diff options
Diffstat (limited to 'src/enc/histogram.c')
| -rw-r--r-- | src/enc/histogram.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/src/enc/histogram.c b/src/enc/histogram.c index ca838e06..c5b84bf7 100644 --- a/src/enc/histogram.c +++ b/src/enc/histogram.c @@ -55,9 +55,9 @@ VP8LHistogramSet* VP8LAllocateHistogramSet(int size, int cache_bits) { int i; VP8LHistogramSet* set; VP8LHistogram* bulk; - const uint64_t total_size = (uint64_t)sizeof(*set) - + size * sizeof(*set->histograms) - + size * sizeof(**set->histograms); + const uint64_t total_size = sizeof(*set) + + (uint64_t)size * sizeof(*set->histograms) + + (uint64_t)size * sizeof(**set->histograms); uint8_t* memory = (uint8_t*)WebPSafeMalloc(total_size, sizeof(*memory)); if (memory == NULL) return NULL; @@ -249,14 +249,15 @@ static uint32_t MyRand(uint32_t *seed) { } static int HistogramCombine(const VP8LHistogramSet* const in, - VP8LHistogramSet* const out, int num_pairs) { + VP8LHistogramSet* const out, int iter_mult, + int num_pairs, int num_tries_no_success) { int ok = 0; int i, iter; uint32_t seed = 0; int tries_with_no_success = 0; - const int min_cluster_size = 2; int out_size = in->size; - const int outer_iters = in->size * 3; + const int outer_iters = in->size * iter_mult; + const int min_cluster_size = 2; VP8LHistogram* const histos = (VP8LHistogram*)malloc(2 * sizeof(*histos)); VP8LHistogram* cur_combo = histos + 0; // trial merged histogram VP8LHistogram* best_combo = histos + 1; // best merged histogram so far @@ -271,12 +272,12 @@ static int HistogramCombine(const VP8LHistogramSet* const in, // Collapse similar histograms in 'out'. for (iter = 0; iter < outer_iters && out_size >= min_cluster_size; ++iter) { - // We pick the best pair to be combined out of 'inner_iters' pairs. double best_cost_diff = 0.; int best_idx1 = 0, best_idx2 = 1; int j; + const int num_tries = (num_pairs < out_size) ? num_pairs : out_size; seed += iter; - for (j = 0; j < num_pairs; ++j) { + for (j = 0; j < num_tries; ++j) { double curr_cost_diff; // Choose two histograms at random and try to combine them. const uint32_t idx1 = MyRand(&seed) % out_size; @@ -315,7 +316,7 @@ static int HistogramCombine(const VP8LHistogramSet* const in, } tries_with_no_success = 0; } - if (++tries_with_no_success >= 50) { + if (++tries_with_no_success >= num_tries_no_success) { break; } } @@ -384,16 +385,27 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize, int ok = 0; const int histo_xsize = histo_bits ? VP8LSubSampleSize(xsize, histo_bits) : 1; const int histo_ysize = histo_bits ? VP8LSubSampleSize(ysize, histo_bits) : 1; - const int num_histo_pairs = 10 + quality / 2; // For HistogramCombine(). const int histo_image_raw_size = histo_xsize * histo_ysize; + + // Heuristic params for HistogramCombine(). + const int num_tries_no_success = 8 + (quality >> 1); + const int iter_mult = (quality < 27) ? 1 : 1 + ((quality - 27) >> 4); + int num_pairs = (quality >> 1); + VP8LHistogramSet* const image_out = VP8LAllocateHistogramSet(histo_image_raw_size, cache_bits); if (image_out == NULL) return 0; + if (num_pairs > (histo_image_raw_size >> 2)) { + num_pairs = histo_image_raw_size >> 2; + } + num_pairs += 10; + // Build histogram image. HistogramBuildImage(xsize, histo_bits, refs, image_out); // Collapse similar histograms. - if (!HistogramCombine(image_out, image_in, num_histo_pairs)) { + if (!HistogramCombine(image_out, image_in, iter_mult, num_pairs, + num_tries_no_success)) { goto Error; } // Find the optimal map from original histograms to the final ones. |