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Improve speed and compression in backward reference for lossless.

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Change-Id: I664c5e68b036a2d424192962dbad873a2c70b826
This commit is contained in:
Vincent Rabaud
2016-06-08 19:19:08 +02:00
parent 0481d42ad8
commit 0ba7fd70c6
3 changed files with 162 additions and 140 deletions
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11
src/enc/backward_references.h
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@ -115,9 +115,12 @@ static WEBP_INLINE uint32_t PixOrCopyDistance(const PixOrCopy* const p) {
typedef struct VP8LHashChain VP8LHashChain;
struct VP8LHashChain {
// chain_[pos] stores the previous position with the same hash value
// for every pixel in the image.
int32_t* chain_;
// The 20 most significant bits contain the offset at which the best match
// is found. These 20 bits are the limit defined by GetWindowSizeForHashChain
// (through WINDOW_SIZE = 1<<20).
// The lower 12 bits contain the length of the match. The 12 bit limit is
// defined in MaxFindCopyLength with MAX_LENGTH=4096.
uint32_t* offset_length_;
// This is the maximum size of the hash_chain that can be constructed.
// Typically this is the pixel count (width x height) for a given image.
int size_;
@ -126,7 +129,7 @@ struct VP8LHashChain {
// Must be called first, to set size.
int VP8LHashChainInit(VP8LHashChain* const p, int size);
// Pre-compute the best matches for argb.
int VP8LHashChainFill(VP8LHashChain* const p,
int VP8LHashChainFill(VP8LHashChain* const p, int quality,
const uint32_t* const argb, int xsize, int ysize);
void VP8LHashChainClear(VP8LHashChain* const p); // release memory