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doc: tile/alpha corrections

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- the tile chunk size does not include the alpha or vp8 chunks that
  follow
- remove 'experimental' note from alpha section
- drop an unused term from the terminology section

Change-Id: I46f0fd610bbce579446e19339c3458dddfb595f7
This commit is contained in:
James Zern 2012-04-24 17:43:06 -07:00
parent 1349edade1
commit 5249e94a22
1 changed files with 2 additions and 14 deletions
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16
doc/webp-container-spec.txt
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@ -121,10 +121,6 @@ _ChunkHeader('ABCD')_
chunks, where 'ABCD' is the fourcc for the chunk. This element's chunks, where 'ABCD' is the fourcc for the chunk. This element's
size is 8 bytes. size is 8 bytes.
_chunk of type_
: A chunk with a tag "ABCD".
: Note that, in this specification, all chunk tag characters are in : Note that, in this specification, all chunk tag characters are in
file order, not in byte order of a uint32 of any particular file order, not in byte order of a uint32 of any particular
architecture. architecture.
@ -413,8 +409,6 @@ Notes for frames containing VP8 data:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tile Canvas Y | | Tile Canvas Y |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tile Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Tile Canvas X: 32 bits (_uint32_) Tile Canvas X: 32 bits (_uint32_)
@ -424,12 +418,8 @@ Tile Canvas Y: 32 bits (_uint32_)
: Y coordinate of the upper left corner of the tile. : Y coordinate of the upper left corner of the tile.
Tile Data: _Chunk Size_ - `8` bytes
: VP8 data.
This chunk contains information about a single tile and describes the This chunk contains information about a single tile and describes the
bitstream chunk that follows it. (optional) alpha chunk and bitstream chunk that follows it.
Notes for tiles containing VP8 data: Notes for tiles containing VP8 data:
@ -486,9 +476,7 @@ Either **ALL or NONE** of the tiles must contain this chunk.
The alpha channel can be encoded either losslessly or with lossy The alpha channel can be encoded either losslessly or with lossy
preprocessing (quantization). After the optional preprocessing, the preprocessing (quantization). After the optional preprocessing, the
alpha values are encoded with a lossless compression method like alpha values are encoded with a lossless compression method like
zlib. Work is in progress to improve the compression gain further by zlib.
exploring alternate compression methods and hence, the bitstream for
the Alpha-chunk is still experimental and expected to change.
#### Color profile #### Color profile