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doc/*.txt: restrict code to 69 columns

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some renderers may limit output to 72 and use a 3 space indent; this
avoids overflowing into the margin

Change-Id: Iaf4e8b71be27ef00fccd1d82b79bf96c01040f10
This commit is contained in:
James Zern 2022-08-04 19:28:16 -07:00
parent 835392393b
commit 7a0a9935ed
2 changed files with 45 additions and 40 deletions
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10
doc/webp-container-spec.txt
View File

@ -511,7 +511,8 @@ Disposal method (D): 1 bit
if blend.A = 0 then
blend.RGB = 0
else
blend.RGB = (src.RGB * src.A +
blend.RGB =
(src.RGB * src.A +
dst.RGB * dst.A * (1 - src.A / 255)) / blend.A
~~~~~
@ -782,11 +783,12 @@ for loop = 0..loop_count - 1
else if subchunk.tag == "VP8 " OR subchunk.tag == "VP8L":
assert bitstream subchunks not found in 'Frame Data' earlier
frame_params.bitstream = bitstream_data
render frame with frame_params.alpha and frame_params.bitstream on
canvas with top-left corner at (frame_params.frameX,
render frame with frame_params.alpha and frame_params.bitstream
on canvas with top-left corner at (frame_params.frameX,
frame_params.frameY), using dispose method dispose_method.
canvas contains the decoded image.
Show the contents of the canvas for frame_params.frameDuration * 1ms.
Show the contents of the canvas for
frame_params.frameDuration * 1ms.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

31
doc/webp-lossless-bitstream-spec.txt
View File

@ -480,7 +480,8 @@ void InverseTransform(uint8 red, uint8 green, uint8 blue,
// color transform deltas
tmp_red += ColorTransformDelta(trans->green_to_red, green);
tmp_blue += ColorTransformDelta(trans->green_to_blue, green);
tmp_blue += ColorTransformDelta(trans->red_to_blue, tmp_red & 0xff);
tmp_blue +=
ColorTransformDelta(trans->red_to_blue, tmp_red & 0xff);
*new_red = tmp_red & 0xff;
*new_blue = tmp_blue & 0xff;
@ -920,7 +921,7 @@ int kCodeLengthCodes = 19;
int kCodeLengthCodeOrder[kCodeLengthCodes] = {
17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
};
int code_length_code_lengths[kCodeLengthCodes] = { 0 }; // All zeros.
int code_length_code_lengths[kCodeLengthCodes] = { 0 }; // All zeros
for (i = 0; i < num_code_lengths; ++i) {
code_length_code_lengths[kCodeLengthCodeOrder[i]] = ReadBits(3);
}
@ -1024,7 +1025,8 @@ Given a pixel (x, y) in the ARGB image, we can obtain the corresponding prefix
codes to be used as follows:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
int position = (y >> prefix_bits) * prefix_xsize + (x >> prefix_bits);
int position =
(y >> prefix_bits) * prefix_xsize + (x >> prefix_bits);
int meta_prefix_code = (entropy_image[pos] >> 8) & 0xffff;
PrefixCodeGroup prefix_group = prefix_code_groups[meta_prefix_code];
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -1090,8 +1092,8 @@ of pixels (xsize * ysize).
#### 7.2 Structure of Transforms
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<optional-transform> ::= (1-bit value 1; <transform> <optional-transform>) |
1-bit value 0
<optional-transform> ::=
(1-bit value 1; <transform> <optional-transform>) | 1-bit value 0
<transform> ::= <predictor-tx> | <color-tx> | <subtract-green-tx> |
<color-indexing-tx>
<predictor-tx> ::= 2-bit value 0; <predictor image>
@ -1111,32 +1113,33 @@ of pixels (xsize * ysize).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<spatially-coded image> ::= <color cache info><meta prefix><data>
<entropy-coded image> ::= <color cache info><data>
<color cache info> ::= 1 bit value 0 |
(1-bit value 1; 4-bit value for color cache size)
<color cache info> ::=
1 bit value 0 | (1-bit value 1; 4-bit value for color cache size)
<meta prefix> ::= 1-bit value 0 |
(1-bit value 1; <entropy image>)
<data> ::= <prefix codes><lz77-coded image>
<entropy image> ::= 3-bit subsample value; <entropy-coded image>
<prefix codes> ::= <prefix code group> | <prefix code group><prefix codes>
<prefix codes> ::= <prefix code group> |
<prefix code group><prefix codes>
<prefix code group> ::= <prefix code><prefix code><prefix code>
<prefix code><prefix code>
See "Interpretation of Meta Prefix Codes" to
understand what each of these five prefix codes are
for.
understand what each of these five prefix
codes are for.
<prefix code> ::= <simple prefix code> | <normal prefix code>
<simple prefix code> ::= see "Simple code length code" for details
<normal prefix code> ::= <code length code>; encoded code lengths
<code length code> ::= see section "Normal code length code"
<lz77-coded image> ::= ((<argb-pixel> | <lz77-copy> | <color-cache-code>)
<lz77-coded image>) | ""
<lz77-coded image> ::= ((<argb-pixel> | <lz77-copy> |
<color-cache-code>) <lz77-coded image>) | ""
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A possible example sequence:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<RIFF header><image size>1-bit value 1<subtract-green-tx>
1-bit value 1<predictor-tx>1-bit value 0<color cache info>1-bit value 0
<prefix codes><lz77-coded image>
1-bit value 1<predictor-tx>1-bit value 0<color cache info>
1-bit value 0<prefix codes><lz77-coded image>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[canonical_huff]: https://en.wikipedia.org/wiki/Canonical_Huffman_code