webp-lossless-bitstream-spec: use RFC 7405 for ABNF

This allows for case sensitive literals.

Bug: webp:611
Change-Id: I5258c67ab12c48593d433449328fd85d461a05d2
This commit is contained in:
James Zern 2023-07-14 11:40:04 -07:00
parent 6c6b3fd317
commit 56cf562570

View File

@ -1062,9 +1062,9 @@ The interpretation of S depends on its value:
7 Overall Structure of the Format
---------------------------------
Below is a view into the format in Augmented Backus-Naur Form ([ABNF]). It does
not cover all details. The end-of-image (EOI) is only implicitly coded into the
number of pixels (xsize * ysize).
Below is a view into the format in Augmented Backus-Naur Form (ABNF)
[RFC 5234][] [RFC 7405][]. It does not cover all details. The end-of-image (EOI)
is only implicitly coded into the number of pixels (xsize * ysize).
Note that `*element` means `element` can be repeated 0 or more times. `5element`
means `element` is repeated exactly 5 times. `%b` represents a binary value.
@ -1073,7 +1073,7 @@ means `element` is repeated exactly 5 times. `%b` represents a binary value.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
format = RIFF-header image-header image-stream
RIFF-header = "RIFF" 4OCTET "WEBP" "VP8L" 4OCTET
RIFF-header = %s"RIFF" 4OCTET %s"WEBPVP8L" 4OCTET
image-header = %x2F image-size alpha-is-used version
image-size = 14BIT 14BIT ; width - 1, height - 1
alpha-is-used = 1BIT
@ -1140,5 +1140,6 @@ RIFF-header image-size %b1 subtract-green-tx
%b0 prefix-codes lz77-coded-image
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[ABNF]: https://www.rfc-editor.org/rfc/rfc5234
[RFC 5234]: https://www.rfc-editor.org/rfc/rfc5234
[RFC 7405]: https://www.rfc-editor.org/rfc/rfc7405
[canonical_huff]: https://en.wikipedia.org/wiki/Canonical_Huffman_code