No further experiments are to be expected, so this is quite the
final format so far, pending supplemental feedbacks.
Change-Id: I2a3de025c90b7bb5fdd8792b2b2ccdc2e3753f56
may be useful later for instance to bypass some code
if we know we don't use the Bundle+ColorMap transform.
Change-Id: I9dc70d18165b2363ad9ede763684ef3d8eba5903
we vary linearly lossless-method between 0 and 6,
and lossless-quality between 50 and 100, so that encoding
speed can go from 'quite fast' to 'rather slow'.
Impact on size is moderate, but visible.
Change-Id: I0b7917e7170eb50258afb1a4e248028cd9e9207d
- Make sure alpha flag is set in case of a lossless file with VP8X chunk.
The semantic of ALPHA_FLAG changes with this: it means the images
contain alpha (rather than ALPH chunk in particular).
- Update the mux container spec to add 1-line description of alpha
flag.
- Rename "HasLosslessImages()" to "MuxHasLosslessImages()", and other
similar function renames.
- Rename FeatureFlags to WebPFeatureFlags
- Elaborated a comment for a special case.
- A misc comment fix.
Change-Id: If212ccf4338c125b4c71c10bf281a51b3ba7ff45
Defining LOCAL_ARM_NEON = true can result in neon instructions being
used in portions unprotected by the cpu check.
This changes defines a WEBP_USE_NEON/WEBP_ANDROID_NEON pair similar to
the SSE2 code and MSVC.
Change-Id: Ifac010b06e42c73d5aca529baa2198c6796674bd
This saves ~26 bytes of headers.
* introduce new VP8LDecodeAlphaImageStream() for decoding
* use VP8LEncodeStream() for encoding
* refactor code a bit
still TODO: make the alpha-quality/enc-method user-configurable
Change-Id: I23e599bebe335cfb5868e746e076c3358ef12e71
Limit the overall number of transformations to 4 and disallow any
duplicate transform for decoding an image.
Change-Id: Ic4b0ecd553db96702e117fd073617237d95e45c0
this allows later customization of data output method.
No perf diff observed, even if ProcessRows is no longer inlined.
Change-Id: I6933a3612a9cf6c108cf2776dfde0ae80c6c07c0
+ small opportunistic fixes:
* allow NULL decoded_data to be passed to DecodeStream
and clarity (with assert()) when to do so
* AllocateAndInitRescaler() was already setting error status,
as it should. No need to do it at caller's site
Change-Id: I30867e596564a7f459a0d1ddbf6f5d312414b7fd
* RIFF header is omitted
* rename NewVP8LEncoder and DeleteVP8Encoder
* change the signature to take a "const WebPPicture*"
(it was non-const just because we were setting some error potentially)
* made the pic_ field const in VP8LEncoder too.
* trap the bitwriter::error_ too
* simplify some signatures to take WebPPicture* instead
of unneeded VP8LEncoder*
VP8LEncodeStream() will be called directly to compress alpha channel
header-less.
Change-Id: Ibceef63d2b3fbc412f0dffc38dc05c2dee6b6bbf
This is a border-case situation: the picture is not const, because
we're change its error status. But taking it non-const forces
the caller to carry a non-const picture all around the code just
in case (0.00001% of the time?) something bad happen.
This pretty much the same as making all objects non-const because
we'll eventually call delete or free() on them, which is quite a
non-const operation. Well... Better allow constness enforcement for
the remaining 99.9999% of the code.
Change-Id: I9b93892a189a50feaec1a3a518ebf488eb6ff22f
now, we only use 2 bits for the filtering method, and 2 bits
for the compression method.
There's two additional bits which are INFORMATIVE, to specify
whether the source has been pre-processed (level reduction)
during compression. This can be used at decompression time
for some post-processing (see DequantizeLevels()).
New relevant spec excerpt:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ChunkHeader('ALPH') |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Rsv| P | F | C | Alpha Bitstream... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Compression method (C): 2 bits
: The compression method used:
* `0`: No compression.
* `1`: Backward reference counts encoded with arithmetic encoder.
Filtering method (F): 2 bits
: The filtering method used:
* `0`: None.
* `1`: Horizontal filter.
* `2`: Vertical filter.
* `3`: Gradient filter.
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
: SHOULD be `0`.
Alpha bitstream: _Chunk Size_ - `1` bytes
: Encoded alpha bitstream.
This optional chunk contains encoded alpha data for a single tile.
Either **ALL or NONE** of the tiles must contain this chunk.
The alpha channel data is losslessly stored as raw data (when
compression method is '0') or compressed using the lossless format
(when the compression method is '1').
Change-Id: Ied8f5fb922707a953e6a2b601c69c73e552dda6b
will be called by alpha post-processing, although doing nothing for now.
Gradient smoothing would be nice-to-have here. Patch welcome!
Change-Id: I534cde866bdc75da22d0f0a6d1373c90e21366f3
* Method #1 is now calling the lossless encoder on the alpha plane.
Format is not final, it's just a first draft. We need ad-hoc functions.
* removed now useless utils/alpha.*
* added utils/quant_levels.h instead
* removed the TCoder code altogether
Change-Id: I636840b6129a43171b74860e0a0fc5bb1bcffc6a
- Separate out 'CHUNK_INDEX' from 'TAG_ID' (this is to help with the
situation where two different tags - "VP8 " and "VP8L" can have the
same TAG_ID -> IMAGE_ID).
- Some internal methods now take 'CHUNK_INDEX' param instea of 'TAG_ID'
as appropriate.
- Add kChunks[] entry for lossless.
- Rename WebPMuxImage.vp8_ --> WebPMuxImage.img_
- SetImage() and AddFrame/Tile() infer whether the bitstream is a
lossless one based on LOSSLESS_MAGIC_BYTE. The correct tag is stored
based on this.
Also, handle the case when GetVP8Info/GetVP8LInfo() fails.
Change-Id: I6b3bc9555cedb791b43f743b5a7770958864bb05
-> lot of simplifications ensue and we should be able to get rid of
ClearHuffmanTreeIfOnlyOneSymbol() too, in a subsequent patch.
Change-Id: Ic4c51d05e4b1970e37f94ffd85fae6a02e4a6422
Allocate big chunk of memory in GetHuffBitLengthsAndCodes, instead of allocating in a loop.
Also fixed the potential memleak.
Change-Id: Idc23ffa306f76100217304444191a8d2fef9c44a
The size written in VP8L header should be without padding.
(Also clarified this code using consts).
Change-Id: Ic6583d760c0f52ef61924ab0330c65c668a12fdc
When we are at end-of-stream, but haven't decoded all pixels, we should
return an error.
Also remove an obsolete TODO.
Change-Id: I3fb1646136e706da536d537a54d1fa487a890630
