Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2197 insertions, 0 deletions

diff --git a/media/libwebp/src/enc/vp8l_enc.c b/media/libwebp/src/enc/vp8l_enc.c
new file mode 100644
index 0000000000..2b345df610
--- /dev/null
+++ b/media/libwebp/src/enc/vp8l_enc.c
@@ -0,0 +1,2197 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// main entry for the lossless encoder.
+//
+// Author: Vikas Arora (vikaas.arora@gmail.com)
+//
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "src/dsp/lossless.h"
+#include "src/dsp/lossless_common.h"
+#include "src/enc/backward_references_enc.h"
+#include "src/enc/histogram_enc.h"
+#include "src/enc/vp8i_enc.h"
+#include "src/enc/vp8li_enc.h"
+#include "src/utils/bit_writer_utils.h"
+#include "src/utils/huffman_encode_utils.h"
+#include "src/utils/utils.h"
+#include "src/webp/encode.h"
+#include "src/webp/format_constants.h"
+
+// Maximum number of histogram images (sub-blocks).
+#define MAX_HUFF_IMAGE_SIZE       2600
+
+// Palette reordering for smaller sum of deltas (and for smaller storage).
+
+static int PaletteCompareColorsForQsort(const void* p1, const void* p2) {
+  const uint32_t a = WebPMemToUint32((uint8_t*)p1);
+  const uint32_t b = WebPMemToUint32((uint8_t*)p2);
+  assert(a != b);
+  return (a < b) ? -1 : 1;
+}
+
+static WEBP_INLINE uint32_t PaletteComponentDistance(uint32_t v) {
+  return (v <= 128) ? v : (256 - v);
+}
+
+// Computes a value that is related to the entropy created by the
+// palette entry diff.
+//
+// Note that the last & 0xff is a no-operation in the next statement, but
+// removed by most compilers and is here only for regularity of the code.
+static WEBP_INLINE uint32_t PaletteColorDistance(uint32_t col1, uint32_t col2) {
+  const uint32_t diff = VP8LSubPixels(col1, col2);
+  const int kMoreWeightForRGBThanForAlpha = 9;
+  uint32_t score;
+  score =  PaletteComponentDistance((diff >>  0) & 0xff);
+  score += PaletteComponentDistance((diff >>  8) & 0xff);
+  score += PaletteComponentDistance((diff >> 16) & 0xff);
+  score *= kMoreWeightForRGBThanForAlpha;
+  score += PaletteComponentDistance((diff >> 24) & 0xff);
+  return score;
+}
+
+static WEBP_INLINE void SwapColor(uint32_t* const col1, uint32_t* const col2) {
+  const uint32_t tmp = *col1;
+  *col1 = *col2;
+  *col2 = tmp;
+}
+
+static WEBP_INLINE int SearchColorNoIdx(const uint32_t sorted[], uint32_t color,
+                                        int num_colors) {
+  int low = 0, hi = num_colors;
+  if (sorted[low] == color) return low;  // loop invariant: sorted[low] != color
+  while (1) {
+    const int mid = (low + hi) >> 1;
+    if (sorted[mid] == color) {
+      return mid;
+    } else if (sorted[mid] < color) {
+      low = mid;
+    } else {
+      hi = mid;
+    }
+  }
+  assert(0);
+  return 0;
+}
+
+// The palette has been sorted by alpha. This function checks if the other
+// components of the palette have a monotonic development with regards to
+// position in the palette. If all have monotonic development, there is
+// no benefit to re-organize them greedily. A monotonic development
+// would be spotted in green-only situations (like lossy alpha) or gray-scale
+// images.
+static int PaletteHasNonMonotonousDeltas(const uint32_t* const palette,
+                                         int num_colors) {
+  uint32_t predict = 0x000000;
+  int i;
+  uint8_t sign_found = 0x00;
+  for (i = 0; i < num_colors; ++i) {
+    const uint32_t diff = VP8LSubPixels(palette[i], predict);
+    const uint8_t rd = (diff >> 16) & 0xff;
+    const uint8_t gd = (diff >>  8) & 0xff;
+    const uint8_t bd = (diff >>  0) & 0xff;
+    if (rd != 0x00) {
+      sign_found |= (rd < 0x80) ? 1 : 2;
+    }
+    if (gd != 0x00) {
+      sign_found |= (gd < 0x80) ? 8 : 16;
+    }
+    if (bd != 0x00) {
+      sign_found |= (bd < 0x80) ? 64 : 128;
+    }
+    predict = palette[i];
+  }
+  return (sign_found & (sign_found << 1)) != 0;  // two consequent signs.
+}
+
+static void PaletteSortMinimizeDeltas(const uint32_t* const palette_sorted,
+                                      int num_colors, uint32_t* const palette) {
+  uint32_t predict = 0x00000000;
+  int i, k;
+  memcpy(palette, palette_sorted, num_colors * sizeof(*palette));
+  if (!PaletteHasNonMonotonousDeltas(palette_sorted, num_colors)) return;
+  // Find greedily always the closest color of the predicted color to minimize
+  // deltas in the palette. This reduces storage needs since the
+  // palette is stored with delta encoding.
+  for (i = 0; i < num_colors; ++i) {
+    int best_ix = i;
+    uint32_t best_score = ~0U;
+    for (k = i; k < num_colors; ++k) {
+      const uint32_t cur_score = PaletteColorDistance(palette[k], predict);
+      if (best_score > cur_score) {
+        best_score = cur_score;
+        best_ix = k;
+      }
+    }
+    SwapColor(&palette[best_ix], &palette[i]);
+    predict = palette[i];
+  }
+}
+
+// Sort palette in increasing order and prepare an inverse mapping array.
+static void PrepareMapToPalette(const uint32_t palette[], uint32_t num_colors,
+                                uint32_t sorted[], uint32_t idx_map[]) {
+  uint32_t i;
+  memcpy(sorted, palette, num_colors * sizeof(*sorted));
+  qsort(sorted, num_colors, sizeof(*sorted), PaletteCompareColorsForQsort);
+  for (i = 0; i < num_colors; ++i) {
+    idx_map[SearchColorNoIdx(sorted, palette[i], num_colors)] = i;
+  }
+}
+
+// -----------------------------------------------------------------------------
+// Modified Zeng method from "A Survey on Palette Reordering
+// Methods for Improving the Compression of Color-Indexed Images" by Armando J.
+// Pinho and Antonio J. R. Neves.
+
+// Finds the biggest cooccurrence in the matrix.
+static void CoOccurrenceFindMax(const uint32_t* const cooccurrence,
+                                uint32_t num_colors, uint8_t* const c1,
+                                uint8_t* const c2) {
+  // Find the index that is most frequently located adjacent to other
+  // (different) indexes.
+  uint32_t best_sum = 0u;
+  uint32_t i, j, best_cooccurrence;
+  *c1 = 0u;
+  for (i = 0; i < num_colors; ++i) {
+    uint32_t sum = 0;
+    for (j = 0; j < num_colors; ++j) sum += cooccurrence[i * num_colors + j];
+    if (sum > best_sum) {
+      best_sum = sum;
+      *c1 = i;
+    }
+  }
+  // Find the index that is most frequently found adjacent to *c1.
+  *c2 = 0u;
+  best_cooccurrence = 0u;
+  for (i = 0; i < num_colors; ++i) {
+    if (cooccurrence[*c1 * num_colors + i] > best_cooccurrence) {
+      best_cooccurrence = cooccurrence[*c1 * num_colors + i];
+      *c2 = i;
+    }
+  }
+  assert(*c1 != *c2);
+}
+
+// Builds the cooccurrence matrix
+static int CoOccurrenceBuild(const WebPPicture* const pic,
+                             const uint32_t* const palette, uint32_t num_colors,
+                             uint32_t* cooccurrence) {
+  uint32_t *lines, *line_top, *line_current, *line_tmp;
+  int x, y;
+  const uint32_t* src = pic->argb;
+  uint32_t prev_pix = ~src[0];
+  uint32_t prev_idx = 0u;
+  uint32_t idx_map[MAX_PALETTE_SIZE] = {0};
+  uint32_t palette_sorted[MAX_PALETTE_SIZE];
+  lines = (uint32_t*)WebPSafeMalloc(2 * pic->width, sizeof(*lines));
+  if (lines == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    return 0;
+  }
+  line_top = &lines[0];
+  line_current = &lines[pic->width];
+  PrepareMapToPalette(palette, num_colors, palette_sorted, idx_map);
+  for (y = 0; y < pic->height; ++y) {
+    for (x = 0; x < pic->width; ++x) {
+      const uint32_t pix = src[x];
+      if (pix != prev_pix) {
+        prev_idx = idx_map[SearchColorNoIdx(palette_sorted, pix, num_colors)];
+        prev_pix = pix;
+      }
+      line_current[x] = prev_idx;
+      // 4-connectivity is what works best as mentioned in "On the relation
+      // between Memon's and the modified Zeng's palette reordering methods".
+      if (x > 0 && prev_idx != line_current[x - 1]) {
+        const uint32_t left_idx = line_current[x - 1];
+        ++cooccurrence[prev_idx * num_colors + left_idx];
+        ++cooccurrence[left_idx * num_colors + prev_idx];
+      }
+      if (y > 0 && prev_idx != line_top[x]) {
+        const uint32_t top_idx = line_top[x];
+        ++cooccurrence[prev_idx * num_colors + top_idx];
+        ++cooccurrence[top_idx * num_colors + prev_idx];
+      }
+    }
+    line_tmp = line_top;
+    line_top = line_current;
+    line_current = line_tmp;
+    src += pic->argb_stride;
+  }
+  WebPSafeFree(lines);
+  return 1;
+}
+
+struct Sum {
+  uint8_t index;
+  uint32_t sum;
+};
+
+// Implements the modified Zeng method from "A Survey on Palette Reordering
+// Methods for Improving the Compression of Color-Indexed Images" by Armando J.
+// Pinho and Antonio J. R. Neves.
+static int PaletteSortModifiedZeng(
+    const WebPPicture* const pic, const uint32_t* const palette_sorted,
+    uint32_t num_colors, uint32_t* const palette) {
+  uint32_t i, j, ind;
+  uint8_t remapping[MAX_PALETTE_SIZE];
+  uint32_t* cooccurrence;
+  struct Sum sums[MAX_PALETTE_SIZE];
+  uint32_t first, last;
+  uint32_t num_sums;
+  // TODO(vrabaud) check whether one color images should use palette or not.
+  if (num_colors <= 1) return 1;
+  // Build the co-occurrence matrix.
+  cooccurrence =
+      (uint32_t*)WebPSafeCalloc(num_colors * num_colors, sizeof(*cooccurrence));
+  if (cooccurrence == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    return 0;
+  }
+  if (!CoOccurrenceBuild(pic, palette_sorted, num_colors, cooccurrence)) {
+    return 0;
+  }
+
+  // Initialize the mapping list with the two best indices.
+  CoOccurrenceFindMax(cooccurrence, num_colors, &remapping[0], &remapping[1]);
+
+  // We need to append and prepend to the list of remapping. To this end, we
+  // actually define the next start/end of the list as indices in a vector (with
+  // a wrap around when the end is reached).
+  first = 0;
+  last = 1;
+  num_sums = num_colors - 2;  // -2 because we know the first two values
+  if (num_sums > 0) {
+    // Initialize the sums with the first two remappings and find the best one
+    struct Sum* best_sum = &sums[0];
+    best_sum->index = 0u;
+    best_sum->sum = 0u;
+    for (i = 0, j = 0; i < num_colors; ++i) {
+      if (i == remapping[0] || i == remapping[1]) continue;
+      sums[j].index = i;
+      sums[j].sum = cooccurrence[i * num_colors + remapping[0]] +
+                    cooccurrence[i * num_colors + remapping[1]];
+      if (sums[j].sum > best_sum->sum) best_sum = &sums[j];
+      ++j;
+    }
+
+    while (num_sums > 0) {
+      const uint8_t best_index = best_sum->index;
+      // Compute delta to know if we need to prepend or append the best index.
+      int32_t delta = 0;
+      const int32_t n = num_colors - num_sums;
+      for (ind = first, j = 0; (ind + j) % num_colors != last + 1; ++j) {
+        const uint16_t l_j = remapping[(ind + j) % num_colors];
+        delta += (n - 1 - 2 * (int32_t)j) *
+                 (int32_t)cooccurrence[best_index * num_colors + l_j];
+      }
+      if (delta > 0) {
+        first = (first == 0) ? num_colors - 1 : first - 1;
+        remapping[first] = best_index;
+      } else {
+        ++last;
+        remapping[last] = best_index;
+      }
+      // Remove best_sum from sums.
+      *best_sum = sums[num_sums - 1];
+      --num_sums;
+      // Update all the sums and find the best one.
+      best_sum = &sums[0];
+      for (i = 0; i < num_sums; ++i) {
+        sums[i].sum += cooccurrence[best_index * num_colors + sums[i].index];
+        if (sums[i].sum > best_sum->sum) best_sum = &sums[i];
+      }
+    }
+  }
+  assert((last + 1) % num_colors == first);
+  WebPSafeFree(cooccurrence);
+
+  // Re-map the palette.
+  for (i = 0; i < num_colors; ++i) {
+    palette[i] = palette_sorted[remapping[(first + i) % num_colors]];
+  }
+  return 1;
+}
+
+// -----------------------------------------------------------------------------
+// Palette
+
+// These five modes are evaluated and their respective entropy is computed.
+typedef enum {
+  kDirect = 0,
+  kSpatial = 1,
+  kSubGreen = 2,
+  kSpatialSubGreen = 3,
+  kPalette = 4,
+  kPaletteAndSpatial = 5,
+  kNumEntropyIx = 6
+} EntropyIx;
+
+typedef enum {
+  kSortedDefault = 0,
+  kMinimizeDelta = 1,
+  kModifiedZeng = 2,
+  kUnusedPalette = 3,
+} PaletteSorting;
+
+typedef enum {
+  kHistoAlpha = 0,
+  kHistoAlphaPred,
+  kHistoGreen,
+  kHistoGreenPred,
+  kHistoRed,
+  kHistoRedPred,
+  kHistoBlue,
+  kHistoBluePred,
+  kHistoRedSubGreen,
+  kHistoRedPredSubGreen,
+  kHistoBlueSubGreen,
+  kHistoBluePredSubGreen,
+  kHistoPalette,
+  kHistoTotal  // Must be last.
+} HistoIx;
+
+static void AddSingleSubGreen(int p, uint32_t* const r, uint32_t* const b) {
+  const int green = p >> 8;  // The upper bits are masked away later.
+  ++r[((p >> 16) - green) & 0xff];
+  ++b[((p >>  0) - green) & 0xff];
+}
+
+static void AddSingle(uint32_t p,
+                      uint32_t* const a, uint32_t* const r,
+                      uint32_t* const g, uint32_t* const b) {
+  ++a[(p >> 24) & 0xff];
+  ++r[(p >> 16) & 0xff];
+  ++g[(p >>  8) & 0xff];
+  ++b[(p >>  0) & 0xff];
+}
+
+static WEBP_INLINE uint32_t HashPix(uint32_t pix) {
+  // Note that masking with 0xffffffffu is for preventing an
+  // 'unsigned int overflow' warning. Doesn't impact the compiled code.
+  return ((((uint64_t)pix + (pix >> 19)) * 0x39c5fba7ull) & 0xffffffffu) >> 24;
+}
+
+static int AnalyzeEntropy(const uint32_t* argb,
+                          int width, int height, int argb_stride,
+                          int use_palette,
+                          int palette_size, int transform_bits,
+                          EntropyIx* const min_entropy_ix,
+                          int* const red_and_blue_always_zero) {
+  // Allocate histogram set with cache_bits = 0.
+  uint32_t* histo;
+
+  if (use_palette && palette_size <= 16) {
+    // In the case of small palettes, we pack 2, 4 or 8 pixels together. In
+    // practice, small palettes are better than any other transform.
+    *min_entropy_ix = kPalette;
+    *red_and_blue_always_zero = 1;
+    return 1;
+  }
+  histo = (uint32_t*)WebPSafeCalloc(kHistoTotal, sizeof(*histo) * 256);
+  if (histo != NULL) {
+    int i, x, y;
+    const uint32_t* prev_row = NULL;
+    const uint32_t* curr_row = argb;
+    uint32_t pix_prev = argb[0];  // Skip the first pixel.
+    for (y = 0; y < height; ++y) {
+      for (x = 0; x < width; ++x) {
+        const uint32_t pix = curr_row[x];
+        const uint32_t pix_diff = VP8LSubPixels(pix, pix_prev);
+        pix_prev = pix;
+        if ((pix_diff == 0) || (prev_row != NULL && pix == prev_row[x])) {
+          continue;
+        }
+        AddSingle(pix,
+                  &histo[kHistoAlpha * 256],
+                  &histo[kHistoRed * 256],
+                  &histo[kHistoGreen * 256],
+                  &histo[kHistoBlue * 256]);
+        AddSingle(pix_diff,
+                  &histo[kHistoAlphaPred * 256],
+                  &histo[kHistoRedPred * 256],
+                  &histo[kHistoGreenPred * 256],
+                  &histo[kHistoBluePred * 256]);
+        AddSingleSubGreen(pix,
+                          &histo[kHistoRedSubGreen * 256],
+                          &histo[kHistoBlueSubGreen * 256]);
+        AddSingleSubGreen(pix_diff,
+                          &histo[kHistoRedPredSubGreen * 256],
+                          &histo[kHistoBluePredSubGreen * 256]);
+        {
+          // Approximate the palette by the entropy of the multiplicative hash.
+          const uint32_t hash = HashPix(pix);
+          ++histo[kHistoPalette * 256 + hash];
+        }
+      }
+      prev_row = curr_row;
+      curr_row += argb_stride;
+    }
+    {
+      float entropy_comp[kHistoTotal];
+      float entropy[kNumEntropyIx];
+      int k;
+      int last_mode_to_analyze = use_palette ? kPalette : kSpatialSubGreen;
+      int j;
+      // Let's add one zero to the predicted histograms. The zeros are removed
+      // too efficiently by the pix_diff == 0 comparison, at least one of the
+      // zeros is likely to exist.
+      ++histo[kHistoRedPredSubGreen * 256];
+      ++histo[kHistoBluePredSubGreen * 256];
+      ++histo[kHistoRedPred * 256];
+      ++histo[kHistoGreenPred * 256];
+      ++histo[kHistoBluePred * 256];
+      ++histo[kHistoAlphaPred * 256];
+
+      for (j = 0; j < kHistoTotal; ++j) {
+        entropy_comp[j] = VP8LBitsEntropy(&histo[j * 256], 256);
+      }
+      entropy[kDirect] = entropy_comp[kHistoAlpha] +
+          entropy_comp[kHistoRed] +
+          entropy_comp[kHistoGreen] +
+          entropy_comp[kHistoBlue];
+      entropy[kSpatial] = entropy_comp[kHistoAlphaPred] +
+          entropy_comp[kHistoRedPred] +
+          entropy_comp[kHistoGreenPred] +
+          entropy_comp[kHistoBluePred];
+      entropy[kSubGreen] = entropy_comp[kHistoAlpha] +
+          entropy_comp[kHistoRedSubGreen] +
+          entropy_comp[kHistoGreen] +
+          entropy_comp[kHistoBlueSubGreen];
+      entropy[kSpatialSubGreen] = entropy_comp[kHistoAlphaPred] +
+          entropy_comp[kHistoRedPredSubGreen] +
+          entropy_comp[kHistoGreenPred] +
+          entropy_comp[kHistoBluePredSubGreen];
+      entropy[kPalette] = entropy_comp[kHistoPalette];
+
+      // When including transforms, there is an overhead in bits from
+      // storing them. This overhead is small but matters for small images.
+      // For spatial, there are 14 transformations.
+      entropy[kSpatial] += VP8LSubSampleSize(width, transform_bits) *
+                           VP8LSubSampleSize(height, transform_bits) *
+                           VP8LFastLog2(14);
+      // For color transforms: 24 as only 3 channels are considered in a
+      // ColorTransformElement.
+      entropy[kSpatialSubGreen] += VP8LSubSampleSize(width, transform_bits) *
+                                   VP8LSubSampleSize(height, transform_bits) *
+                                   VP8LFastLog2(24);
+      // For palettes, add the cost of storing the palette.
+      // We empirically estimate the cost of a compressed entry as 8 bits.
+      // The palette is differential-coded when compressed hence a much
+      // lower cost than sizeof(uint32_t)*8.
+      entropy[kPalette] += palette_size * 8;
+
+      *min_entropy_ix = kDirect;
+      for (k = kDirect + 1; k <= last_mode_to_analyze; ++k) {
+        if (entropy[*min_entropy_ix] > entropy[k]) {
+          *min_entropy_ix = (EntropyIx)k;
+        }
+      }
+      assert((int)*min_entropy_ix <= last_mode_to_analyze);
+      *red_and_blue_always_zero = 1;
+      // Let's check if the histogram of the chosen entropy mode has
+      // non-zero red and blue values. If all are zero, we can later skip
+      // the cross color optimization.
+      {
+        static const uint8_t kHistoPairs[5][2] = {
+          { kHistoRed, kHistoBlue },
+          { kHistoRedPred, kHistoBluePred },
+          { kHistoRedSubGreen, kHistoBlueSubGreen },
+          { kHistoRedPredSubGreen, kHistoBluePredSubGreen },
+          { kHistoRed, kHistoBlue }
+        };
+        const uint32_t* const red_histo =
+            &histo[256 * kHistoPairs[*min_entropy_ix][0]];
+        const uint32_t* const blue_histo =
+            &histo[256 * kHistoPairs[*min_entropy_ix][1]];
+        for (i = 1; i < 256; ++i) {
+          if ((red_histo[i] | blue_histo[i]) != 0) {
+            *red_and_blue_always_zero = 0;
+            break;
+          }
+        }
+      }
+    }
+    WebPSafeFree(histo);
+    return 1;
+  } else {
+    return 0;
+  }
+}
+
+static int GetHistoBits(int method, int use_palette, int width, int height) {
+  // Make tile size a function of encoding method (Range: 0 to 6).
+  int histo_bits = (use_palette ? 9 : 7) - method;
+  while (1) {
+    const int huff_image_size = VP8LSubSampleSize(width, histo_bits) *
+                                VP8LSubSampleSize(height, histo_bits);
+    if (huff_image_size <= MAX_HUFF_IMAGE_SIZE) break;
+    ++histo_bits;
+  }
+  return (histo_bits < MIN_HUFFMAN_BITS) ? MIN_HUFFMAN_BITS :
+         (histo_bits > MAX_HUFFMAN_BITS) ? MAX_HUFFMAN_BITS : histo_bits;
+}
+
+static int GetTransformBits(int method, int histo_bits) {
+  const int max_transform_bits = (method < 4) ? 6 : (method > 4) ? 4 : 5;
+  const int res =
+      (histo_bits > max_transform_bits) ? max_transform_bits : histo_bits;
+  assert(res <= MAX_TRANSFORM_BITS);
+  return res;
+}
+
+// Set of parameters to be used in each iteration of the cruncher.
+#define CRUNCH_SUBCONFIGS_MAX 2
+typedef struct {
+  int lz77_;
+  int do_no_cache_;
+} CrunchSubConfig;
+typedef struct {
+  int entropy_idx_;
+  PaletteSorting palette_sorting_type_;
+  CrunchSubConfig sub_configs_[CRUNCH_SUBCONFIGS_MAX];
+  int sub_configs_size_;
+} CrunchConfig;
+
+// +2 because we add a palette sorting configuration for kPalette and
+// kPaletteAndSpatial.
+#define CRUNCH_CONFIGS_MAX (kNumEntropyIx + 2)
+
+static int EncoderAnalyze(VP8LEncoder* const enc,
+                          CrunchConfig crunch_configs[CRUNCH_CONFIGS_MAX],
+                          int* const crunch_configs_size,
+                          int* const red_and_blue_always_zero) {
+  const WebPPicture* const pic = enc->pic_;
+  const int width = pic->width;
+  const int height = pic->height;
+  const WebPConfig* const config = enc->config_;
+  const int method = config->method;
+  const int low_effort = (config->method == 0);
+  int i;
+  int use_palette;
+  int n_lz77s;
+  // If set to 0, analyze the cache with the computed cache value. If 1, also
+  // analyze with no-cache.
+  int do_no_cache = 0;
+  assert(pic != NULL && pic->argb != NULL);
+
+  // Check whether a palette is possible.
+  enc->palette_size_ = WebPGetColorPalette(pic, enc->palette_sorted_);
+  use_palette = (enc->palette_size_ <= MAX_PALETTE_SIZE);
+  if (!use_palette) {
+    enc->palette_size_ = 0;
+  } else {
+    qsort(enc->palette_sorted_, enc->palette_size_,
+          sizeof(*enc->palette_sorted_), PaletteCompareColorsForQsort);
+  }
+
+  // Empirical bit sizes.
+  enc->histo_bits_ = GetHistoBits(method, use_palette,
+                                  pic->width, pic->height);
+  enc->transform_bits_ = GetTransformBits(method, enc->histo_bits_);
+
+  if (low_effort) {
+    // AnalyzeEntropy is somewhat slow.
+    crunch_configs[0].entropy_idx_ = use_palette ? kPalette : kSpatialSubGreen;
+    crunch_configs[0].palette_sorting_type_ =
+        use_palette ? kSortedDefault : kUnusedPalette;
+    n_lz77s = 1;
+    *crunch_configs_size = 1;
+  } else {
+    EntropyIx min_entropy_ix;
+    // Try out multiple LZ77 on images with few colors.
+    n_lz77s = (enc->palette_size_ > 0 && enc->palette_size_ <= 16) ? 2 : 1;
+    if (!AnalyzeEntropy(pic->argb, width, height, pic->argb_stride, use_palette,
+                        enc->palette_size_, enc->transform_bits_,
+                        &min_entropy_ix, red_and_blue_always_zero)) {
+      return 0;
+    }
+    if (method == 6 && config->quality == 100) {
+      do_no_cache = 1;
+      // Go brute force on all transforms.
+      *crunch_configs_size = 0;
+      for (i = 0; i < kNumEntropyIx; ++i) {
+        // We can only apply kPalette or kPaletteAndSpatial if we can indeed use
+        // a palette.
+        if ((i != kPalette && i != kPaletteAndSpatial) || use_palette) {
+          assert(*crunch_configs_size < CRUNCH_CONFIGS_MAX);
+          crunch_configs[(*crunch_configs_size)].entropy_idx_ = i;
+          if (use_palette && (i == kPalette || i == kPaletteAndSpatial)) {
+            crunch_configs[(*crunch_configs_size)].palette_sorting_type_ =
+                kMinimizeDelta;
+            ++*crunch_configs_size;
+            // Also add modified Zeng's method.
+            crunch_configs[(*crunch_configs_size)].entropy_idx_ = i;
+            crunch_configs[(*crunch_configs_size)].palette_sorting_type_ =
+                kModifiedZeng;
+          } else {
+            crunch_configs[(*crunch_configs_size)].palette_sorting_type_ =
+                kUnusedPalette;
+          }
+          ++*crunch_configs_size;
+        }
+      }
+    } else {
+      // Only choose the guessed best transform.
+      *crunch_configs_size = 1;
+      crunch_configs[0].entropy_idx_ = min_entropy_ix;
+      crunch_configs[0].palette_sorting_type_ =
+          use_palette ? kMinimizeDelta : kUnusedPalette;
+      if (config->quality >= 75 && method == 5) {
+        // Test with and without color cache.
+        do_no_cache = 1;
+        // If we have a palette, also check in combination with spatial.
+        if (min_entropy_ix == kPalette) {
+          *crunch_configs_size = 2;
+          crunch_configs[1].entropy_idx_ = kPaletteAndSpatial;
+          crunch_configs[1].palette_sorting_type_ = kMinimizeDelta;
+        }
+      }
+    }
+  }
+  // Fill in the different LZ77s.
+  assert(n_lz77s <= CRUNCH_SUBCONFIGS_MAX);
+  for (i = 0; i < *crunch_configs_size; ++i) {
+    int j;
+    for (j = 0; j < n_lz77s; ++j) {
+      assert(j < CRUNCH_SUBCONFIGS_MAX);
+      crunch_configs[i].sub_configs_[j].lz77_ =
+          (j == 0) ? kLZ77Standard | kLZ77RLE : kLZ77Box;
+      crunch_configs[i].sub_configs_[j].do_no_cache_ = do_no_cache;
+    }
+    crunch_configs[i].sub_configs_size_ = n_lz77s;
+  }
+  return 1;
+}
+
+static int EncoderInit(VP8LEncoder* const enc) {
+  const WebPPicture* const pic = enc->pic_;
+  const int width = pic->width;
+  const int height = pic->height;
+  const int pix_cnt = width * height;
+  // we round the block size up, so we're guaranteed to have
+  // at most MAX_REFS_BLOCK_PER_IMAGE blocks used:
+  const int refs_block_size = (pix_cnt - 1) / MAX_REFS_BLOCK_PER_IMAGE + 1;
+  int i;
+  if (!VP8LHashChainInit(&enc->hash_chain_, pix_cnt)) return 0;
+
+  for (i = 0; i < 4; ++i) VP8LBackwardRefsInit(&enc->refs_[i], refs_block_size);
+
+  return 1;
+}
+
+// Returns false in case of memory error.
+static int GetHuffBitLengthsAndCodes(
+    const VP8LHistogramSet* const histogram_image,
+    HuffmanTreeCode* const huffman_codes) {
+  int i, k;
+  int ok = 0;
+  uint64_t total_length_size = 0;
+  uint8_t* mem_buf = NULL;
+  const int histogram_image_size = histogram_image->size;
+  int max_num_symbols = 0;
+  uint8_t* buf_rle = NULL;
+  HuffmanTree* huff_tree = NULL;
+
+  // Iterate over all histograms and get the aggregate number of codes used.
+  for (i = 0; i < histogram_image_size; ++i) {
+    const VP8LHistogram* const histo = histogram_image->histograms[i];
+    HuffmanTreeCode* const codes = &huffman_codes[5 * i];
+    assert(histo != NULL);
+    for (k = 0; k < 5; ++k) {
+      const int num_symbols =
+          (k == 0) ? VP8LHistogramNumCodes(histo->palette_code_bits_) :
+          (k == 4) ? NUM_DISTANCE_CODES : 256;
+      codes[k].num_symbols = num_symbols;
+      total_length_size += num_symbols;
+    }
+  }
+
+  // Allocate and Set Huffman codes.
+  {
+    uint16_t* codes;
+    uint8_t* lengths;
+    mem_buf = (uint8_t*)WebPSafeCalloc(total_length_size,
+                                       sizeof(*lengths) + sizeof(*codes));
+    if (mem_buf == NULL) goto End;
+
+    codes = (uint16_t*)mem_buf;
+    lengths = (uint8_t*)&codes[total_length_size];
+    for (i = 0; i < 5 * histogram_image_size; ++i) {
+      const int bit_length = huffman_codes[i].num_symbols;
+      huffman_codes[i].codes = codes;
+      huffman_codes[i].code_lengths = lengths;
+      codes += bit_length;
+      lengths += bit_length;
+      if (max_num_symbols < bit_length) {
+        max_num_symbols = bit_length;
+      }
+    }
+  }
+
+  buf_rle = (uint8_t*)WebPSafeMalloc(1ULL, max_num_symbols);
+  huff_tree = (HuffmanTree*)WebPSafeMalloc(3ULL * max_num_symbols,
+                                           sizeof(*huff_tree));
+  if (buf_rle == NULL || huff_tree == NULL) goto End;
+
+  // Create Huffman trees.
+  for (i = 0; i < histogram_image_size; ++i) {
+    HuffmanTreeCode* const codes = &huffman_codes[5 * i];
+    VP8LHistogram* const histo = histogram_image->histograms[i];
+    VP8LCreateHuffmanTree(histo->literal_, 15, buf_rle, huff_tree, codes + 0);
+    VP8LCreateHuffmanTree(histo->red_, 15, buf_rle, huff_tree, codes + 1);
+    VP8LCreateHuffmanTree(histo->blue_, 15, buf_rle, huff_tree, codes + 2);
+    VP8LCreateHuffmanTree(histo->alpha_, 15, buf_rle, huff_tree, codes + 3);
+    VP8LCreateHuffmanTree(histo->distance_, 15, buf_rle, huff_tree, codes + 4);
+  }
+  ok = 1;
+ End:
+  WebPSafeFree(huff_tree);
+  WebPSafeFree(buf_rle);
+  if (!ok) {
+    WebPSafeFree(mem_buf);
+    memset(huffman_codes, 0, 5 * histogram_image_size * sizeof(*huffman_codes));
+  }
+  return ok;
+}
+
+static void StoreHuffmanTreeOfHuffmanTreeToBitMask(
+    VP8LBitWriter* const bw, const uint8_t* code_length_bitdepth) {
+  // RFC 1951 will calm you down if you are worried about this funny sequence.
+  // This sequence is tuned from that, but more weighted for lower symbol count,
+  // and more spiking histograms.
+  static const uint8_t kStorageOrder[CODE_LENGTH_CODES] = {
+    17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
+  };
+  int i;
+  // Throw away trailing zeros:
+  int codes_to_store = CODE_LENGTH_CODES;
+  for (; codes_to_store > 4; --codes_to_store) {
+    if (code_length_bitdepth[kStorageOrder[codes_to_store - 1]] != 0) {
+      break;
+    }
+  }
+  VP8LPutBits(bw, codes_to_store - 4, 4);
+  for (i = 0; i < codes_to_store; ++i) {
+    VP8LPutBits(bw, code_length_bitdepth[kStorageOrder[i]], 3);
+  }
+}
+
+static void ClearHuffmanTreeIfOnlyOneSymbol(
+    HuffmanTreeCode* const huffman_code) {
+  int k;
+  int count = 0;
+  for (k = 0; k < huffman_code->num_symbols; ++k) {
+    if (huffman_code->code_lengths[k] != 0) {
+      ++count;
+      if (count > 1) return;
+    }
+  }
+  for (k = 0; k < huffman_code->num_symbols; ++k) {
+    huffman_code->code_lengths[k] = 0;
+    huffman_code->codes[k] = 0;
+  }
+}
+
+static void StoreHuffmanTreeToBitMask(
+    VP8LBitWriter* const bw,
+    const HuffmanTreeToken* const tokens, const int num_tokens,
+    const HuffmanTreeCode* const huffman_code) {
+  int i;
+  for (i = 0; i < num_tokens; ++i) {
+    const int ix = tokens[i].code;
+    const int extra_bits = tokens[i].extra_bits;
+    VP8LPutBits(bw, huffman_code->codes[ix], huffman_code->code_lengths[ix]);
+    switch (ix) {
+      case 16:
+        VP8LPutBits(bw, extra_bits, 2);
+        break;
+      case 17:
+        VP8LPutBits(bw, extra_bits, 3);
+        break;
+      case 18:
+        VP8LPutBits(bw, extra_bits, 7);
+        break;
+    }
+  }
+}
+
+// 'huff_tree' and 'tokens' are pre-alloacted buffers.
+static void StoreFullHuffmanCode(VP8LBitWriter* const bw,
+                                 HuffmanTree* const huff_tree,
+                                 HuffmanTreeToken* const tokens,
+                                 const HuffmanTreeCode* const tree) {
+  uint8_t code_length_bitdepth[CODE_LENGTH_CODES] = { 0 };
+  uint16_t code_length_bitdepth_symbols[CODE_LENGTH_CODES] = { 0 };
+  const int max_tokens = tree->num_symbols;
+  int num_tokens;
+  HuffmanTreeCode huffman_code;
+  huffman_code.num_symbols = CODE_LENGTH_CODES;
+  huffman_code.code_lengths = code_length_bitdepth;
+  huffman_code.codes = code_length_bitdepth_symbols;
+
+  VP8LPutBits(bw, 0, 1);
+  num_tokens = VP8LCreateCompressedHuffmanTree(tree, tokens, max_tokens);
+  {
+    uint32_t histogram[CODE_LENGTH_CODES] = { 0 };
+    uint8_t buf_rle[CODE_LENGTH_CODES] = { 0 };
+    int i;
+    for (i = 0; i < num_tokens; ++i) {
+      ++histogram[tokens[i].code];
+    }
+
+    VP8LCreateHuffmanTree(histogram, 7, buf_rle, huff_tree, &huffman_code);
+  }
+
+  StoreHuffmanTreeOfHuffmanTreeToBitMask(bw, code_length_bitdepth);
+  ClearHuffmanTreeIfOnlyOneSymbol(&huffman_code);
+  {
+    int trailing_zero_bits = 0;
+    int trimmed_length = num_tokens;
+    int write_trimmed_length;
+    int length;
+    int i = num_tokens;
+    while (i-- > 0) {
+      const int ix = tokens[i].code;
+      if (ix == 0 || ix == 17 || ix == 18) {
+        --trimmed_length;   // discount trailing zeros
+        trailing_zero_bits += code_length_bitdepth[ix];
+        if (ix == 17) {
+          trailing_zero_bits += 3;
+        } else if (ix == 18) {
+          trailing_zero_bits += 7;
+        }
+      } else {
+        break;
+      }
+    }
+    write_trimmed_length = (trimmed_length > 1 && trailing_zero_bits > 12);
+    length = write_trimmed_length ? trimmed_length : num_tokens;
+    VP8LPutBits(bw, write_trimmed_length, 1);
+    if (write_trimmed_length) {
+      if (trimmed_length == 2) {
+        VP8LPutBits(bw, 0, 3 + 2);     // nbitpairs=1, trimmed_length=2
+      } else {
+        const int nbits = BitsLog2Floor(trimmed_length - 2);
+        const int nbitpairs = nbits / 2 + 1;
+        assert(trimmed_length > 2);
+        assert(nbitpairs - 1 < 8);
+        VP8LPutBits(bw, nbitpairs - 1, 3);
+        VP8LPutBits(bw, trimmed_length - 2, nbitpairs * 2);
+      }
+    }
+    StoreHuffmanTreeToBitMask(bw, tokens, length, &huffman_code);
+  }
+}
+
+// 'huff_tree' and 'tokens' are pre-alloacted buffers.
+static void StoreHuffmanCode(VP8LBitWriter* const bw,
+                             HuffmanTree* const huff_tree,
+                             HuffmanTreeToken* const tokens,
+                             const HuffmanTreeCode* const huffman_code) {
+  int i;
+  int count = 0;
+  int symbols[2] = { 0, 0 };
+  const int kMaxBits = 8;
+  const int kMaxSymbol = 1 << kMaxBits;
+
+  // Check whether it's a small tree.
+  for (i = 0; i < huffman_code->num_symbols && count < 3; ++i) {
+    if (huffman_code->code_lengths[i] != 0) {
+      if (count < 2) symbols[count] = i;
+      ++count;
+    }
+  }
+
+  if (count == 0) {   // emit minimal tree for empty cases
+    // bits: small tree marker: 1, count-1: 0, large 8-bit code: 0, code: 0
+    VP8LPutBits(bw, 0x01, 4);
+  } else if (count <= 2 && symbols[0] < kMaxSymbol && symbols[1] < kMaxSymbol) {
+    VP8LPutBits(bw, 1, 1);  // Small tree marker to encode 1 or 2 symbols.
+    VP8LPutBits(bw, count - 1, 1);
+    if (symbols[0] <= 1) {
+      VP8LPutBits(bw, 0, 1);  // Code bit for small (1 bit) symbol value.
+      VP8LPutBits(bw, symbols[0], 1);
+    } else {
+      VP8LPutBits(bw, 1, 1);
+      VP8LPutBits(bw, symbols[0], 8);
+    }
+    if (count == 2) {
+      VP8LPutBits(bw, symbols[1], 8);
+    }
+  } else {
+    StoreFullHuffmanCode(bw, huff_tree, tokens, huffman_code);
+  }
+}
+
+static WEBP_INLINE void WriteHuffmanCode(VP8LBitWriter* const bw,
+                             const HuffmanTreeCode* const code,
+                             int code_index) {
+  const int depth = code->code_lengths[code_index];
+  const int symbol = code->codes[code_index];
+  VP8LPutBits(bw, symbol, depth);
+}
+
+static WEBP_INLINE void WriteHuffmanCodeWithExtraBits(
+    VP8LBitWriter* const bw,
+    const HuffmanTreeCode* const code,
+    int code_index,
+    int bits,
+    int n_bits) {
+  const int depth = code->code_lengths[code_index];
+  const int symbol = code->codes[code_index];
+  VP8LPutBits(bw, (bits << depth) | symbol, depth + n_bits);
+}
+
+static int StoreImageToBitMask(
+    VP8LBitWriter* const bw, int width, int histo_bits,
+    const VP8LBackwardRefs* const refs,
+    const uint16_t* histogram_symbols,
+    const HuffmanTreeCode* const huffman_codes, const WebPPicture* const pic) {
+  const int histo_xsize = histo_bits ? VP8LSubSampleSize(width, histo_bits) : 1;
+  const int tile_mask = (histo_bits == 0) ? 0 : -(1 << histo_bits);
+  // x and y trace the position in the image.
+  int x = 0;
+  int y = 0;
+  int tile_x = x & tile_mask;
+  int tile_y = y & tile_mask;
+  int histogram_ix = histogram_symbols[0];
+  const HuffmanTreeCode* codes = huffman_codes + 5 * histogram_ix;
+  VP8LRefsCursor c = VP8LRefsCursorInit(refs);
+  while (VP8LRefsCursorOk(&c)) {
+    const PixOrCopy* const v = c.cur_pos;
+    if ((tile_x != (x & tile_mask)) || (tile_y != (y & tile_mask))) {
+      tile_x = x & tile_mask;
+      tile_y = y & tile_mask;
+      histogram_ix = histogram_symbols[(y >> histo_bits) * histo_xsize +
+                                       (x >> histo_bits)];
+      codes = huffman_codes + 5 * histogram_ix;
+    }
+    if (PixOrCopyIsLiteral(v)) {
+      static const uint8_t order[] = { 1, 2, 0, 3 };
+      int k;
+      for (k = 0; k < 4; ++k) {
+        const int code = PixOrCopyLiteral(v, order[k]);
+        WriteHuffmanCode(bw, codes + k, code);
+      }
+    } else if (PixOrCopyIsCacheIdx(v)) {
+      const int code = PixOrCopyCacheIdx(v);
+      const int literal_ix = 256 + NUM_LENGTH_CODES + code;
+      WriteHuffmanCode(bw, codes, literal_ix);
+    } else {
+      int bits, n_bits;
+      int code;
+
+      const int distance = PixOrCopyDistance(v);
+      VP8LPrefixEncode(v->len, &code, &n_bits, &bits);
+      WriteHuffmanCodeWithExtraBits(bw, codes, 256 + code, bits, n_bits);
+
+      // Don't write the distance with the extra bits code since
+      // the distance can be up to 18 bits of extra bits, and the prefix
+      // 15 bits, totaling to 33, and our PutBits only supports up to 32 bits.
+      VP8LPrefixEncode(distance, &code, &n_bits, &bits);
+      WriteHuffmanCode(bw, codes + 4, code);
+      VP8LPutBits(bw, bits, n_bits);
+    }
+    x += PixOrCopyLength(v);
+    while (x >= width) {
+      x -= width;
+      ++y;
+    }
+    VP8LRefsCursorNext(&c);
+  }
+  if (bw->error_) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    return 0;
+  }
+  return 1;
+}
+
+// Special case of EncodeImageInternal() for cache-bits=0, histo_bits=31.
+// pic and percent are for progress.
+static int EncodeImageNoHuffman(VP8LBitWriter* const bw,
+                                const uint32_t* const argb,
+                                VP8LHashChain* const hash_chain,
+                                VP8LBackwardRefs* const refs_array, int width,
+                                int height, int quality, int low_effort,
+                                const WebPPicture* const pic, int percent_range,
+                                int* const percent) {
+  int i;
+  int max_tokens = 0;
+  VP8LBackwardRefs* refs;
+  HuffmanTreeToken* tokens = NULL;
+  HuffmanTreeCode huffman_codes[5] = {{0, NULL, NULL}};
+  const uint16_t histogram_symbols[1] = {0};  // only one tree, one symbol
+  int cache_bits = 0;
+  VP8LHistogramSet* histogram_image = NULL;
+  HuffmanTree* const huff_tree = (HuffmanTree*)WebPSafeMalloc(
+      3ULL * CODE_LENGTH_CODES, sizeof(*huff_tree));
+  if (huff_tree == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  // Calculate backward references from ARGB image.
+  if (!VP8LHashChainFill(hash_chain, quality, argb, width, height, low_effort,
+                         pic, percent_range / 2, percent)) {
+    goto Error;
+  }
+  if (!VP8LGetBackwardReferences(width, height, argb, quality, /*low_effort=*/0,
+                                 kLZ77Standard | kLZ77RLE, cache_bits,
+                                 /*do_no_cache=*/0, hash_chain, refs_array,
+                                 &cache_bits, pic,
+                                 percent_range - percent_range / 2, percent)) {
+    goto Error;
+  }
+  refs = &refs_array[0];
+  histogram_image = VP8LAllocateHistogramSet(1, cache_bits);
+  if (histogram_image == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+  VP8LHistogramSetClear(histogram_image);
+
+  // Build histogram image and symbols from backward references.
+  VP8LHistogramStoreRefs(refs, histogram_image->histograms[0]);
+
+  // Create Huffman bit lengths and codes for each histogram image.
+  assert(histogram_image->size == 1);
+  if (!GetHuffBitLengthsAndCodes(histogram_image, huffman_codes)) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  // No color cache, no Huffman image.
+  VP8LPutBits(bw, 0, 1);
+
+  // Find maximum number of symbols for the huffman tree-set.
+  for (i = 0; i < 5; ++i) {
+    HuffmanTreeCode* const codes = &huffman_codes[i];
+    if (max_tokens < codes->num_symbols) {
+      max_tokens = codes->num_symbols;
+    }
+  }
+
+  tokens = (HuffmanTreeToken*)WebPSafeMalloc(max_tokens, sizeof(*tokens));
+  if (tokens == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  // Store Huffman codes.
+  for (i = 0; i < 5; ++i) {
+    HuffmanTreeCode* const codes = &huffman_codes[i];
+    StoreHuffmanCode(bw, huff_tree, tokens, codes);
+    ClearHuffmanTreeIfOnlyOneSymbol(codes);
+  }
+
+  // Store actual literals.
+  if (!StoreImageToBitMask(bw, width, 0, refs, histogram_symbols, huffman_codes,
+                           pic)) {
+    goto Error;
+  }
+
+ Error:
+  WebPSafeFree(tokens);
+  WebPSafeFree(huff_tree);
+  VP8LFreeHistogramSet(histogram_image);
+  WebPSafeFree(huffman_codes[0].codes);
+  return (pic->error_code == VP8_ENC_OK);
+}
+
+// pic and percent are for progress.
+static int EncodeImageInternal(
+    VP8LBitWriter* const bw, const uint32_t* const argb,
+    VP8LHashChain* const hash_chain, VP8LBackwardRefs refs_array[4], int width,
+    int height, int quality, int low_effort, int use_cache,
+    const CrunchConfig* const config, int* cache_bits, int histogram_bits,
+    size_t init_byte_position, int* const hdr_size, int* const data_size,
+    const WebPPicture* const pic, int percent_range, int* const percent) {
+  const uint32_t histogram_image_xysize =
+      VP8LSubSampleSize(width, histogram_bits) *
+      VP8LSubSampleSize(height, histogram_bits);
+  int remaining_percent = percent_range;
+  int percent_start = *percent;
+  VP8LHistogramSet* histogram_image = NULL;
+  VP8LHistogram* tmp_histo = NULL;
+  int histogram_image_size = 0;
+  size_t bit_array_size = 0;
+  HuffmanTree* const huff_tree = (HuffmanTree*)WebPSafeMalloc(
+      3ULL * CODE_LENGTH_CODES, sizeof(*huff_tree));
+  HuffmanTreeToken* tokens = NULL;
+  HuffmanTreeCode* huffman_codes = NULL;
+  uint16_t* const histogram_symbols = (uint16_t*)WebPSafeMalloc(
+      histogram_image_xysize, sizeof(*histogram_symbols));
+  int sub_configs_idx;
+  int cache_bits_init, write_histogram_image;
+  VP8LBitWriter bw_init = *bw, bw_best;
+  int hdr_size_tmp;
+  VP8LHashChain hash_chain_histogram;  // histogram image hash chain
+  size_t bw_size_best = ~(size_t)0;
+  assert(histogram_bits >= MIN_HUFFMAN_BITS);
+  assert(histogram_bits <= MAX_HUFFMAN_BITS);
+  assert(hdr_size != NULL);
+  assert(data_size != NULL);
+
+  memset(&hash_chain_histogram, 0, sizeof(hash_chain_histogram));
+  if (!VP8LBitWriterInit(&bw_best, 0)) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  // Make sure we can allocate the different objects.
+  if (huff_tree == NULL || histogram_symbols == NULL ||
+      !VP8LHashChainInit(&hash_chain_histogram, histogram_image_xysize)) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  percent_range = remaining_percent / 5;
+  if (!VP8LHashChainFill(hash_chain, quality, argb, width, height,
+                         low_effort, pic, percent_range, percent)) {
+    goto Error;
+  }
+  percent_start += percent_range;
+  remaining_percent -= percent_range;
+
+  if (use_cache) {
+    // If the value is different from zero, it has been set during the
+    // palette analysis.
+    cache_bits_init = (*cache_bits == 0) ? MAX_COLOR_CACHE_BITS : *cache_bits;
+  } else {
+    cache_bits_init = 0;
+  }
+  // If several iterations will happen, clone into bw_best.
+  if ((config->sub_configs_size_ > 1 || config->sub_configs_[0].do_no_cache_) &&
+      !VP8LBitWriterClone(bw, &bw_best)) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  for (sub_configs_idx = 0; sub_configs_idx < config->sub_configs_size_;
+       ++sub_configs_idx) {
+    const CrunchSubConfig* const sub_config =
+        &config->sub_configs_[sub_configs_idx];
+    int cache_bits_best, i_cache;
+    int i_remaining_percent = remaining_percent / config->sub_configs_size_;
+    int i_percent_range = i_remaining_percent / 4;
+    i_remaining_percent -= i_percent_range;
+
+    if (!VP8LGetBackwardReferences(
+            width, height, argb, quality, low_effort, sub_config->lz77_,
+            cache_bits_init, sub_config->do_no_cache_, hash_chain,
+            &refs_array[0], &cache_bits_best, pic, i_percent_range, percent)) {
+      goto Error;
+    }
+
+    for (i_cache = 0; i_cache < (sub_config->do_no_cache_ ? 2 : 1); ++i_cache) {
+      const int cache_bits_tmp = (i_cache == 0) ? cache_bits_best : 0;
+      // Speed-up: no need to study the no-cache case if it was already studied
+      // in i_cache == 0.
+      if (i_cache == 1 && cache_bits_best == 0) break;
+
+      // Reset the bit writer for this iteration.
+      VP8LBitWriterReset(&bw_init, bw);
+
+      // Build histogram image and symbols from backward references.
+      histogram_image =
+          VP8LAllocateHistogramSet(histogram_image_xysize, cache_bits_tmp);
+      tmp_histo = VP8LAllocateHistogram(cache_bits_tmp);
+      if (histogram_image == NULL || tmp_histo == NULL) {
+        WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+        goto Error;
+      }
+
+      i_percent_range = i_remaining_percent / 3;
+      i_remaining_percent -= i_percent_range;
+      if (!VP8LGetHistoImageSymbols(
+              width, height, &refs_array[i_cache], quality, low_effort,
+              histogram_bits, cache_bits_tmp, histogram_image, tmp_histo,
+              histogram_symbols, pic, i_percent_range, percent)) {
+        goto Error;
+      }
+      // Create Huffman bit lengths and codes for each histogram image.
+      histogram_image_size = histogram_image->size;
+      bit_array_size = 5 * histogram_image_size;
+      huffman_codes = (HuffmanTreeCode*)WebPSafeCalloc(bit_array_size,
+                                                       sizeof(*huffman_codes));
+      // Note: some histogram_image entries may point to tmp_histos[], so the
+      // latter need to outlive the following call to
+      // GetHuffBitLengthsAndCodes().
+      if (huffman_codes == NULL ||
+          !GetHuffBitLengthsAndCodes(histogram_image, huffman_codes)) {
+        WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+        goto Error;
+      }
+      // Free combined histograms.
+      VP8LFreeHistogramSet(histogram_image);
+      histogram_image = NULL;
+
+      // Free scratch histograms.
+      VP8LFreeHistogram(tmp_histo);
+      tmp_histo = NULL;
+
+      // Color Cache parameters.
+      if (cache_bits_tmp > 0) {
+        VP8LPutBits(bw, 1, 1);
+        VP8LPutBits(bw, cache_bits_tmp, 4);
+      } else {
+        VP8LPutBits(bw, 0, 1);
+      }
+
+      // Huffman image + meta huffman.
+      write_histogram_image = (histogram_image_size > 1);
+      VP8LPutBits(bw, write_histogram_image, 1);
+      if (write_histogram_image) {
+        uint32_t* const histogram_argb = (uint32_t*)WebPSafeMalloc(
+            histogram_image_xysize, sizeof(*histogram_argb));
+        int max_index = 0;
+        uint32_t i;
+        if (histogram_argb == NULL) {
+          WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+          goto Error;
+        }
+        for (i = 0; i < histogram_image_xysize; ++i) {
+          const int symbol_index = histogram_symbols[i] & 0xffff;
+          histogram_argb[i] = (symbol_index << 8);
+          if (symbol_index >= max_index) {
+            max_index = symbol_index + 1;
+          }
+        }
+        histogram_image_size = max_index;
+
+        VP8LPutBits(bw, histogram_bits - 2, 3);
+        i_percent_range = i_remaining_percent / 2;
+        i_remaining_percent -= i_percent_range;
+        if (!EncodeImageNoHuffman(
+                bw, histogram_argb, &hash_chain_histogram, &refs_array[2],
+                VP8LSubSampleSize(width, histogram_bits),
+                VP8LSubSampleSize(height, histogram_bits), quality, low_effort,
+                pic, i_percent_range, percent)) {
+          WebPSafeFree(histogram_argb);
+          goto Error;
+        }
+        WebPSafeFree(histogram_argb);
+      }
+
+      // Store Huffman codes.
+      {
+        int i;
+        int max_tokens = 0;
+        // Find maximum number of symbols for the huffman tree-set.
+        for (i = 0; i < 5 * histogram_image_size; ++i) {
+          HuffmanTreeCode* const codes = &huffman_codes[i];
+          if (max_tokens < codes->num_symbols) {
+            max_tokens = codes->num_symbols;
+          }
+        }
+        tokens = (HuffmanTreeToken*)WebPSafeMalloc(max_tokens, sizeof(*tokens));
+        if (tokens == NULL) goto Error;
+        for (i = 0; i < 5 * histogram_image_size; ++i) {
+          HuffmanTreeCode* const codes = &huffman_codes[i];
+          StoreHuffmanCode(bw, huff_tree, tokens, codes);
+          ClearHuffmanTreeIfOnlyOneSymbol(codes);
+        }
+      }
+      // Store actual literals.
+      hdr_size_tmp = (int)(VP8LBitWriterNumBytes(bw) - init_byte_position);
+      if (!StoreImageToBitMask(bw, width, histogram_bits, &refs_array[i_cache],
+                               histogram_symbols, huffman_codes, pic)) {
+        goto Error;
+      }
+      // Keep track of the smallest image so far.
+      if (VP8LBitWriterNumBytes(bw) < bw_size_best) {
+        bw_size_best = VP8LBitWriterNumBytes(bw);
+        *cache_bits = cache_bits_tmp;
+        *hdr_size = hdr_size_tmp;
+        *data_size =
+            (int)(VP8LBitWriterNumBytes(bw) - init_byte_position - *hdr_size);
+        VP8LBitWriterSwap(bw, &bw_best);
+      }
+      WebPSafeFree(tokens);
+      tokens = NULL;
+      if (huffman_codes != NULL) {
+        WebPSafeFree(huffman_codes->codes);
+        WebPSafeFree(huffman_codes);
+        huffman_codes = NULL;
+      }
+    }
+  }
+  VP8LBitWriterSwap(bw, &bw_best);
+
+  if (!WebPReportProgress(pic, percent_start + remaining_percent, percent)) {
+    goto Error;
+  }
+
+ Error:
+  WebPSafeFree(tokens);
+  WebPSafeFree(huff_tree);
+  VP8LFreeHistogramSet(histogram_image);
+  VP8LFreeHistogram(tmp_histo);
+  VP8LHashChainClear(&hash_chain_histogram);
+  if (huffman_codes != NULL) {
+    WebPSafeFree(huffman_codes->codes);
+    WebPSafeFree(huffman_codes);
+  }
+  WebPSafeFree(histogram_symbols);
+  VP8LBitWriterWipeOut(&bw_best);
+  return (pic->error_code == VP8_ENC_OK);
+}
+
+// -----------------------------------------------------------------------------
+// Transforms
+
+static void ApplySubtractGreen(VP8LEncoder* const enc, int width, int height,
+                               VP8LBitWriter* const bw) {
+  VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
+  VP8LPutBits(bw, SUBTRACT_GREEN, 2);
+  VP8LSubtractGreenFromBlueAndRed(enc->argb_, width * height);
+}
+
+static int ApplyPredictFilter(const VP8LEncoder* const enc, int width,
+                              int height, int quality, int low_effort,
+                              int used_subtract_green, VP8LBitWriter* const bw,
+                              int percent_range, int* const percent) {
+  const int pred_bits = enc->transform_bits_;
+  const int transform_width = VP8LSubSampleSize(width, pred_bits);
+  const int transform_height = VP8LSubSampleSize(height, pred_bits);
+  // we disable near-lossless quantization if palette is used.
+  const int near_lossless_strength =
+      enc->use_palette_ ? 100 : enc->config_->near_lossless;
+
+  if (!VP8LResidualImage(
+          width, height, pred_bits, low_effort, enc->argb_, enc->argb_scratch_,
+          enc->transform_data_, near_lossless_strength, enc->config_->exact,
+          used_subtract_green, enc->pic_, percent_range / 2, percent)) {
+    return 0;
+  }
+  VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
+  VP8LPutBits(bw, PREDICTOR_TRANSFORM, 2);
+  assert(pred_bits >= 2);
+  VP8LPutBits(bw, pred_bits - 2, 3);
+  return EncodeImageNoHuffman(
+      bw, enc->transform_data_, (VP8LHashChain*)&enc->hash_chain_,
+      (VP8LBackwardRefs*)&enc->refs_[0], transform_width, transform_height,
+      quality, low_effort, enc->pic_, percent_range - percent_range / 2,
+      percent);
+}
+
+static int ApplyCrossColorFilter(const VP8LEncoder* const enc, int width,
+                                 int height, int quality, int low_effort,
+                                 VP8LBitWriter* const bw, int percent_range,
+                                 int* const percent) {
+  const int ccolor_transform_bits = enc->transform_bits_;
+  const int transform_width = VP8LSubSampleSize(width, ccolor_transform_bits);
+  const int transform_height = VP8LSubSampleSize(height, ccolor_transform_bits);
+
+  if (!VP8LColorSpaceTransform(width, height, ccolor_transform_bits, quality,
+                               enc->argb_, enc->transform_data_, enc->pic_,
+                               percent_range / 2, percent)) {
+    return 0;
+  }
+  VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
+  VP8LPutBits(bw, CROSS_COLOR_TRANSFORM, 2);
+  assert(ccolor_transform_bits >= 2);
+  VP8LPutBits(bw, ccolor_transform_bits - 2, 3);
+  return EncodeImageNoHuffman(
+      bw, enc->transform_data_, (VP8LHashChain*)&enc->hash_chain_,
+      (VP8LBackwardRefs*)&enc->refs_[0], transform_width, transform_height,
+      quality, low_effort, enc->pic_, percent_range - percent_range / 2,
+      percent);
+}
+
+// -----------------------------------------------------------------------------
+
+static int WriteRiffHeader(const WebPPicture* const pic, size_t riff_size,
+                           size_t vp8l_size) {
+  uint8_t riff[RIFF_HEADER_SIZE + CHUNK_HEADER_SIZE + VP8L_SIGNATURE_SIZE] = {
+    'R', 'I', 'F', 'F', 0, 0, 0, 0, 'W', 'E', 'B', 'P',
+    'V', 'P', '8', 'L', 0, 0, 0, 0, VP8L_MAGIC_BYTE,
+  };
+  PutLE32(riff + TAG_SIZE, (uint32_t)riff_size);
+  PutLE32(riff + RIFF_HEADER_SIZE + TAG_SIZE, (uint32_t)vp8l_size);
+  return pic->writer(riff, sizeof(riff), pic);
+}
+
+static int WriteImageSize(const WebPPicture* const pic,
+                          VP8LBitWriter* const bw) {
+  const int width = pic->width - 1;
+  const int height = pic->height - 1;
+  assert(width < WEBP_MAX_DIMENSION && height < WEBP_MAX_DIMENSION);
+
+  VP8LPutBits(bw, width, VP8L_IMAGE_SIZE_BITS);
+  VP8LPutBits(bw, height, VP8L_IMAGE_SIZE_BITS);
+  return !bw->error_;
+}
+
+static int WriteRealAlphaAndVersion(VP8LBitWriter* const bw, int has_alpha) {
+  VP8LPutBits(bw, has_alpha, 1);
+  VP8LPutBits(bw, VP8L_VERSION, VP8L_VERSION_BITS);
+  return !bw->error_;
+}
+
+static int WriteImage(const WebPPicture* const pic, VP8LBitWriter* const bw,
+                      size_t* const coded_size) {
+  const uint8_t* const webpll_data = VP8LBitWriterFinish(bw);
+  const size_t webpll_size = VP8LBitWriterNumBytes(bw);
+  const size_t vp8l_size = VP8L_SIGNATURE_SIZE + webpll_size;
+  const size_t pad = vp8l_size & 1;
+  const size_t riff_size = TAG_SIZE + CHUNK_HEADER_SIZE + vp8l_size + pad;
+
+  if (!WriteRiffHeader(pic, riff_size, vp8l_size) ||
+      !pic->writer(webpll_data, webpll_size, pic)) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_WRITE);
+    return 0;
+  }
+
+  if (pad) {
+    const uint8_t pad_byte[1] = { 0 };
+    if (!pic->writer(pad_byte, 1, pic)) {
+      WebPEncodingSetError(pic, VP8_ENC_ERROR_BAD_WRITE);
+      return 0;
+    }
+  }
+  *coded_size = CHUNK_HEADER_SIZE + riff_size;
+  return 1;
+}
+
+// -----------------------------------------------------------------------------
+
+static void ClearTransformBuffer(VP8LEncoder* const enc) {
+  WebPSafeFree(enc->transform_mem_);
+  enc->transform_mem_ = NULL;
+  enc->transform_mem_size_ = 0;
+}
+
+// Allocates the memory for argb (W x H) buffer, 2 rows of context for
+// prediction and transform data.
+// Flags influencing the memory allocated:
+//  enc->transform_bits_
+//  enc->use_predict_, enc->use_cross_color_
+static int AllocateTransformBuffer(VP8LEncoder* const enc, int width,
+                                   int height) {
+  const uint64_t image_size = width * height;
+  // VP8LResidualImage needs room for 2 scanlines of uint32 pixels with an extra
+  // pixel in each, plus 2 regular scanlines of bytes.
+  // TODO(skal): Clean up by using arithmetic in bytes instead of words.
+  const uint64_t argb_scratch_size =
+      enc->use_predict_ ? (width + 1) * 2 + (width * 2 + sizeof(uint32_t) - 1) /
+                                                sizeof(uint32_t)
+                        : 0;
+  const uint64_t transform_data_size =
+      (enc->use_predict_ || enc->use_cross_color_)
+          ? VP8LSubSampleSize(width, enc->transform_bits_) *
+                VP8LSubSampleSize(height, enc->transform_bits_)
+          : 0;
+  const uint64_t max_alignment_in_words =
+      (WEBP_ALIGN_CST + sizeof(uint32_t) - 1) / sizeof(uint32_t);
+  const uint64_t mem_size = image_size + max_alignment_in_words +
+                            argb_scratch_size + max_alignment_in_words +
+                            transform_data_size;
+  uint32_t* mem = enc->transform_mem_;
+  if (mem == NULL || mem_size > enc->transform_mem_size_) {
+    ClearTransformBuffer(enc);
+    mem = (uint32_t*)WebPSafeMalloc(mem_size, sizeof(*mem));
+    if (mem == NULL) {
+      WebPEncodingSetError(enc->pic_, VP8_ENC_ERROR_OUT_OF_MEMORY);
+      return 0;
+    }
+    enc->transform_mem_ = mem;
+    enc->transform_mem_size_ = (size_t)mem_size;
+    enc->argb_content_ = kEncoderNone;
+  }
+  enc->argb_ = mem;
+  mem = (uint32_t*)WEBP_ALIGN(mem + image_size);
+  enc->argb_scratch_ = mem;
+  mem = (uint32_t*)WEBP_ALIGN(mem + argb_scratch_size);
+  enc->transform_data_ = mem;
+
+  enc->current_width_ = width;
+  return 1;
+}
+
+static int MakeInputImageCopy(VP8LEncoder* const enc) {
+  const WebPPicture* const picture = enc->pic_;
+  const int width = picture->width;
+  const int height = picture->height;
+
+  if (!AllocateTransformBuffer(enc, width, height)) return 0;
+  if (enc->argb_content_ == kEncoderARGB) return 1;
+
+  {
+    uint32_t* dst = enc->argb_;
+    const uint32_t* src = picture->argb;
+    int y;
+    for (y = 0; y < height; ++y) {
+      memcpy(dst, src, width * sizeof(*dst));
+      dst += width;
+      src += picture->argb_stride;
+    }
+  }
+  enc->argb_content_ = kEncoderARGB;
+  assert(enc->current_width_ == width);
+  return 1;
+}
+
+// -----------------------------------------------------------------------------
+
+#define APPLY_PALETTE_GREEDY_MAX 4
+
+static WEBP_INLINE uint32_t SearchColorGreedy(const uint32_t palette[],
+                                              int palette_size,
+                                              uint32_t color) {
+  (void)palette_size;
+  assert(palette_size < APPLY_PALETTE_GREEDY_MAX);
+  assert(3 == APPLY_PALETTE_GREEDY_MAX - 1);
+  if (color == palette[0]) return 0;
+  if (color == palette[1]) return 1;
+  if (color == palette[2]) return 2;
+  return 3;
+}
+
+static WEBP_INLINE uint32_t ApplyPaletteHash0(uint32_t color) {
+  // Focus on the green color.
+  return (color >> 8) & 0xff;
+}
+
+#define PALETTE_INV_SIZE_BITS 11
+#define PALETTE_INV_SIZE (1 << PALETTE_INV_SIZE_BITS)
+
+static WEBP_INLINE uint32_t ApplyPaletteHash1(uint32_t color) {
+  // Forget about alpha.
+  return ((uint32_t)((color & 0x00ffffffu) * 4222244071ull)) >>
+         (32 - PALETTE_INV_SIZE_BITS);
+}
+
+static WEBP_INLINE uint32_t ApplyPaletteHash2(uint32_t color) {
+  // Forget about alpha.
+  return ((uint32_t)((color & 0x00ffffffu) * ((1ull << 31) - 1))) >>
+         (32 - PALETTE_INV_SIZE_BITS);
+}
+
+// Use 1 pixel cache for ARGB pixels.
+#define APPLY_PALETTE_FOR(COLOR_INDEX) do {         \
+  uint32_t prev_pix = palette[0];                   \
+  uint32_t prev_idx = 0;                            \
+  for (y = 0; y < height; ++y) {                    \
+    for (x = 0; x < width; ++x) {                   \
+      const uint32_t pix = src[x];                  \
+      if (pix != prev_pix) {                        \
+        prev_idx = COLOR_INDEX;                     \
+        prev_pix = pix;                             \
+      }                                             \
+      tmp_row[x] = prev_idx;                        \
+    }                                               \
+    VP8LBundleColorMap(tmp_row, width, xbits, dst); \
+    src += src_stride;                              \
+    dst += dst_stride;                              \
+  }                                                 \
+} while (0)
+
+// Remap argb values in src[] to packed palettes entries in dst[]
+// using 'row' as a temporary buffer of size 'width'.
+// We assume that all src[] values have a corresponding entry in the palette.
+// Note: src[] can be the same as dst[]
+static int ApplyPalette(const uint32_t* src, uint32_t src_stride, uint32_t* dst,
+                        uint32_t dst_stride, const uint32_t* palette,
+                        int palette_size, int width, int height, int xbits,
+                        const WebPPicture* const pic) {
+  // TODO(skal): this tmp buffer is not needed if VP8LBundleColorMap() can be
+  // made to work in-place.
+  uint8_t* const tmp_row = (uint8_t*)WebPSafeMalloc(width, sizeof(*tmp_row));
+  int x, y;
+
+  if (tmp_row == NULL) {
+    WebPEncodingSetError(pic, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    return 0;
+  }
+
+  if (palette_size < APPLY_PALETTE_GREEDY_MAX) {
+    APPLY_PALETTE_FOR(SearchColorGreedy(palette, palette_size, pix));
+  } else {
+    int i, j;
+    uint16_t buffer[PALETTE_INV_SIZE];
+    uint32_t (*const hash_functions[])(uint32_t) = {
+        ApplyPaletteHash0, ApplyPaletteHash1, ApplyPaletteHash2
+    };
+
+    // Try to find a perfect hash function able to go from a color to an index
+    // within 1 << PALETTE_INV_SIZE_BITS in order to build a hash map to go
+    // from color to index in palette.
+    for (i = 0; i < 3; ++i) {
+      int use_LUT = 1;
+      // Set each element in buffer to max uint16_t.
+      memset(buffer, 0xff, sizeof(buffer));
+      for (j = 0; j < palette_size; ++j) {
+        const uint32_t ind = hash_functions[i](palette[j]);
+        if (buffer[ind] != 0xffffu) {
+          use_LUT = 0;
+          break;
+        } else {
+          buffer[ind] = j;
+        }
+      }
+      if (use_LUT) break;
+    }
+
+    if (i == 0) {
+      APPLY_PALETTE_FOR(buffer[ApplyPaletteHash0(pix)]);
+    } else if (i == 1) {
+      APPLY_PALETTE_FOR(buffer[ApplyPaletteHash1(pix)]);
+    } else if (i == 2) {
+      APPLY_PALETTE_FOR(buffer[ApplyPaletteHash2(pix)]);
+    } else {
+      uint32_t idx_map[MAX_PALETTE_SIZE];
+      uint32_t palette_sorted[MAX_PALETTE_SIZE];
+      PrepareMapToPalette(palette, palette_size, palette_sorted, idx_map);
+      APPLY_PALETTE_FOR(
+          idx_map[SearchColorNoIdx(palette_sorted, pix, palette_size)]);
+    }
+  }
+  WebPSafeFree(tmp_row);
+  return 1;
+}
+#undef APPLY_PALETTE_FOR
+#undef PALETTE_INV_SIZE_BITS
+#undef PALETTE_INV_SIZE
+#undef APPLY_PALETTE_GREEDY_MAX
+
+// Note: Expects "enc->palette_" to be set properly.
+static int MapImageFromPalette(VP8LEncoder* const enc, int in_place) {
+  const WebPPicture* const pic = enc->pic_;
+  const int width = pic->width;
+  const int height = pic->height;
+  const uint32_t* const palette = enc->palette_;
+  const uint32_t* src = in_place ? enc->argb_ : pic->argb;
+  const int src_stride = in_place ? enc->current_width_ : pic->argb_stride;
+  const int palette_size = enc->palette_size_;
+  int xbits;
+
+  // Replace each input pixel by corresponding palette index.
+  // This is done line by line.
+  if (palette_size <= 4) {
+    xbits = (palette_size <= 2) ? 3 : 2;
+  } else {
+    xbits = (palette_size <= 16) ? 1 : 0;
+  }
+
+  if (!AllocateTransformBuffer(enc, VP8LSubSampleSize(width, xbits), height)) {
+    return 0;
+  }
+  if (!ApplyPalette(src, src_stride,
+                     enc->argb_, enc->current_width_,
+                     palette, palette_size, width, height, xbits, pic)) {
+    return 0;
+  }
+  enc->argb_content_ = kEncoderPalette;
+  return 1;
+}
+
+// Save palette_[] to bitstream.
+static WebPEncodingError EncodePalette(VP8LBitWriter* const bw, int low_effort,
+                                       VP8LEncoder* const enc,
+                                       int percent_range, int* const percent) {
+  int i;
+  uint32_t tmp_palette[MAX_PALETTE_SIZE];
+  const int palette_size = enc->palette_size_;
+  const uint32_t* const palette = enc->palette_;
+  VP8LPutBits(bw, TRANSFORM_PRESENT, 1);
+  VP8LPutBits(bw, COLOR_INDEXING_TRANSFORM, 2);
+  assert(palette_size >= 1 && palette_size <= MAX_PALETTE_SIZE);
+  VP8LPutBits(bw, palette_size - 1, 8);
+  for (i = palette_size - 1; i >= 1; --i) {
+    tmp_palette[i] = VP8LSubPixels(palette[i], palette[i - 1]);
+  }
+  tmp_palette[0] = palette[0];
+  return EncodeImageNoHuffman(bw, tmp_palette, &enc->hash_chain_,
+                              &enc->refs_[0], palette_size, 1, /*quality=*/20,
+                              low_effort, enc->pic_, percent_range, percent);
+}
+
+// -----------------------------------------------------------------------------
+// VP8LEncoder
+
+static VP8LEncoder* VP8LEncoderNew(const WebPConfig* const config,
+                                   const WebPPicture* const picture) {
+  VP8LEncoder* const enc = (VP8LEncoder*)WebPSafeCalloc(1ULL, sizeof(*enc));
+  if (enc == NULL) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    return NULL;
+  }
+  enc->config_ = config;
+  enc->pic_ = picture;
+  enc->argb_content_ = kEncoderNone;
+
+  VP8LEncDspInit();
+
+  return enc;
+}
+
+static void VP8LEncoderDelete(VP8LEncoder* enc) {
+  if (enc != NULL) {
+    int i;
+    VP8LHashChainClear(&enc->hash_chain_);
+    for (i = 0; i < 4; ++i) VP8LBackwardRefsClear(&enc->refs_[i]);
+    ClearTransformBuffer(enc);
+    WebPSafeFree(enc);
+  }
+}
+
+// -----------------------------------------------------------------------------
+// Main call
+
+typedef struct {
+  const WebPConfig* config_;
+  const WebPPicture* picture_;
+  VP8LBitWriter* bw_;
+  VP8LEncoder* enc_;
+  int use_cache_;
+  CrunchConfig crunch_configs_[CRUNCH_CONFIGS_MAX];
+  int num_crunch_configs_;
+  int red_and_blue_always_zero_;
+  WebPAuxStats* stats_;
+} StreamEncodeContext;
+
+static int EncodeStreamHook(void* input, void* data2) {
+  StreamEncodeContext* const params = (StreamEncodeContext*)input;
+  const WebPConfig* const config = params->config_;
+  const WebPPicture* const picture = params->picture_;
+  VP8LBitWriter* const bw = params->bw_;
+  VP8LEncoder* const enc = params->enc_;
+  const int use_cache = params->use_cache_;
+  const CrunchConfig* const crunch_configs = params->crunch_configs_;
+  const int num_crunch_configs = params->num_crunch_configs_;
+  const int red_and_blue_always_zero = params->red_and_blue_always_zero_;
+#if !defined(WEBP_DISABLE_STATS)
+  WebPAuxStats* const stats = params->stats_;
+#endif
+  const int quality = (int)config->quality;
+  const int low_effort = (config->method == 0);
+#if (WEBP_NEAR_LOSSLESS == 1)
+  const int width = picture->width;
+#endif
+  const int height = picture->height;
+  const size_t byte_position = VP8LBitWriterNumBytes(bw);
+  int percent = 2;  // for WebPProgressHook
+#if (WEBP_NEAR_LOSSLESS == 1)
+  int use_near_lossless = 0;
+#endif
+  int hdr_size = 0;
+  int data_size = 0;
+  int use_delta_palette = 0;
+  int idx;
+  size_t best_size = ~(size_t)0;
+  VP8LBitWriter bw_init = *bw, bw_best;
+  (void)data2;
+
+  if (!VP8LBitWriterInit(&bw_best, 0) ||
+      (num_crunch_configs > 1 && !VP8LBitWriterClone(bw, &bw_best))) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  for (idx = 0; idx < num_crunch_configs; ++idx) {
+    const int entropy_idx = crunch_configs[idx].entropy_idx_;
+    int remaining_percent = 97 / num_crunch_configs, percent_range;
+    enc->use_palette_ =
+        (entropy_idx == kPalette) || (entropy_idx == kPaletteAndSpatial);
+    enc->use_subtract_green_ =
+        (entropy_idx == kSubGreen) || (entropy_idx == kSpatialSubGreen);
+    enc->use_predict_ = (entropy_idx == kSpatial) ||
+                        (entropy_idx == kSpatialSubGreen) ||
+                        (entropy_idx == kPaletteAndSpatial);
+    // When using a palette, R/B==0, hence no need to test for cross-color.
+    if (low_effort || enc->use_palette_) {
+      enc->use_cross_color_ = 0;
+    } else {
+      enc->use_cross_color_ = red_and_blue_always_zero ? 0 : enc->use_predict_;
+    }
+    // Reset any parameter in the encoder that is set in the previous iteration.
+    enc->cache_bits_ = 0;
+    VP8LBackwardRefsClear(&enc->refs_[0]);
+    VP8LBackwardRefsClear(&enc->refs_[1]);
+
+#if (WEBP_NEAR_LOSSLESS == 1)
+    // Apply near-lossless preprocessing.
+    use_near_lossless = (config->near_lossless < 100) && !enc->use_palette_ &&
+                        !enc->use_predict_;
+    if (use_near_lossless) {
+      if (!AllocateTransformBuffer(enc, width, height)) goto Error;
+      if ((enc->argb_content_ != kEncoderNearLossless) &&
+          !VP8ApplyNearLossless(picture, config->near_lossless, enc->argb_)) {
+        WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+        goto Error;
+      }
+      enc->argb_content_ = kEncoderNearLossless;
+    } else {
+      enc->argb_content_ = kEncoderNone;
+    }
+#else
+    enc->argb_content_ = kEncoderNone;
+#endif
+
+    // Encode palette
+    if (enc->use_palette_) {
+      if (crunch_configs[idx].palette_sorting_type_ == kSortedDefault) {
+        // Nothing to do, we have already sorted the palette.
+        memcpy(enc->palette_, enc->palette_sorted_,
+               enc->palette_size_ * sizeof(*enc->palette_));
+      } else if (crunch_configs[idx].palette_sorting_type_ == kMinimizeDelta) {
+        PaletteSortMinimizeDeltas(enc->palette_sorted_, enc->palette_size_,
+                                  enc->palette_);
+      } else {
+        assert(crunch_configs[idx].palette_sorting_type_ == kModifiedZeng);
+        if (!PaletteSortModifiedZeng(enc->pic_, enc->palette_sorted_,
+                                      enc->palette_size_, enc->palette_)) {
+          goto Error;
+        }
+      }
+      percent_range = remaining_percent / 4;
+      if (!EncodePalette(bw, low_effort, enc, percent_range, &percent)) {
+        goto Error;
+      }
+      remaining_percent -= percent_range;
+      if (!MapImageFromPalette(enc, use_delta_palette)) goto Error;
+      // If using a color cache, do not have it bigger than the number of
+      // colors.
+      if (use_cache && enc->palette_size_ < (1 << MAX_COLOR_CACHE_BITS)) {
+        enc->cache_bits_ = BitsLog2Floor(enc->palette_size_) + 1;
+      }
+    }
+    if (!use_delta_palette) {
+      // In case image is not packed.
+      if (enc->argb_content_ != kEncoderNearLossless &&
+          enc->argb_content_ != kEncoderPalette) {
+        if (!MakeInputImageCopy(enc)) goto Error;
+      }
+
+      // -----------------------------------------------------------------------
+      // Apply transforms and write transform data.
+
+      if (enc->use_subtract_green_) {
+        ApplySubtractGreen(enc, enc->current_width_, height, bw);
+      }
+
+      if (enc->use_predict_) {
+        percent_range = remaining_percent / 3;
+        if (!ApplyPredictFilter(enc, enc->current_width_, height, quality,
+                                low_effort, enc->use_subtract_green_, bw,
+                                percent_range, &percent)) {
+          goto Error;
+        }
+        remaining_percent -= percent_range;
+      }
+
+      if (enc->use_cross_color_) {
+        percent_range = remaining_percent / 2;
+        if (!ApplyCrossColorFilter(enc, enc->current_width_, height, quality,
+                                   low_effort, bw, percent_range, &percent)) {
+          goto Error;
+        }
+        remaining_percent -= percent_range;
+      }
+    }
+
+    VP8LPutBits(bw, !TRANSFORM_PRESENT, 1);  // No more transforms.
+
+    // -------------------------------------------------------------------------
+    // Encode and write the transformed image.
+    if (!EncodeImageInternal(
+            bw, enc->argb_, &enc->hash_chain_, enc->refs_, enc->current_width_,
+            height, quality, low_effort, use_cache, &crunch_configs[idx],
+            &enc->cache_bits_, enc->histo_bits_, byte_position, &hdr_size,
+            &data_size, picture, remaining_percent, &percent)) {
+      goto Error;
+    }
+
+    // If we are better than what we already have.
+    if (VP8LBitWriterNumBytes(bw) < best_size) {
+      best_size = VP8LBitWriterNumBytes(bw);
+      // Store the BitWriter.
+      VP8LBitWriterSwap(bw, &bw_best);
+#if !defined(WEBP_DISABLE_STATS)
+      // Update the stats.
+      if (stats != NULL) {
+        stats->lossless_features = 0;
+        if (enc->use_predict_) stats->lossless_features |= 1;
+        if (enc->use_cross_color_) stats->lossless_features |= 2;
+        if (enc->use_subtract_green_) stats->lossless_features |= 4;
+        if (enc->use_palette_) stats->lossless_features |= 8;
+        stats->histogram_bits = enc->histo_bits_;
+        stats->transform_bits = enc->transform_bits_;
+        stats->cache_bits = enc->cache_bits_;
+        stats->palette_size = enc->palette_size_;
+        stats->lossless_size = (int)(best_size - byte_position);
+        stats->lossless_hdr_size = hdr_size;
+        stats->lossless_data_size = data_size;
+      }
+#endif
+    }
+    // Reset the bit writer for the following iteration if any.
+    if (num_crunch_configs > 1) VP8LBitWriterReset(&bw_init, bw);
+  }
+  VP8LBitWriterSwap(&bw_best, bw);
+
+ Error:
+  VP8LBitWriterWipeOut(&bw_best);
+  // The hook should return false in case of error.
+  return (params->picture_->error_code == VP8_ENC_OK);
+}
+
+int VP8LEncodeStream(const WebPConfig* const config,
+                     const WebPPicture* const picture,
+                     VP8LBitWriter* const bw_main, int use_cache) {
+  VP8LEncoder* const enc_main = VP8LEncoderNew(config, picture);
+  VP8LEncoder* enc_side = NULL;
+  CrunchConfig crunch_configs[CRUNCH_CONFIGS_MAX];
+  int num_crunch_configs_main, num_crunch_configs_side = 0;
+  int idx;
+  int red_and_blue_always_zero = 0;
+  WebPWorker worker_main, worker_side;
+  StreamEncodeContext params_main, params_side;
+  // The main thread uses picture->stats, the side thread uses stats_side.
+  WebPAuxStats stats_side;
+  VP8LBitWriter bw_side;
+  WebPPicture picture_side;
+  const WebPWorkerInterface* const worker_interface = WebPGetWorkerInterface();
+  int ok_main;
+
+  if (enc_main == NULL || !VP8LBitWriterInit(&bw_side, 0)) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    VP8LEncoderDelete(enc_main);
+    return 0;
+  }
+
+  // Avoid "garbage value" error from Clang's static analysis tool.
+  WebPPictureInit(&picture_side);
+
+  // Analyze image (entropy, num_palettes etc)
+  if (!EncoderAnalyze(enc_main, crunch_configs, &num_crunch_configs_main,
+                      &red_and_blue_always_zero) ||
+      !EncoderInit(enc_main)) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  // Split the configs between the main and side threads (if any).
+  if (config->thread_level > 0) {
+    num_crunch_configs_side = num_crunch_configs_main / 2;
+    for (idx = 0; idx < num_crunch_configs_side; ++idx) {
+      params_side.crunch_configs_[idx] =
+          crunch_configs[num_crunch_configs_main - num_crunch_configs_side +
+                         idx];
+    }
+    params_side.num_crunch_configs_ = num_crunch_configs_side;
+  }
+  num_crunch_configs_main -= num_crunch_configs_side;
+  for (idx = 0; idx < num_crunch_configs_main; ++idx) {
+    params_main.crunch_configs_[idx] = crunch_configs[idx];
+  }
+  params_main.num_crunch_configs_ = num_crunch_configs_main;
+
+  // Fill in the parameters for the thread workers.
+  {
+    const int params_size = (num_crunch_configs_side > 0) ? 2 : 1;
+    for (idx = 0; idx < params_size; ++idx) {
+      // Create the parameters for each worker.
+      WebPWorker* const worker = (idx == 0) ? &worker_main : &worker_side;
+      StreamEncodeContext* const param =
+          (idx == 0) ? &params_main : &params_side;
+      param->config_ = config;
+      param->use_cache_ = use_cache;
+      param->red_and_blue_always_zero_ = red_and_blue_always_zero;
+      if (idx == 0) {
+        param->picture_ = picture;
+        param->stats_ = picture->stats;
+        param->bw_ = bw_main;
+        param->enc_ = enc_main;
+      } else {
+        // Create a side picture (error_code is not thread-safe).
+        if (!WebPPictureView(picture, /*left=*/0, /*top=*/0, picture->width,
+                             picture->height, &picture_side)) {
+          assert(0);
+        }
+        picture_side.progress_hook = NULL;  // Progress hook is not thread-safe.
+        param->picture_ = &picture_side;  // No need to free a view afterwards.
+        param->stats_ = (picture->stats == NULL) ? NULL : &stats_side;
+        // Create a side bit writer.
+        if (!VP8LBitWriterClone(bw_main, &bw_side)) {
+          WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+          goto Error;
+        }
+        param->bw_ = &bw_side;
+        // Create a side encoder.
+        enc_side = VP8LEncoderNew(config, &picture_side);
+        if (enc_side == NULL || !EncoderInit(enc_side)) {
+          WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+          goto Error;
+        }
+        // Copy the values that were computed for the main encoder.
+        enc_side->histo_bits_ = enc_main->histo_bits_;
+        enc_side->transform_bits_ = enc_main->transform_bits_;
+        enc_side->palette_size_ = enc_main->palette_size_;
+        memcpy(enc_side->palette_, enc_main->palette_,
+               sizeof(enc_main->palette_));
+        memcpy(enc_side->palette_sorted_, enc_main->palette_sorted_,
+               sizeof(enc_main->palette_sorted_));
+        param->enc_ = enc_side;
+      }
+      // Create the workers.
+      worker_interface->Init(worker);
+      worker->data1 = param;
+      worker->data2 = NULL;
+      worker->hook = EncodeStreamHook;
+    }
+  }
+
+  // Start the second thread if needed.
+  if (num_crunch_configs_side != 0) {
+    if (!worker_interface->Reset(&worker_side)) {
+      WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+      goto Error;
+    }
+#if !defined(WEBP_DISABLE_STATS)
+    // This line is here and not in the param initialization above to remove a
+    // Clang static analyzer warning.
+    if (picture->stats != NULL) {
+      memcpy(&stats_side, picture->stats, sizeof(stats_side));
+    }
+#endif
+    worker_interface->Launch(&worker_side);
+  }
+  // Execute the main thread.
+  worker_interface->Execute(&worker_main);
+  ok_main = worker_interface->Sync(&worker_main);
+  worker_interface->End(&worker_main);
+  if (num_crunch_configs_side != 0) {
+    // Wait for the second thread.
+    const int ok_side = worker_interface->Sync(&worker_side);
+    worker_interface->End(&worker_side);
+    if (!ok_main || !ok_side) {
+      if (picture->error_code == VP8_ENC_OK) {
+        assert(picture_side.error_code != VP8_ENC_OK);
+        WebPEncodingSetError(picture, picture_side.error_code);
+      }
+      goto Error;
+    }
+    if (VP8LBitWriterNumBytes(&bw_side) < VP8LBitWriterNumBytes(bw_main)) {
+      VP8LBitWriterSwap(bw_main, &bw_side);
+#if !defined(WEBP_DISABLE_STATS)
+      if (picture->stats != NULL) {
+        memcpy(picture->stats, &stats_side, sizeof(*picture->stats));
+      }
+#endif
+    }
+  }
+
+ Error:
+  VP8LBitWriterWipeOut(&bw_side);
+  VP8LEncoderDelete(enc_main);
+  VP8LEncoderDelete(enc_side);
+  return (picture->error_code == VP8_ENC_OK);
+}
+
+#undef CRUNCH_CONFIGS_MAX
+#undef CRUNCH_SUBCONFIGS_MAX
+
+int VP8LEncodeImage(const WebPConfig* const config,
+                    const WebPPicture* const picture) {
+  int width, height;
+  int has_alpha;
+  size_t coded_size;
+  int percent = 0;
+  int initial_size;
+  VP8LBitWriter bw;
+
+  if (picture == NULL) return 0;
+
+  if (config == NULL || picture->argb == NULL) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER);
+    return 0;
+  }
+
+  width = picture->width;
+  height = picture->height;
+  // Initialize BitWriter with size corresponding to 16 bpp to photo images and
+  // 8 bpp for graphical images.
+  initial_size = (config->image_hint == WEBP_HINT_GRAPH) ?
+      width * height : width * height * 2;
+  if (!VP8LBitWriterInit(&bw, initial_size)) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  if (!WebPReportProgress(picture, 1, &percent)) {
+ UserAbort:
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_USER_ABORT);
+    goto Error;
+  }
+  // Reset stats (for pure lossless coding)
+  if (picture->stats != NULL) {
+    WebPAuxStats* const stats = picture->stats;
+    memset(stats, 0, sizeof(*stats));
+    stats->PSNR[0] = 99.f;
+    stats->PSNR[1] = 99.f;
+    stats->PSNR[2] = 99.f;
+    stats->PSNR[3] = 99.f;
+    stats->PSNR[4] = 99.f;
+  }
+
+  // Write image size.
+  if (!WriteImageSize(picture, &bw)) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  has_alpha = WebPPictureHasTransparency(picture);
+  // Write the non-trivial Alpha flag and lossless version.
+  if (!WriteRealAlphaAndVersion(&bw, has_alpha)) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+    goto Error;
+  }
+
+  if (!WebPReportProgress(picture, 2, &percent)) goto UserAbort;
+
+  // Encode main image stream.
+  if (!VP8LEncodeStream(config, picture, &bw, 1 /*use_cache*/)) goto Error;
+
+  if (!WebPReportProgress(picture, 99, &percent)) goto UserAbort;
+
+  // Finish the RIFF chunk.
+  if (!WriteImage(picture, &bw, &coded_size)) goto Error;
+
+  if (!WebPReportProgress(picture, 100, &percent)) goto UserAbort;
+
+#if !defined(WEBP_DISABLE_STATS)
+  // Save size.
+  if (picture->stats != NULL) {
+    picture->stats->coded_size += (int)coded_size;
+    picture->stats->lossless_size = (int)coded_size;
+  }
+#endif
+
+  if (picture->extra_info != NULL) {
+    const int mb_w = (width + 15) >> 4;
+    const int mb_h = (height + 15) >> 4;
+    memset(picture->extra_info, 0, mb_w * mb_h * sizeof(*picture->extra_info));
+  }
+
+ Error:
+  if (bw.error_) {
+    WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY);
+  }
+  VP8LBitWriterWipeOut(&bw);
+  return (picture->error_code == VP8_ENC_OK);
+}
+
+//------------------------------------------------------------------------------