Commit Graph

89 Commits

Author SHA1 Message Date
James Zern
9db21143d0 webp-container-spec: change assert to MUST be TRUE
in the 'Canvas Assembly from Frames' section. This matches the format in
the RFC draft; assert was not defined

Change-Id: Ib943b42f75fd1b4c281848f14e0626df9c868f59
2023-10-06 11:33:23 -07:00
James Zern
68e271354e webp-container-spec: reorder example chunk layout
place the unknown 'XYZW' chunk at the end of the file to agree with the
order given by the 'Extended File Format' section.

Change-Id: I5cec5a61069a03f3487f5f9ff9209f5ead6de24c
2023-09-01 15:00:53 -07:00
James Zern
0a2cad5115 webp-container-spec: move terms from intro section
to 'Terminology & Basics'

Change-Id: Iec9923086a2d339f12025c55da53b1e8a6919380
2023-07-27 16:18:57 -07:00
James Zern
fe80fbbd6b webp-container-spec: add some missing commas
The serial comma change is based on the Chicago Manual of Style
(CMOS), 17th edition.

Change-Id: I642d6eb87492bb671869b25415c59b96b749c798
2023-06-12 22:03:01 -07:00
James Zern
7f75c91ced webp-container-spec: fix location of informative msg
preprocessing bits are informative, not the filtering bits.

since:
391f9db9 Ordering of description of bits in container spec

Change-Id: I1c0da963074ce9cf4d33a13b4b36c9421b3e3b9d
2023-06-06 22:09:41 -07:00
James Zern
f6499943c4 webp-container-spec: consistently quote FourCCs
from the AUTH48 portion of the RFC review process

Change-Id: I3aad4b32c95517735e98ffa0120228ee24be6a4d
2023-06-06 18:47:20 -07:00
James Zern
49918af32b webp-container-spec: minor wording updates
Mostly grammatical and addition/subtraction of commas from the AUTH48
portion of the RFC review process.

The serial comma changes are based on the Chicago Manual of Style
(CMOS), 17th edition.

Change-Id: Ic75abf2e53e09c8a849e28e9c40e16c127515287
2023-06-05 18:26:34 -07:00
James Zern
15b365083d doc/webp-container-spec: rm future codec comment
From the compression standpoint the file format is fixed at this point.

Change-Id: I788fcf7106e4840bf2f9950dfb099a7bab88b3bf
2023-05-26 15:48:31 -07:00
James Zern
1de35f476b doc/webp-container-spec: don't use 'currently'
Provide examples of formats that WebP performs better than.

https://developers.google.com/style/timeless-documentation

Change-Id: I4ead60be349d8650478788484989bde9ff18f6b6
2023-05-26 15:48:26 -07:00
James Zern
bb06a16ed1 doc/webp-container-spec: prefer present tense
https://developers.google.com/style/tense

Change-Id: I0cd4e1431cddc340adf5634c07f0c60635b3d4f2
2023-05-26 15:48:23 -07:00
James Zern
7acb6b829a doc/webp-container-spec: avoid i.e. & e.g.
Using 'that is' or 'for example' is recommended:
https://developers.google.com/style/abbreviations#dont-use

Change-Id: I25b45f5b41687dfbd25a0fbea4978d6bc8e44ad2
2023-05-26 15:48:12 -07:00
James Zern
d8ed8c117c webp-container-spec: normalize section title case
Use 'title case' as recommended in RFC 7322 (Section 3.4 Capitalization)

Bug: webp:448
Change-Id: I9762402499eb58acbe9ccb75f4f8d2b9c3e9b26b
2022-11-21 10:53:13 -08:00
James Zern
5097ef6255 webp-container-spec,cosmetics: grammar/capitalization
Bug: webp:448
Change-Id: I8b5e218df95436b6b8b2ecc751c70015d46fe7a0
2022-11-17 19:13:39 -08:00
James Zern
017cb6fa94 webp-container-spec,cosmetics: normalize range syntax
this makes the syntax in this document consistent with
webp-lossless-bitstream-spec.txt

[N-M] -> [N..M]

Bug: webp:448
Change-Id: Iebf39eefb7d3c081a3d10e2804ee215c3aed6b79
2022-11-17 18:13:32 -08:00
James Zern
83270c7f89 webp-container-spec: add prose for rendering process
this is given in addition to the pseudocode, which has been corrected in
the process

based on comments in:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I96bc063c2a71572ff61609a731a9c4e8edc2b971
2022-10-13 19:34:54 -07:00
James Zern
73b19b64fd webp-container-spec: note reserved fields MUST be ignored
based on comments in:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I45880467d8955389a2ef657beca9d734da223457
2022-10-13 19:34:54 -07:00
James Zern
dfd32e4592 webp-container-spec: remove redundant sentence
in the note regarding metadata the possibility of multiple XMP/EXIF
chunks was already covered in the previous sentences.

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I6ee938e4d95bda1b144d3175fbf9f9296cf23352
2022-10-13 19:34:54 -07:00
James Zern
8a6185dd27 doc/webp-*: fix some punctuation, grammar
based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I0a410b28b7b62fb4552ea3db444743be61469fe8
2022-10-13 19:34:54 -07:00
James Zern
3ed2b27517 webp-container-spec: clarify background color note
replace ...a transparency value (alpha)... with clearer text

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I79157b669c4317ebfc4f8434ee38f2666d1559ec
2022-10-11 15:05:33 -07:00
James Zern
951c292d12 webp-container-spec: come too late -> out of order
based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: Ie32d5500f3966b3c9f910675fb11d8a2cc60de3c
2022-10-11 15:05:33 -07:00
James Zern
902dd78762 webp-container-spec: prefer hex literals
to ABNF-style values; this makes the doc more consistent with
doc/webp-lossless-bitstream-spec.txt.

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_lars-eggert

Bug: webp:448
Change-Id: I751cf0b7f728866ae663beb06e6352e5b3d848b2
2022-10-11 15:05:33 -07:00
James Zern
a8f6b5ee94 webp-container-spec: change SHOULD to MUST w/ANIM chunk
based on comments in:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_paul-wouters

Bug: webp:448
Change-Id: I9464dbbd734f1b78b287139eff13b1db8814c8d9
2022-10-11 15:05:33 -07:00
James Zern
1dc594352f webp-container-spec: add unknown fields MUST be ignored
based on comments in:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_paul-wouters

Bug: webp:448
Change-Id: I1eccb573b536f931b123261662efad7f92700500
2022-10-11 15:05:33 -07:00
James Zern
280a810f2a webp-container-spec: make padding byte=0 a MUST
this is consistent with the RIFF specification.

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_robert-wilton

Bug: webp:448
Change-Id: I7a09177c9ea001b2e8759dcc5102242864c78105
2022-10-11 15:05:33 -07:00
James Zern
41f0bf680b webp-container-spec: update note on trailing data
clarify that the data is after the size specified by the file size in
the header; an alternate way to read the previous statement was that the
data was after the 'WEBP' fourcc.

based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_robert-wilton

Bug: webp:448
Change-Id: I7c5c5440a94cb817da51fe07d1ccf45d6af0f001
2022-10-11 15:05:33 -07:00
James Zern
6bdd36dbe7 webp-container-spec: clarify Chunk Size is in bytes
based on comments from:
https://datatracker.ietf.org/doc/draft-zern-webp/ballot/#draft-zern-webp_robert-wilton

Bug: webp:448
Change-Id: Idc874e5fa04d3cd122d31b87e833bf9f30ec9d05
2022-10-11 15:05:33 -07:00
James Zern
fcbc2d78ab Merge "doc/*.txt: restrict code to 69 columns" into main 2022-08-05 22:03:51 +00:00
James Zern
7a0a9935ed doc/*.txt: restrict code to 69 columns
some renderers may limit output to 72 and use a 3 space indent; this
avoids overflowing into the margin

Change-Id: Iaf4e8b71be27ef00fccd1d82b79bf96c01040f10
2022-08-04 19:35:24 -07:00
James Zern
c040a615b1 webp-container-spec.txt: normalize fourcc spelling
fourcc -> FourCC as it's defined in the terminology

Change-Id: I49e3a5aaba525b295701d8aac7b1700c4003ca77
2022-08-04 11:47:22 -07:00
James Zern
8a4576ce26 webp-container-spec.txt: replace & with &
this conversion is handled by markdown processors

Change-Id: Ic679e40fcea577784deb8b455911bf1f201f2011
2022-08-03 11:12:23 -07:00
James Zern
5b87983ad0 webp-container-spec.txt: make reserved 0 values a MUST
these were intended as an extension point, but in this version of the
spec they're not defined. if they ever were used leaving them as SHOULD
could result in a source of incompatibility.

Change-Id: I1376ab7abe7d955ae335106f2faebc217dac77cd
2022-08-02 15:14:11 -07:00
James Zern
1a64a7e649 webp-container-spec.txt: clarify some SHOULDs
for compatibility SHOULDs are left as is with some additional
description given of behavior if the recommendation is ignored.

Change-Id: I7a25b1a6fd9f9594390c30fce3af5ca17c3158c0
2022-08-02 13:12:27 -07:00
James Zern
bec2c88a11 webp-container-spec.txt: move ChunkHeader to terminology
this avoids presenting it in the description of a chunk where it could
appear it was defining an element of the diagram

Change-Id: I51b2c2a0dcecb4fc130711ad37c884a434920ecd
2022-08-02 12:46:53 -07:00
James Zern
c9359332a3 webp-container-spec.txt: clarify 'VP8 '/'XMP ' fourccs
Note the fourth character is an ASCII space to avoid confusion.
Also update the FourCC definition to mention that they're case
sensitive.

Change-Id: I87d0cbcf06e7c25bf2b33419b4c8c891adb82a8a
2022-08-01 18:51:35 -07:00
James Zern
70fe3063a5 webp-container-spec.txt: rightsize table entries
Use the correct number of lines for fixed width entries like
ChunkHeader(). ':' is used instead of '|' for variable length entries.

Bug: webp:546
Change-Id: I6ec60af674c0777d5ea6ae99c8aa3c7854ddd9f9
Fixed: webp:546
2022-08-01 18:49:43 -07:00
James Zern
ddbf3f3f2a webp-container-spec.txt: update 'key words' text
RFC 2119 was updated by RFC 8174; use the text from there

+ change INFORMATIVE to informative to avoid confusion with the key
  words in the RFCs

Change-Id: I0a3fe9dc48d284e7ac95633896ffb855ecd1a229
2022-08-01 18:42:21 -07:00
Maryla
54e61a3864 Markdownify libwebp docs and reorganize them.
Break the main README into into multiple pages in the doc/ directory,
except for the tests, swig and webp_js docs which are in the corresponding
directories.
The webp mux doc is merged into the API doc and the tools doc.

Change-Id: Ia407617dd88094f4662841d37947cfef80799914
2022-02-15 15:31:56 +00:00
James Zern
88b6a396f1 webp-container-spec.txt,cosmetics: normalize formatting
- prefer Exif to EXIF when not referring to the chunk
- normalize use of code format for canvas / frame width & height

Change-Id: I7fc9e87baeb5d8e719274680ce621dcb078a985f
2022-01-25 18:36:36 -08:00
James Zern
b6f756e82b update http links
- prefer https

- metadataworkinggroup.org/com seem to be offline; the web archive link
  was obtained from exiftool: https://exiftool.org/TagNames/MWG.html

- fix kramdown link, rubyforge has been gone a long time

- fix png/zlib links

Bug: webp:544
Bug: b/202302177
Change-Id: Id69de4553e7baf00393f12a2c1acb262443a1a93
2021-11-23 10:13:40 -08:00
James Zern
8f5cb4c18e update rfc links
to https://datatracker.ietf.org/doc/html/... the http tools.ietf.org
links redirect here sometimes, in other cases they 404.

Bug: webp:544
Change-Id: I900972070d6c5659c45a86a89e78b870f42fe5bc
2021-11-17 11:03:35 -08:00
James Zern
21d24b4c08 webp-container-spec.txt: remove 'experimental' markers
unknown chunks as a group are well defined in the text

+ remove the Note about stable features as it matched the list given;
there are no WIP features for the format

Change-Id: I11a4de39f9d203b815879f0e9dea9c45b2ae6ff6
2021-10-22 12:17:59 -07:00
James Zern
1f5791398c cosmetics: remove use of 'sanity' / 'master'
replace with more inclusive terms or remove the comment entirely if the
meaning was already clear.

Bug: webp:507
Change-Id: Ica3bbf751ebf79f6668df6e6209af770248ff4ca
2021-05-21 10:38:40 -07:00
James Zern
71c39a06c8 webp-container-spec: correct frame duration=0 note
the interpretation of a 0 duration depends on the implementation;
merging of multiple frames isn't guaranteed, some may enforce a minimum
duration.

BUG=webp:380

Change-Id: Idf592049d2092e4cc5cfb2e4c59ddbc91bd52f9c
2018-04-20 15:23:12 -07:00
Urvang Joshi
585d93dbba Container spec: clarify ordering of ALPH chunk.
Reported by user: https://code.google.com/p/webp/issues/detail?id=255

Change-Id: I9c027ea828d5a367b317744fad7607a16ed52fa5
2015-07-22 11:55:49 -07:00
James Zern
f0486968ba doc/webp-container-spec: update repo browser link
gerrit.chromium.org is deprecated, use chromium.googlesource.com.

Change-Id: Iaa6d6d18798dbd8cce908988287387f5cb8e8e64
2015-04-29 23:31:34 -07:00
James Zern
b510fbfe3b doc/webp-container-spec: note MSB order for chunk diagrams
addresses question in issue #241

Change-Id: Iff6a172d5822f6ec8b9bc0951a1c9cd3f98c9251
2015-02-12 20:18:58 -08:00
James Zern
e7d3df2314 doc/webp-container-spec: cosmetics
partially normalize indent, vertical whitespace and capitalization with
the copy used on developers.google.com/speed/webp

Change-Id: I8044418eeb9eaf5bd5c799675c74f6f845d503d6
2015-02-06 15:18:32 -08:00
James Zern
560394798f webp-container-spec: clarify background clear on loop
at the beginning of the loop there's an implicit clear of the entire
canvas to the background (or application defined) color. this avoids
adding the final composited frame to the first.

Change-Id: Ia3a52cf4482c6176334a5c9c99a0ddd07d1776e7
2015-02-04 18:07:00 -08:00
James Zern
a66e66c79d webp-container-spec: remove references to fragments
this portion of the format was never finalized

Change-Id: I80aa1b27457a0e52b047c7284df2f58b181ca5d8
2014-12-22 11:51:29 -05:00
Urvang Joshi
d5bad03328 Animated WebP: add "do no blend" option to spec
Marking certain frames as "do not blend" helps avoiding alpha-blending
at decode/render time.

It also helps inserting I-frames (frames which can be independently
decoded) into the animation.

Change-Id: Iaa222805db88d2f1c81104ce9d882e7c7ff8cfdb
2013-08-14 11:50:15 -07:00