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Cosmetic changes in backward reference.

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Change-Id: Ieb3dd65a647c034f67cf029e7b03f843b4650b0f
This commit is contained in:
Vincent Rabaud 2017-05-29 16:00:44 +02:00
parent e4eb458741
commit 498cad34be
1 changed files with 54 additions and 74 deletions
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130
src/enc/backward_references_enc.c
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@ -629,7 +629,7 @@ static WEBP_INLINE void AddSingleLiteralWithCostModel(
const CostModel* const cost_model, int idx, int use_color_cache,
float prev_cost, float* const cost, uint16_t* const dist_array) {
double cost_val = prev_cost;
const uint32_t color = argb[0];
const uint32_t color = argb[idx];
const int ix = use_color_cache ? VP8LColorCacheContains(hashers, color) : -1;
if (ix >= 0) {
// use_color_cache is true and hashers contains color
@ -772,7 +772,7 @@ static int CostManagerInit(CostManager* const manager,
manager->cost_cache_[0] = GetLengthCost(cost_model, 0);
for (i = 1; i < cost_cache_size; ++i) {
manager->cost_cache_[i] = GetLengthCost(cost_model, i);
// Get an approximation of the number of bound intervals.
// Get the number of bound intervals.
if (manager->cost_cache_[i] != manager->cost_cache_[i - 1]) {
++manager->cache_intervals_size_;
}
@ -809,7 +809,6 @@ static int CostManagerInit(CostManager* const manager,
}
cur->end_ = i + 1;
}
manager->cache_intervals_size_ = cur + 1 - manager->cache_intervals_;
}
manager->costs_ = (float*)WebPSafeMalloc(pix_count, sizeof(*manager->costs_));
@ -1110,9 +1109,8 @@ static int BackwardReferencesHashChainDistanceOnly(
// non-processed locations from this point.
dist_array[0] = 0;
// Add first pixel as literal.
AddSingleLiteralWithCostModel(argb + 0, &hashers, cost_model, 0,
use_color_cache, 0.f, cost_manager->costs_,
dist_array);
AddSingleLiteralWithCostModel(argb, &hashers, cost_model, 0, use_color_cache,
0.f, cost_manager->costs_, dist_array);
for (i = 1; i < pix_count; ++i) {
const float prev_cost = cost_manager->costs_[i - 1];
@ -1120,7 +1118,7 @@ static int BackwardReferencesHashChainDistanceOnly(
HashChainFindCopy(hash_chain, i, &offset, &len);
// Try adding the pixel as a literal.
AddSingleLiteralWithCostModel(argb + i, &hashers, cost_model, i,
AddSingleLiteralWithCostModel(argb, &hashers, cost_model, i,
use_color_cache, prev_cost,
cost_manager->costs_, dist_array);
@ -1457,79 +1455,61 @@ static VP8LBackwardRefs* GetBackwardReferencesLowEffort(
static VP8LBackwardRefs* GetBackwardReferences(
int width, int height, const uint32_t* const argb, int quality,
int* const cache_bits, const VP8LHashChain* const hash_chain,
VP8LBackwardRefs* const refs_lz77, VP8LBackwardRefs* const refs_rle) {
int lz77_is_useful;
int cache_bits_lz77 = *cache_bits, cache_bits_rle = *cache_bits;
double bit_cost_lz77, bit_cost_rle;
VP8LBackwardRefs* best = NULL;
VP8LBackwardRefs* best, VP8LBackwardRefs* worst) {
const int cache_bits_initial = *cache_bits;
double bit_cost_best = -1;
VP8LHistogram* histo = NULL;
int i, i_best = 0;
// Compute LZ77 with no cache (0 bits), as the ideal LZ77 with a color cache
// is not that different in practice.
if (!BackwardReferencesLz77(width, height, argb, 0, hash_chain, refs_lz77)) {
goto Error;
}
if (!CalculateBestCacheSize(argb, quality, refs_lz77, &cache_bits_lz77)) {
goto Error;
}
// Transform refs_lz77 for the optimized cache_bits_lz77.
if (cache_bits_lz77 > 0) {
if (!BackwardRefsWithLocalCache(argb, cache_bits_lz77, refs_lz77)) {
goto Error;
}
}
// RLE.
if (!BackwardReferencesRle(width, height, argb, 0, refs_rle)) {
goto Error;
}
if (!CalculateBestCacheSize(argb, quality, refs_rle, &cache_bits_rle)) {
goto Error;
}
// Transform refs_rle for the optimized cache_bits_rle.
if (cache_bits_rle > 0) {
if (!BackwardRefsWithLocalCache(argb, cache_bits_rle, refs_rle)) {
goto Error;
}
}
{
// Evaluate RLE coding.
histo = VP8LAllocateHistogram(cache_bits_rle);
histo = VP8LAllocateHistogram(MAX_COLOR_CACHE_BITS);
if (histo == NULL) goto Error;
VP8LHistogramCreate(histo, refs_rle, cache_bits_rle);
bit_cost_rle = VP8LHistogramEstimateBits(histo);
VP8LFreeHistogram(histo);
// Evaluate LZ77 coding.
histo = VP8LAllocateHistogram(cache_bits_lz77);
if (histo == NULL) goto Error;
VP8LHistogramCreate(histo, refs_lz77, cache_bits_lz77);
bit_cost_lz77 = VP8LHistogramEstimateBits(histo);
// Decide if LZ77 is useful.
lz77_is_useful = (bit_cost_lz77 < bit_cost_rle);
}
// Choose appropriate backward reference.
if (lz77_is_useful) {
// TraceBackwards is costly. Don't execute it at lower quality.
const int try_lz77_trace_backwards = (quality >= 25);
best = refs_lz77; // default guess: lz77 is better
if (try_lz77_trace_backwards) {
if (BackwardReferencesTraceBackwards(width, height, argb, cache_bits_lz77,
hash_chain, refs_lz77, refs_rle)) {
double bit_cost_trace;
// Evaluate LZ77 coding.
VP8LHistogramCreate(histo, refs_rle, cache_bits_lz77);
bit_cost_trace = VP8LHistogramEstimateBits(histo);
if (bit_cost_trace < bit_cost_lz77) {
best = refs_rle;
}
}
}
*cache_bits = cache_bits_lz77;
// Try out RLE first, then LZ77.
for (i = 0; i <= 1; ++i) {
int res;
double bit_cost;
int cache_bits_tmp = cache_bits_initial;
// First, try out backward references with no cache (0 bits).
if (i == 0) {
res = BackwardReferencesRle(width, height, argb, 0, worst);
} else {
best = refs_rle;
*cache_bits = cache_bits_rle;
res = BackwardReferencesLz77(width, height, argb, 0, hash_chain, worst);
}
if (!res) goto Error;
// Next, try with a color cache and update the references.
if (!CalculateBestCacheSize(argb, quality, worst, &cache_bits_tmp)) {
goto Error;
}
if (cache_bits_tmp > 0) {
if (!BackwardRefsWithLocalCache(argb, cache_bits_tmp, worst)) {
goto Error;
}
}
// Keep the best backward references.
VP8LHistogramCreate(histo, worst, cache_bits_tmp);
bit_cost = VP8LHistogramEstimateBits(histo);
if (i == 0 || bit_cost < bit_cost_best) {
VP8LBackwardRefs* const tmp = worst;
worst = best;
best = tmp;
bit_cost_best = bit_cost;
*cache_bits = cache_bits_tmp;
i_best = i;
}
}
// Improve on simple LZ77 but only for high quality (TraceBackwards is
// costly).
if (i_best == 1 && quality >= 25) {
if (BackwardReferencesTraceBackwards(width, height, argb, *cache_bits,
hash_chain, best, worst)) {
double bit_cost_trace;
VP8LHistogramCreate(histo, worst, *cache_bits);
bit_cost_trace = VP8LHistogramEstimateBits(histo);
if (bit_cost_trace < bit_cost_best) best = worst;
}
}
BackwardReferences2DLocality(width, best);