credit RFC 9649 for the WebP container and lossless codec

The short distance code table is taken from the RFC, whose code components
come under the Revised BSD License: the notice is in the vp8l.ts header and
THIRD_PARTY_NOTICES.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ljnxm1Qjrocq1izGajLx8J

Author: matmen

README.md

@@ -87,7 +87,7 @@ The deflate/inflate implementation is derived from [fflate](https://github.com/1
 [Fast CRC32 in JavaScript](https://gist.github.com/101arrowz/e58695f7ccfdf74f60ba22018093edea), both by Arjun Barrett.
 The JPEG codec is based in part on the work of the Independent JPEG Group (libjpeg) and on
 [pdf.js](https://github.com/mozilla/pdf.js), the glyph rasterizer is translated from
-[font-rs](https://github.com/raphlinus/font-rs). The WebP decoder follows [RFC 6386](https://www.rfc-editor.org/rfc/rfc6386)
+[font-rs](https://github.com/raphlinus/font-rs). The WebP codecs follow [RFC 9649](https://www.rfc-editor.org/rfc/rfc9649) and [RFC 6386](https://www.rfc-editor.org/rfc/rfc6386)
 and reproduces [libwebp](https://chromium.googlesource.com/webm/libwebp)'s color conversion. See [THIRD_PARTY_NOTICES.md](THIRD_PARTY_NOTICES.md) for their licenses.
 
 ---

THIRD_PARTY_NOTICES.md

@@ -10,6 +10,7 @@ following projects, under their own licenses. Each derived file says so in its h
 | [libjpeg](https://ijg.org/) / [libjpeg-turbo](https://libjpeg-turbo.org/) by the Independent JPEG Group | `src/codecs/jpeg.ts` (IDCT, FDCT, upsampling, color conversion, progressive refinement, optimal Huffman tables) | IJG |
 | [pdf.js](https://github.com/mozilla/pdf.js) (forked from [jpgjs](https://github.com/notmasteryet/jpgjs) by notmasteryet) | `src/codecs/jpeg.ts` (structure of the scan decoder) | Apache-2.0 |
 | [font-rs](https://github.com/raphlinus/font-rs) by Raph Levien | `src/render/text.ts` (the `Rasterizer` class, also used for SVGs) | Apache-2.0 |
+| [RFC 9649](https://www.rfc-editor.org/rfc/rfc9649) (WebP Image Format) | `src/codecs/vp8l.ts` (lossless bitstream, short distance code table), `src/codecs/webp.ts` (container) | BSD-3-Clause (Revised BSD) |
 | [RFC 6386](https://www.rfc-editor.org/rfc/rfc6386) (VP8 Data Format and Decoding Guide, with the libvpx reference decoder) | `src/codecs/vp8-tables.ts` (probability and quantizer tables), `src/codecs/vp8.ts` (decoding procedures) | BSD-3-Clause |
 | [libwebp](https://chromium.googlesource.com/webm/libwebp) | `src/codecs/vp8.ts` (YUV to RGB conversion, "fancy" chroma upsampling), `src/codecs/webp.ts` (animation frame blending) | BSD-3-Clause |
 
@@ -115,3 +116,29 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ```
 
 The RFC's reference decoder additionally comes with Google's patent grant for VP8 (RFC 6386 section 20.27).
+
+## RFC 9649
+
+The WebP container and the lossless (VP8L) codec follow RFC 9649, the short distance code table is taken from it.
+
+```
+Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+  disclaimer.
+- Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other materials provided with the distribution.
+- Neither the name of Internet Society, IETF or IETF Trust, nor the names of specific contributors, may be used to
+  endorse or promote products derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+```

src/codecs/vp8l.ts

@@ -1,4 +1,8 @@
-// WebP lossless (VP8L) bitstream, as specified in RFC 9649 section 3 onwards
+/*!
+ * WebP lossless (VP8L) bitstream, as specified in RFC 9649 ("WebP Image Format") section 3 onwards, including its
+ * table of short distance codes. Copyright (c) 2024 IETF Trust and the persons identified as the document authors,
+ * Revised BSD License (see THIRD_PARTY_NOTICES.md)
+ */
 
 /** decoded VP8L image: ARGB pixels (0xAARRGGBB) */
 export interface VP8LImage {

src/codecs/webp.ts

@@ -2,7 +2,8 @@
  * WebP container. Animation frames are blended with libwebp's integer arithmetic (Copyright (c) 2010 Google Inc., BSD
  * license, see THIRD_PARTY_NOTICES.md)
  */
-// RIFF container (RFC 9649): simple lossy/lossless files, extended files with alpha and animation
+// RIFF container (RFC 9649, https://www.rfc-editor.org/rfc/rfc9649): simple lossy/lossless files, extended files with
+// alpha and animation
 import * as vp8l from './vp8l.ts';
 import * as vp8 from './vp8.ts';
 import { orientation as exifOrientation } from './exif.ts';