From 391f9db9fa35c0098ed1e6af745319f5fae6aab5 Mon Sep 17 00:00:00 2001 From: Urvang Joshi Date: Fri, 2 Nov 2012 15:27:37 -0700 Subject: [PATCH] Ordering of description of bits in container spec The description of bits in a byte should be from MSB to LSB Change-Id: I50f2dfbb79b33eb434a771cca252c5d0f81fc71e --- doc/webp-container-spec.txt | 52 ++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 26 deletions(-) diff --git a/doc/webp-container-spec.txt b/doc/webp-container-spec.txt index afca93f4..cdcad798 100644 --- a/doc/webp-container-spec.txt +++ b/doc/webp-container-spec.txt @@ -13,7 +13,7 @@ end of this file. WebP Container Specification ============================ -_Working Draft, v0.7, 20121101_ +_Working Draft, v0.7, 20121102_ * TOC placeholder @@ -291,28 +291,28 @@ Extended WebP file header: ... Canvas Height Minus One | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -Reserved (R): 2 bits +Reserved (Rsv): 2 bits : SHOULD be `0`. -XMP metadata (X): 1 bit +ICC profile (I): 1 bit -: Set if the file contains XMP metadata. - -EXIF metadata (E): 1 bit - -: Set if the file contains EXIF metadata. +: Set if the file contains an ICC profile. Alpha (L): 1 bit : Set if the file contains some (or all) images with transparency information ("alpha"). -ICC profile (I): 1 bit +EXIF metadata (E): 1 bit -: Set if the file contains an ICC profile. +: Set if the file contains EXIF metadata. -Reserved (Rsv): 2 bits +XMP metadata (X): 1 bit + +: Set if the file contains XMP metadata. + +Reserved (R): 2 bits : SHOULD be `0`. @@ -346,12 +346,18 @@ Future specifications MAY add more fields. |Rsv| P | F | C | Alpha Bitstream... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -Compression method (C): 2 bits +Reserved (Rsv): 2 bits -: The compression method used: +: SHOULD be `0`. - * `0`: No compression. - * `1`: Compressed using the WebP lossless format. +Pre-processing (P): 2 bits + +: These INFORMATIVE bits are used to signal the pre-processing that has +been performed during compression. The decoder can use this information to +e.g. dither the values or smooth the gradients prior to display. + + * `0`: no pre-processing + * `1`: level reduction Filtering method (F): 2 bits @@ -398,20 +404,14 @@ There are special cases for left-most and top-most pixel positions: location (x, 0) are predicted using the location (x-1, 0) on the left. -Pre-processing (P): 2 bits - -: These INFORMATIVE bits are used to signal the pre-processing that has -been performed during compression. The decoder can use this information to -e.g. dither the values or smooth the gradients prior to display. - - * `0`: no pre-processing - * `1`: level reduction - Decoders are not required to use this information in any specified way. -Reserved (Rsv): 2 bits +Compression method (C): 2 bits -: SHOULD be `0`. +: The compression method used: + + * `0`: No compression. + * `1`: Compressed using the WebP lossless format. Alpha bitstream: _Chunk Size_ - `1` bytes