true colour, and the alpha channel is kept.

  AmigaOS 3.5, 3.9, 3.1.4, an older 3.2, or 3.0/3.1 with the
  picture.datatype of a graphics card system (V43 to 47.8): true
  colour. These do not know about alpha, so a picture with alpha is
  laid on a white background first.

  Plain AmigaOS 3.0/3.1 (picture.datatype V39 to V42): a planar picture
  with the best 256 colours for it, dithered. Pixels that are less than
  half opaque become the transparent colour.

  On a 68000 the library refuses to open, and WEBP files are simply not
  recognised.


CHECKING AN INSTALLATION

  Extras/dtprobe opens a picture through datatypes.library, the way any
  program does, and says what came back:

      Extras/dtprobe Extras/pictures/alpha-lossy.webp

  The last line is a checksum of the pixels. The checksums the test
  pictures in Extras/pictures must give are in docs/CHECKS.md, in the
  source.


MEMORY AND SPEED

  A picture is decoded at its full size, in one go. While it is opened
  the decoded pixels exist twice for a moment: a 512 x 512 picture with
  alpha needs 2 MB for that moment, plus the file. Pictures of more than
  8192 x 8192 pixels and files of more than 64 MB are refused.

  On a 68020 the decoding is not quick. On a stock A1200 (14 MHz) a
  512 x 512 lossy picture with alpha opens in 17 seconds, a lossless
  one in 9, a 320 x 240 lossy picture in under 5.


STATUS

  This is the first release. It was run in emulators on every system it
  is made for and, with dtprobe, on three real machines. What was tried
  and what was not is in docs/CHECKS.md, in the source.


OTHER WEBP DATATYPES

  This is not the first WEBP datatype for these systems. Aminet already
  has these:

      util/dtype/webp_dt.lha        AmigaOS 4, the first one, from 2010
      util/dtype/WarpWebPdt.lha     AmigaOS 3.x (a version for each 68k
                                    CPU), AmigaOS 4, WarpOS and MorphOS
      util/dtype/WebPDatatype.lha   AmigaOS 3.x, 68020 or better

  If one of them is installed and does what you need, you do not need
  this one. Two WEBP datatypes installed at the same time leave the
  choice between them to the system, so keep only one.

  What this one adds is support for the picture.datatype of a plain
  AmigaOS 3.0 or 3.1 (V39 to V42), which takes no true colour: there it
  hands over the best 256 colours for the picture. Its source is free
  under the GPL, and it is built on libwebp 1.6.0.


SOURCE AND LICENCE

  https://github.com/kaffeine1/webp-datatype
  This archive was built from commit 8323d5fed5d0.

  webp.datatype is free software under the GNU General Public License,
  version 3 or (at your option) any later version: see COPYING.
  Copyright (c) 2026 Michele Dipace.

  libwebp is Copyright (c) 2010 Google Inc. and is under its own BSD
  3-clause licence, with a patent grant: see COPYING.libwebp and
  PATENTS.libwebp.


HISTORY

  45.1 (12.11.2026)   First release.