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Apply the RLE heuristic to LZ77.

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Change-Id: I7317eed7e017ee8981f40fcf1737f97e0e3a238c
This commit is contained in:
Vincent Rabaud 2016-07-14 19:21:07 +02:00
parent fe57273736
commit 2a5c417c68
3 changed files with 38 additions and 17 deletions
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21
src/enc/backward_references.c
View File

@ -242,7 +242,8 @@ static WEBP_INLINE int MaxFindCopyLength(int len) {
}
int VP8LHashChainFill(VP8LHashChain* const p, int quality,
const uint32_t* const argb, int xsize, int ysize) {
const uint32_t* const argb, int xsize, int ysize,
int low_effort) {
const int size = xsize * ysize;
const int iter_max = GetMaxItersForQuality(quality);
const int iter_min = iter_max - quality / 10;
@ -285,7 +286,23 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
const int length_max = (max_len < 256) ? max_len : 256;
uint32_t max_base_position;
for (pos = chain[base_position]; pos >= min_pos; pos = chain[pos]) {
pos = chain[base_position];
if (!low_effort) {
// Heuristic: use the comparison with the above line as an initialization.
if (base_position >= (uint32_t)xsize) {
const int curr_length = FindMatchLength(argb_start - xsize, argb_start,
best_length, max_len);
if (curr_length > best_length) {
best_length = curr_length;
best_distance = xsize;
}
}
--iter;
// Skip the for loop if we already have the maximum.
if (best_length == MAX_LENGTH) pos = min_pos - 1;
}
for (; pos >= min_pos; pos = chain[pos]) {
int curr_length;
if (--iter < 0) {
break;

3
src/enc/backward_references.h
View File

@ -130,7 +130,8 @@ struct VP8LHashChain {
int VP8LHashChainInit(VP8LHashChain* const p, int size);
// Pre-compute the best matches for argb.
int VP8LHashChainFill(VP8LHashChain* const p, int quality,
const uint32_t* const argb, int xsize, int ysize);
const uint32_t* const argb, int xsize, int ysize,
int low_effort);
void VP8LHashChainClear(VP8LHashChain* const p); // release memory
// -----------------------------------------------------------------------------

31
src/enc/vp8l.c
View File

@ -697,7 +697,7 @@ static WebPEncodingError EncodeImageNoHuffman(VP8LBitWriter* const bw,
VP8LHashChain* const hash_chain,
VP8LBackwardRefs refs_array[2],
int width, int height,
int quality) {
int quality, int low_effort) {
int i;
int max_tokens = 0;
WebPEncodingError err = VP8_ENC_OK;
@ -715,7 +715,8 @@ static WebPEncodingError EncodeImageNoHuffman(VP8LBitWriter* const bw,
}
// Calculate backward references from ARGB image.
if (VP8LHashChainFill(hash_chain, quality, argb, width, height) == 0) {
if (!VP8LHashChainFill(hash_chain, quality, argb, width, height,
low_effort)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
@ -819,7 +820,8 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
// 'best_refs' is the reference to the best backward refs and points to one
// of refs_array[0] or refs_array[1].
// Calculate backward references from ARGB image.
if (VP8LHashChainFill(hash_chain, quality, argb, width, height) == 0) {
if (!VP8LHashChainFill(hash_chain, quality, argb, width, height,
low_effort)) {
err = VP8_ENC_ERROR_OUT_OF_MEMORY;
goto Error;
}
@ -900,7 +902,7 @@ static WebPEncodingError EncodeImageInternal(VP8LBitWriter* const bw,
err = EncodeImageNoHuffman(bw, histogram_argb, hash_chain, refs_array,
VP8LSubSampleSize(width, histogram_bits),
VP8LSubSampleSize(height, histogram_bits),
quality);
quality, low_effort);
WebPSafeFree(histogram_argb);
if (err != VP8_ENC_OK) goto Error;
}
@ -991,12 +993,12 @@ static WebPEncodingError ApplyPredictFilter(const VP8LEncoder* const enc,
(VP8LHashChain*)&enc->hash_chain_,
(VP8LBackwardRefs*)enc->refs_, // cast const away
transform_width, transform_height,
quality);
quality, low_effort);
}
static WebPEncodingError ApplyCrossColorFilter(const VP8LEncoder* const enc,
int width, int height,
int quality,
int quality, int low_effort,
VP8LBitWriter* const bw) {
const int ccolor_transform_bits = enc->transform_bits_;
const int transform_width = VP8LSubSampleSize(width, ccolor_transform_bits);
@ -1012,7 +1014,7 @@ static WebPEncodingError ApplyCrossColorFilter(const VP8LEncoder* const enc,
(VP8LHashChain*)&enc->hash_chain_,
(VP8LBackwardRefs*)enc->refs_, // cast const away
transform_width, transform_height,
quality);
quality, low_effort);
}
// -----------------------------------------------------------------------------
@ -1291,7 +1293,7 @@ static WebPEncodingError MapImageFromPalette(VP8LEncoder* const enc,
}
// Save palette_[] to bitstream.
static WebPEncodingError EncodePalette(VP8LBitWriter* const bw,
static WebPEncodingError EncodePalette(VP8LBitWriter* const bw, int low_effort,
VP8LEncoder* const enc) {
int i;
uint32_t tmp_palette[MAX_PALETTE_SIZE];
@ -1306,13 +1308,14 @@ static WebPEncodingError EncodePalette(VP8LBitWriter* const bw,
}
tmp_palette[0] = palette[0];
return EncodeImageNoHuffman(bw, tmp_palette, &enc->hash_chain_, enc->refs_,
palette_size, 1, 20 /* quality */);
palette_size, 1, 20 /* quality */, low_effort);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
static WebPEncodingError EncodeDeltaPalettePredictorImage(
VP8LBitWriter* const bw, VP8LEncoder* const enc, int quality) {
VP8LBitWriter* const bw, VP8LEncoder* const enc, int quality,
int low_effort) {
const WebPPicture* const pic = enc->pic_;
const int width = pic->width;
const int height = pic->height;
@ -1343,7 +1346,7 @@ static WebPEncodingError EncodeDeltaPalettePredictorImage(
err = EncodeImageNoHuffman(bw, predictors, &enc->hash_chain_,
(VP8LBackwardRefs*)enc->refs_, // cast const away
transform_width, transform_height,
quality);
quality, low_effort);
WebPSafeFree(predictors);
return err;
}
@ -1433,7 +1436,7 @@ WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
if (enc->use_palette_) {
err = AllocateTransformBuffer(enc, width, height);
if (err != VP8_ENC_OK) goto Error;
err = EncodeDeltaPalettePredictorImage(bw, enc, quality);
err = EncodeDeltaPalettePredictorImage(bw, enc, quality, low_effort);
if (err != VP8_ENC_OK) goto Error;
use_delta_palettization = 1;
}
@ -1442,7 +1445,7 @@ WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
// Encode palette
if (enc->use_palette_) {
err = EncodePalette(bw, enc);
err = EncodePalette(bw, low_effort, enc);
if (err != VP8_ENC_OK) goto Error;
err = MapImageFromPalette(enc, use_delta_palettization);
if (err != VP8_ENC_OK) goto Error;
@ -1469,7 +1472,7 @@ WebPEncodingError VP8LEncodeStream(const WebPConfig* const config,
if (enc->use_cross_color_) {
err = ApplyCrossColorFilter(enc, enc->current_width_,
height, quality, bw);
height, quality, low_effort, bw);
if (err != VP8_ENC_OK) goto Error;
}
}