Commit Graph

76 Commits

Author SHA1 Message Date
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
Pascal Massimino
13ae011e4c doc: use two's complement explicitly for uint8->int8 conversion
BUG=webp:225

Change-Id: I6bad131e275dbd992484e95a1b834010121281b8
2016-09-05 10:57:56 -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
Pascal Massimino
d7167ff7ce Amend the lossless spec according to issue #205, #206 and #224
http://code.google.com/p/webp/issues/detail?id=205 <- Select()
http://code.google.com/p/webp/issues/detail?id=206 <- out-of-bound colormap index
http://code.google.com/p/webp/issues/detail?id=224 <- version number MUST be 0

Change-Id: I56a575529862dfc8ad189ddcfc47ef59a58f273d
2014-09-18 08:21:02 +02:00
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
Lou Quillio
c606182edd webp-container-spec: Tighten language added by last
Change-Id: Id7719ba7f1ddfd7b54a1985771b2811318a7c0d7
2013-07-09 18:45:39 -07:00
Urvang Joshi
5e9675329c Container spec: a clarification on background color.
Change-Id: Ifeb565bd162abfa03dfcbf8b576657fe83956a6c
2013-06-20 17:38:08 -07:00
Urvang Joshi
403bfe820c Container spec: Clarify frame disposal
- Add a note that disposal only applies to the frame rectangle
- Add the formula for alpha-blending.
- Note that alpha-blending would occur for the common rectangle
- Also note the case when both color profile and disposal are
present.

Change-Id: I214787dd64453edf3b0cdaff3951015281a32ee4
2013-03-29 11:42:17 -07:00
James Zern
3e7a13a008 Merge "Container spec: clarify the background color field" into 0.3.0 2013-03-26 17:38:07 -07:00
James Zern
14af77452b container doc: add a note about the 'ANMF' payload
this consists of padded chunks, so ANMF should require none

Change-Id: I5dff623b56d8a466dc9be03ee87d1d2d19efc088
2013-03-26 17:25:27 -07:00
Urvang Joshi
cc635efa01 Container spec: clarify the background color field
Change-Id: I03f634cbd147c2851eb06ddbc7b1014e04e21038
2013-03-26 17:22:18 -07:00
James Zern
e3e339497e container doc: move RIFF description to own section
- remove some little used terms
- condense file header description
- add description of FourCC

Change-Id: Ia873652f41789811f3fb2ec97182a068ac727961
2013-03-26 17:16:12 -07:00
Urvang Joshi
d1e21b13b7 Remove 'status: experimental' from container spec
For features that are to be released in v0.3.0.

Change-Id: Ib8961f8cde0474aeaad5796bd0821db812edffcd
2013-03-13 18:16:30 -07:00
Urvang Joshi
8425aaee8f Formatting fixes in lossless bitstream spec
- Escape brackets for which kramdown was generating a warning.
Note: This only changes this source file; output HTML would look exactly
the same.
- Also write '5' in words ('five').

Change-Id: I472a03c090a12eb7520719ea463469b36a2736b9
2013-01-18 14:35:47 -08:00
Urvang Joshi
f01c2a538c WebP-lossless spec clarifications:
- Clarify the BNF using 'Huffman code groups' and 'Huffman code group'.
- Introduce same terminology in 'Interpretation of meta Huffman codes'.
- Make explicit mention of what is the number of Huffman code groups,
  number of Huffman codes and the relation between the two.

Change-Id: I07aa9b62c1d464cd25dc02ac1a68d338b575bdc2
2013-01-17 15:19:09 -08:00
Urvang Joshi
1f075f89b0 Lossless spec corrections/rewording/clarifications
- Correct BNF for 'predictor-image' and 'color image'
- Correct some references to 'br', 'VP8LReadBits' and 'ReadStream'
- Correct value ranges in distance mapping table.
- Rewrite section 4 (some rearrangement, rewording, adding context etc).
- Similarly, rewrite section 5.

Change-Id: If487490c2553b3f7982b9fcca68d98bab5017e3c
2012-12-20 10:44:42 -08:00
Urvang Joshi
d82a3e3391 More corrections/clarifications in lossless spec:
- Rectify a few BNF descriptions
- Corrections in "Decoding Flow of Image Data" section:
  1. The sequence in case of "S < 256" should be green, red, blue, alpha.
  2. In case of "S >= 256 + 24", the index should be "S - (256 + 24)".
- Provide more description to clarify "Decoding Flow of Image Data" section.
- Some cosmetics: use '1's instead of '1, 2, 3...' sequence, as kramdown takes
  care of sequencing.

Change-Id: I2b76caf72f67aae813522dc1a4115f8ec8ea6db7
2012-12-17 11:40:23 -08:00
Urvang Joshi
bcec339b01 Lossless bitstream clarification:
Clarify what the pixels of a color transform image are.

Change-Id: I720248b5417857468d54952440cf1bae6c091042
2012-12-12 14:03:44 -08:00
Urvang Joshi
931bd516b8 lossless bitstream: block size bits correction
The color transform block size is stored as 3 bits, not 4.
Fixed the description. The code snippet is already correct.

Change-Id: I830d848b54c121cb5426ca06853a3f1184fd9a31
2012-12-05 13:38:05 -08:00
Pascal Massimino
e4fc4c1c63 lossless bitstream: block size bits correction
The prediction block size is stored as 3 bits, not 4.
Fixed the description. The code snippet is already correct.

Change-Id: Iaa66a7e9817b58a2557c9a71c2231cc400b6ae4d
2012-12-05 00:01:28 -08:00
Urvang Joshi
6523e2d41d WebP Container:
annotate specific sections as experimental

Change-Id: If43222cef1c4fc2a8164b5f6ca4e89033379757d
2012-11-15 11:01:41 -08:00
Urvang Joshi
a7305c2ef0 Clarification for unknown chunks
clarify that writers *may* modify unknown chunks if they specifically
intend to do so.

Change-Id: I8348df2ec84648201ea781c7bfffd1f36eb3c8e5
2012-11-13 10:41:13 -08:00
Urvang Joshi
4c4398e2d5 Refine WebP Container Spec wrt unknown chunks.
Change-Id: Ibe950ab7afb2a7349f61c6fb81d587fba9ff27b6
2012-11-12 14:32:44 -08:00
Urvang Joshi
52ad1979d2 Animation specification in container spec
Change-Id: I3cb1d994a460d9a712998ca1045bf6bc7d953c04
2012-11-05 13:29:23 -08:00
Urvang Joshi
001b930219 Image fragment specification in container spec
Change-Id: If8cad296738465df4327dfb6b44efa7e0356070e
2012-11-02 15:37:49 -07:00
Urvang Joshi
391f9db9fa Ordering of description of bits in container spec
The description of bits in a byte should be from MSB to LSB

Change-Id: I50f2dfbb79b33eb434a771cca252c5d0f81fc71e
2012-11-02 15:27:37 -07:00
Urvang Joshi
d57357762a Metadata specification in container spec
Change-Id: I4b76697efb160145ffef3fd9df9905544c4e8792
2012-11-02 15:14:47 -07:00
Urvang Joshi
af6f0db291 Color profile specification in container spec
Change-Id: I53f849c7d93e1cdc971dda1fffd8f359f40607d3
2012-11-01 11:16:29 -07:00
Jyrki Alakuijala
d03b250369 fixing the findings by Frederic Kayser to the bitstream spec
Change-Id: I4bcc428412dd4c21675d90159771e2e0b338ecf3
2012-07-18 22:47:11 -07:00
Lou Quillio
4e2e0a8cac Doc: container spec text tweaks
Change-Id: I8e29f1c814b0c8f6aa268562d8653989caaf281d
modified:   doc/webp-container-spec.txt
2012-07-18 16:38:50 -07:00
James Zern
6431a1ce3d doc: remove non-finalized chunk references
tiles, animation, etc.

Change-Id: Ie83135be576f516fe475c7be21171f9d12a17ce4
2012-07-13 12:33:49 -07:00
James Zern
85bff2cdbe Merge "doc: correct lossless prefix coding table & code" 2012-07-13 11:12:14 -07:00
James Zern
20ead3290f doc/webp-container-spec: light cosmetics
- provide anchor links to the bitstream chunks referenced in the
  extended format section
- remove some unnecessary parenthetical notation and add some
  consistency to various chunk element definitions

Change-Id: Ifd946fee81b36e4e555399555a2a58c853fdc3b7
2012-07-12 19:19:39 -07:00
pascal massimino
45b8272c31 Merge "restore authorship to lossless bitstream doc" 2012-07-11 13:56:10 -07:00
James Zern
06ba05909e restore authorship to lossless bitstream doc
lost in port from pdf

Change-Id: I17bad348577be9818c036e557a0beba63ffcc689
2012-07-11 13:46:00 -07:00
Pascal Massimino
44a09a3ccd add missing description of the alpha filtering methods
Change-Id: Id7bdf5e30121ce5d610b7fa00f64bcd2d7bed2bf
2012-07-10 19:50:30 -07:00
Urvang Joshi
135ca69eb7 WebP Container Spec:
Clarify that a file must contain at least one frame.

Change-Id: I7ecc97084498adc108275585d0c7d0aaa9f5c6ed
2012-07-04 17:28:17 +05:30
Pascal Massimino
7f22bd2596 check limit of width * height is 32 bits
Update the RIFF-specs file too

Change-Id: I113a7e25da2f7a19c1344c1dc5d496127cfe2596
2012-07-03 05:42:13 -07:00
James Zern
61c9d161d5 doc: correct lossless prefix coding table & code
extra bit counts and literal distance return value

Change-Id: I290e3ee8900469503a323f87e9dbb8ca5cb4afc7
2012-07-01 14:10:32 -07:00
Urvang Joshi
97649c8f6b Mux: Allow only some frames/tiles to have alpha.
And related const fixes.

Change-Id: I79f6f1b9f8c6faac8cc4ef24b58edff6d90de045
2012-06-29 17:17:19 +05:30
James Zern
c963482124 doc: remove lossless pdf
superseded by webp-lossless-bitstream-spec.txt

Change-Id: I5f233d4c3c2fa048a180db950ad4319ffdb9bced
2012-06-22 15:25:03 -07:00
Urvang Joshi
7f8472a610 Update the WebP Container Spec.
- Add details about the VP8L chunk support.
- Also add new example bitsteams containing VP8L chunk.
- Add back a section describing the VP8 chunk.
- Restrict some fields to 16 or 24 bits instead of 32 bits.
- Fields whose values are always positive are stored 1-based
instead of 0-based.
- Unknown chunks can only occur at certain places in the file.
- Remove the restriction for some fields to be divisible by 32 or 16.
  Instead they are restricted to be even.
- Add a restriction for (canvas_width * canvas_height) product.
- Add 3 bits for rotation & symmetry in VP8X flags.
- Add some new example layouts.
- Add/clarify some nitty-gritties throughout the doc.
- Use the terms frame/tile more consistently and logically.
- Update related TODOs.

Change-Id: I611c1f58ecc3ee87546ca31bad1609376fad251e
2012-06-21 16:04:58 -07:00
Lou Quillio
b7ac19fec9 Add kramdown version information to README
Example kramdown command line to apply syntax highlighting requires
kramdown latest. Command is slightly different for earlier versions.

modified:   doc/README

Change-Id: Icda1197436b5c5ed936ceff53c1dc51aa4ce409b
2012-06-20 14:17:36 -07:00
Lou Quillio
04e33f17de Edit for consistency, usage and grammar.
Substantial edit, though less than 100% thorough.  This
makes changes that are clearly safe, but avoids others
where my domain knowledge is incomplete and accuracy
might be compromised.

modified:   doc/webp-lossless-bitstream-spec.txt

Change-Id: I89361a2e1157b8d2e44a8b4f4603f65833f0c1e6
2012-06-20 10:08:53 -07:00
Lou Quillio
9aa34b3438 Manually number "chapters," as chapter numbers are used in the narrative.
modified:   doc/webp-lossless-bitstream-spec.txt

Change-Id: Ice662960ff988a6ff577a8ca5a594e14ba69d4de
2012-06-15 14:54:19 -07:00