Marking certain frames as "do not blend" helps avoiding alpha-blending
at decode/render time.
It also helps inserting I-frames (frames which can be independently
decoded) into the animation.
Change-Id: Iaa222805db88d2f1c81104ce9d882e7c7ff8cfdb
Also created variant VP8LPrefixEncodeBits that returns the
code & extra_bits only.
There's no impact on compression density and compression speed.
Change-Id: I2cafdd3438ac9270cd72ad9d57b383cdddfdfa4c
WebPDemuxPartial() returns NULL for both of the following cases:
- There was a parsing error.
- It doesn't have enough data to start parsing.
Now, one can differentiate between these two cases by checking the value
of 'state' returned by WebPDemuxPartial().
Change-Id: Ia2377f0c516b3fcfae475c0662c4932d2eddcd0b
Earlier, all lossless images were assumed to contain alpha.
Now, we use the 'alpha_is_used' bit from the VP8L bitstream to determine
the
same.
Detecting an absence of alpha can sometimes lead to much more efficient
rendering, especially for animated images.
Related: refine mux code to read width/height/has_alpha information only
once
per frame/fragment. This avoid frequent calls to VP8(L)GetInfo().
Change-Id: I4e0eef4db7d94425396c7dff6ca5599d5bca8297
Speed up HashChainFindCopy by optimizing on number of calls to
FindMatchLength method.
This change speeds up the lossless & lossy (Alpha) encoding by 20%
without loss of compression density.
At method=3, lossy (Alpha) compression speed (and density) remains
unchanged, as at that settings, the costly Backward Refs method is not
called
Change-Id: Ia1797148e9e4ee2787011837fa248afbae2242cb
Disable costly 'BackwardReferencesTraceBackwards' for encoding Alpha plane.
Increase the threshold for triggering 'BackwardReferencesTraceBackwards' to
quality 25 and above. Also lower the Alpha quality (at method 3) to be
lesser than this threshold (25).
Change-Id: Ic29fb2e6943472c564223df9fe099b19ccda0f31
This speeds up WebP lossless decoding by 20%. In particular, the
photographic images get 35% speedup.
Change-Id: Idb94750342a140ec05df52c07e12be4bba335adc
speeds up those codes that are not part of the main lookup.
This gives a 10 % speedup for a photographic image.
Change-Id: Ief54b0ad77db790a01314402ad351b40ac9a7be4
This is to ensure that the output WebP image is consistent with original
GIF when displayed against any background color.
Change-Id: I14218848153eb40358aa4ce331b2543d2fc2e86c
+ some revamp and cleanup of the alpha-filter trial loop
+ EncodeAlphaInternal() now just takes a FilterTrial param
Change-Id: Ief84385083b1cba02678bbcd3dbf707245ee962f
Specialize and simplify the alpha-decoding case, which is used when:
- no color-cache is use
- all red/blue/alpha values are the same (and hence their Huffman tree has
only 1 symbol. We don't need to consume any bits for reading these).
+ revamped the loop to use size_t and offsets instead of pointers.
~2-3% faster on Unix (gcc) but up to 25% faster lossy+alpha decoding
on Mac (llvm) and ARM.
Change-Id: I43c9688d1e4811cab0ecf0108a5b8f45781083e6
