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webp-container-spec.txt: clarify 'VP8 '/'XMP ' fourccs

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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
This commit is contained in:
James Zern 2022-08-01 18:50:17 -07:00
parent 70fe3063a5
commit c9359332a3
1 changed files with 6 additions and 1 deletions
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7
doc/webp-container-spec.txt
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@ -84,7 +84,8 @@ _uint32_
_FourCC_ _FourCC_
: A _FourCC_ (four-character code) is a _uint32_ created by concatenating four : A _FourCC_ (four-character code) is a _uint32_ created by concatenating four
ASCII characters in little-endian order. ASCII characters in little-endian order. This means 'aaaa' (%x61.61.61.61) and
'AAAA' (%x41.41.41.41) are treated as different _FourCCs_.
_1-based_ _1-based_
@ -203,6 +204,8 @@ VP8 data: _Chunk Size_ bytes
: VP8 bitstream data. : VP8 bitstream data.
Note the fourth character in the 'VP8 ' fourcc is an ASCII space (%x20).
The VP8 bitstream format specification can be found at [VP8 Data Format and The VP8 bitstream format specification can be found at [VP8 Data Format and
Decoding Guide][vp8spec]. Note that the VP8 frame header contains the VP8 frame Decoding Guide][vp8spec]. Note that the VP8 frame header contains the VP8 frame
width and height. That is assumed to be the width and height of the canvas. width and height. That is assumed to be the width and height of the canvas.
@ -714,6 +717,8 @@ XMP Metadata: _Chunk Size_ bytes
: image metadata in XMP format. : image metadata in XMP format.
Note the fourth character in the 'XMP ' fourcc is an ASCII space (%x20).
Additional guidance about handling metadata can be found in the Additional guidance about handling metadata can be found in the
Metadata Working Group's [Guidelines for Handling Metadata][metadata]. Metadata Working Group's [Guidelines for Handling Metadata][metadata].