Alpha coding: reorganize the filter/unfiltering code

Move the filtering code to their own dsp/ spot
New function: VP8FiltersInit()

Change-Id: I0b2041eab42346c59b972f2575b05509e6a8f7b1

Android.mk

@@ -51,6 +51,7 @@ LOCAL_SRC_FILES := \
     src/dsp/enc_mips_dsp_r2.c \
     src/dsp/enc_neon.$(NEON) \
     src/dsp/enc_sse2.c \
+    src/dsp/filters.c \
     src/dsp/filters_mips_dsp_r2.c \
     src/dsp/lossless.c \
     src/dsp/lossless_mips32.c \

Makefile.vc

@@ -195,6 +195,7 @@ DSP_DEC_OBJS = \
     $(DIROBJ)\dsp\dec_mips_dsp_r2.obj \
     $(DIROBJ)\dsp\dec_neon.obj \
     $(DIROBJ)\dsp\dec_sse2.obj \
+    $(DIROBJ)\dsp\filters.obj \
     $(DIROBJ)\dsp\filters_mips_dsp_r2.obj \
     $(DIROBJ)\dsp\lossless.obj \
     $(DIROBJ)\dsp\lossless_mips32.obj \

makefile.unix

@@ -119,6 +119,7 @@ DSP_DEC_OBJS = \
     src/dsp/dec_mips_dsp_r2.o \
     src/dsp/dec_neon.o \
     src/dsp/dec_sse2.o \
+    src/dsp/filters.o \
     src/dsp/filters_mips_dsp_r2.o \
     src/dsp/lossless.o \
     src/dsp/lossless_mips32.o \

src/dec/alpha.c

@@ -15,6 +15,7 @@
 #include "./alphai.h"
 #include "./vp8i.h"
 #include "./vp8li.h"
+#include "../dsp/dsp.h"
 #include "../utils/quant_levels_dec.h"
 #include "../utils/utils.h"
 #include "../webp/format_constants.h"
@@ -78,6 +79,7 @@ static int ALPHInit(ALPHDecoder* const dec, const uint8_t* data,
     assert(dec->method_ == ALPHA_LOSSLESS_COMPRESSION);
     ok = VP8LDecodeAlphaHeader(dec, alpha_data, alpha_data_size, output);
   }
+  VP8FiltersInit();
   return ok;
 }
 

src/dsp/Makefile.am

@@ -18,6 +18,7 @@ COMMON_SOURCES += dec_mips32.c
 COMMON_SOURCES += dec_mips_dsp_r2.c
 COMMON_SOURCES += dec_neon.c
 COMMON_SOURCES += dsp.h
+COMMON_SOURCES += filters.c
 COMMON_SOURCES += filters_mips_dsp_r2.c
 COMMON_SOURCES += lossless.c
 COMMON_SOURCES += lossless.h

src/dsp/alpha_processing.c

@@ -343,7 +343,6 @@ int (*WebPExtractAlpha)(const uint8_t*, int, int, int, uint8_t*, int);
 //------------------------------------------------------------------------------
 // Init function
 
-extern void VP8FiltersInitMIPSdspR2(void);
 extern void WebPInitAlphaProcessingMIPSdspR2(void);
 extern void WebPInitAlphaProcessingSSE2(void);
 
@@ -370,7 +369,6 @@ WEBP_TSAN_IGNORE_FUNCTION void WebPInitAlphaProcessing(void) {
 #endif
 #if defined(WEBP_USE_MIPS_DSP_R2)
     if (VP8GetCPUInfo(kMIPSdspR2)) {
-      VP8FiltersInitMIPSdspR2();
       WebPInitAlphaProcessingMIPSdspR2();
     }
 #endif

src/dsp/dsp.h

@@ -373,6 +373,39 @@ extern void (*VP8PackRGB)(const uint8_t* r, const uint8_t* g, const uint8_t* b,
 // To be called first before using the above.
 WEBP_TSAN_IGNORE_FUNCTION void VP8EncDspARGBInit(void);
 
+//------------------------------------------------------------------------------
+// Filter functions
+
+typedef enum {     // Filter types.
+  WEBP_FILTER_NONE = 0,
+  WEBP_FILTER_HORIZONTAL,
+  WEBP_FILTER_VERTICAL,
+  WEBP_FILTER_GRADIENT,
+  WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
+  WEBP_FILTER_BEST,    // meta-types
+  WEBP_FILTER_FAST
+} WEBP_FILTER_TYPE;
+
+typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
+                               int stride, uint8_t* out);
+typedef void (*WebPUnfilterFunc)(int width, int height, int stride,
+                                 int row, int num_rows, uint8_t* data);
+
+// Filter the given data using the given predictor.
+// 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
+// in raster order.
+// 'stride' is number of bytes per scan line (with possible padding).
+// 'out' should be pre-allocated.
+extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
+
+// In-place reconstruct the original data from the given filtered data.
+// The reconstruction will be done for 'num_rows' rows starting from 'row'
+// (assuming rows upto 'row - 1' are already reconstructed).
+extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
+
+// To be called first before using the above.
+WEBP_TSAN_IGNORE_FUNCTION void VP8FiltersInit(void);
+
 #ifdef __cplusplus
 }    // extern "C"
 #endif

src/dsp/filters.c

@@ -0,0 +1,234 @@
+// Copyright 2011 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.
+// -----------------------------------------------------------------------------
+//
+// Spatial prediction using various filters
+//
+// Author: Urvang (urvang@google.com)
+
+#include "./dsp.h"
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+//------------------------------------------------------------------------------
+// Helpful macro.
+
+# define SANITY_CHECK(in, out)                                                 \
+  assert(in != NULL);                                                          \
+  assert(out != NULL);                                                         \
+  assert(width > 0);                                                           \
+  assert(height > 0);                                                          \
+  assert(stride >= width);                                                     \
+  assert(row >= 0 && num_rows > 0 && row + num_rows <= height);                \
+  (void)height;  // Silence unused warning.
+
+static WEBP_INLINE void PredictLine(const uint8_t* src, const uint8_t* pred,
+                                    uint8_t* dst, int length, int inverse) {
+  int i;
+  if (inverse) {
+    for (i = 0; i < length; ++i) dst[i] = src[i] + pred[i];
+  } else {
+    for (i = 0; i < length; ++i) dst[i] = src[i] - pred[i];
+  }
+}
+
+//------------------------------------------------------------------------------
+// Horizontal filter.
+
+static WEBP_INLINE void DoHorizontalFilter(const uint8_t* in,
+                                           int width, int height, int stride,
+                                           int row, int num_rows,
+                                           int inverse, uint8_t* out) {
+  const uint8_t* preds;
+  const size_t start_offset = row * stride;
+  const int last_row = row + num_rows;
+  SANITY_CHECK(in, out);
+  in += start_offset;
+  out += start_offset;
+  preds = inverse ? out : in;
+
+  if (row == 0) {
+    // Leftmost pixel is the same as input for topmost scanline.
+    out[0] = in[0];
+    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+    row = 1;
+    preds += stride;
+    in += stride;
+    out += stride;
+  }
+
+  // Filter line-by-line.
+  while (row < last_row) {
+    // Leftmost pixel is predicted from above.
+    PredictLine(in, preds - stride, out, 1, inverse);
+    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+    ++row;
+    preds += stride;
+    in += stride;
+    out += stride;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Vertical filter.
+
+static WEBP_INLINE void DoVerticalFilter(const uint8_t* in,
+                                         int width, int height, int stride,
+                                         int row, int num_rows,
+                                         int inverse, uint8_t* out) {
+  const uint8_t* preds;
+  const size_t start_offset = row * stride;
+  const int last_row = row + num_rows;
+  SANITY_CHECK(in, out);
+  in += start_offset;
+  out += start_offset;
+  preds = inverse ? out : in;
+
+  if (row == 0) {
+    // Very first top-left pixel is copied.
+    out[0] = in[0];
+    // Rest of top scan-line is left-predicted.
+    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+    row = 1;
+    in += stride;
+    out += stride;
+  } else {
+    // We are starting from in-between. Make sure 'preds' points to prev row.
+    preds -= stride;
+  }
+
+  // Filter line-by-line.
+  while (row < last_row) {
+    PredictLine(in, preds, out, width, inverse);
+    ++row;
+    preds += stride;
+    in += stride;
+    out += stride;
+  }
+}
+
+//------------------------------------------------------------------------------
+// Gradient filter.
+
+static WEBP_INLINE int GradientPredictor(uint8_t a, uint8_t b, uint8_t c) {
+  const int g = a + b - c;
+  return ((g & ~0xff) == 0) ? g : (g < 0) ? 0 : 255;  // clip to 8bit
+}
+
+static WEBP_INLINE void DoGradientFilter(const uint8_t* in,
+                                         int width, int height, int stride,
+                                         int row, int num_rows,
+                                         int inverse, uint8_t* out) {
+  const uint8_t* preds;
+  const size_t start_offset = row * stride;
+  const int last_row = row + num_rows;
+  SANITY_CHECK(in, out);
+  in += start_offset;
+  out += start_offset;
+  preds = inverse ? out : in;
+
+  // left prediction for top scan-line
+  if (row == 0) {
+    out[0] = in[0];
+    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
+    row = 1;
+    preds += stride;
+    in += stride;
+    out += stride;
+  }
+
+  // Filter line-by-line.
+  while (row < last_row) {
+    int w;
+    // leftmost pixel: predict from above.
+    PredictLine(in, preds - stride, out, 1, inverse);
+    for (w = 1; w < width; ++w) {
+      const int pred = GradientPredictor(preds[w - 1],
+                                         preds[w - stride],
+                                         preds[w - stride - 1]);
+      out[w] = in[w] + (inverse ? pred : -pred);
+    }
+    ++row;
+    preds += stride;
+    in += stride;
+    out += stride;
+  }
+}
+
+#undef SANITY_CHECK
+
+//------------------------------------------------------------------------------
+
+static void HorizontalFilter(const uint8_t* data, int width, int height,
+                             int stride, uint8_t* filtered_data) {
+  DoHorizontalFilter(data, width, height, stride, 0, height, 0, filtered_data);
+}
+
+static void VerticalFilter(const uint8_t* data, int width, int height,
+                           int stride, uint8_t* filtered_data) {
+  DoVerticalFilter(data, width, height, stride, 0, height, 0, filtered_data);
+}
+
+
+static void GradientFilter(const uint8_t* data, int width, int height,
+                           int stride, uint8_t* filtered_data) {
+  DoGradientFilter(data, width, height, stride, 0, height, 0, filtered_data);
+}
+
+
+//------------------------------------------------------------------------------
+
+static void VerticalUnfilter(int width, int height, int stride, int row,
+                             int num_rows, uint8_t* data) {
+  DoVerticalFilter(data, width, height, stride, row, num_rows, 1, data);
+}
+
+static void HorizontalUnfilter(int width, int height, int stride, int row,
+                               int num_rows, uint8_t* data) {
+  DoHorizontalFilter(data, width, height, stride, row, num_rows, 1, data);
+}
+
+static void GradientUnfilter(int width, int height, int stride, int row,
+                             int num_rows, uint8_t* data) {
+  DoGradientFilter(data, width, height, stride, row, num_rows, 1, data);
+}
+
+//------------------------------------------------------------------------------
+// Init function
+
+WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
+WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
+
+extern void VP8FiltersInitMIPSdspR2(void);
+
+static volatile VP8CPUInfo filters_last_cpuinfo_used =
+    (VP8CPUInfo)&filters_last_cpuinfo_used;
+
+WEBP_TSAN_IGNORE_FUNCTION void VP8FiltersInit(void) {
+  if (filters_last_cpuinfo_used == VP8GetCPUInfo) return;
+
+  WebPUnfilters[WEBP_FILTER_NONE] = NULL;
+  WebPUnfilters[WEBP_FILTER_HORIZONTAL] = HorizontalUnfilter;
+  WebPUnfilters[WEBP_FILTER_VERTICAL] = VerticalUnfilter;
+  WebPUnfilters[WEBP_FILTER_GRADIENT] = GradientUnfilter;
+
+  WebPFilters[WEBP_FILTER_NONE] = NULL;
+  WebPFilters[WEBP_FILTER_HORIZONTAL] = HorizontalFilter;
+  WebPFilters[WEBP_FILTER_VERTICAL] = VerticalFilter;
+  WebPFilters[WEBP_FILTER_GRADIENT] = GradientFilter;
+
+  if (VP8GetCPUInfo != NULL) {
+#if defined(WEBP_USE_MIPS_DSP_R2)
+    if (VP8GetCPUInfo(kMIPSdspR2)) {
+      VP8FiltersInitMIPSdspR2();
+    }
+#endif
+  }
+  filters_last_cpuinfo_used = VP8GetCPUInfo;
+}

src/dsp/filters_mips_dsp_r2.c

@@ -16,7 +16,7 @@
 
 #if defined(WEBP_USE_MIPS_DSP_R2)
 
-#include "../utils/filters.h"
+#include "../dsp/dsp.h"
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>

src/enc/alpha.c

@@ -15,6 +15,7 @@
 #include <stdlib.h>
 
 #include "./vp8enci.h"
+#include "../dsp/dsp.h"
 #include "../utils/filters.h"
 #include "../utils/quant_levels.h"
 #include "../utils/utils.h"
@@ -208,8 +209,9 @@ static uint32_t GetFilterMap(const uint8_t* alpha, int width, int height,
     const int kMaxColorsForFilterNone = 192;
     const int num_colors = GetNumColors(alpha, width, height, width);
     // For low number of colors, NONE yields better compression.
-    filter = (num_colors <= kMinColorsForFilterNone) ? WEBP_FILTER_NONE :
+    filter = (num_colors <= kMinColorsForFilterNone)
-             EstimateBestFilter(alpha, width, height, width);
+        ? WEBP_FILTER_NONE
+        : WebPEstimateBestFilter(alpha, width, height, width);
     bit_map |= 1 << filter;
     // For large number of colors, try FILTER_NONE in addition to the best
     // filter as well.
@@ -240,6 +242,7 @@ static int ApplyFiltersAndEncode(const uint8_t* alpha, int width, int height,
   uint32_t try_map =
       GetFilterMap(alpha, width, height, filter, effort_level);
   InitFilterTrial(&best);
+
   if (try_map != FILTER_TRY_NONE) {
     uint8_t* filtered_alpha =  (uint8_t*)WebPSafeMalloc(1ULL, data_size);
     if (filtered_alpha == NULL) return 0;
@@ -326,6 +329,7 @@ static int EncodeAlpha(VP8Encoder* const enc,
   }
 
   if (ok) {
+    VP8FiltersInit();
     ok = ApplyFiltersAndEncode(quant_alpha, width, height, data_size, method,
                                filter, reduce_levels, effort_level, output,
                                output_size, pic->stats);

src/utils/filters.c

@@ -7,199 +7,26 @@
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
-// Spatial prediction using various filters
+// filter estimation
 //
 // Author: Urvang (urvang@google.com)
 
 #include "./filters.h"
-#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
-//------------------------------------------------------------------------------
-// Helpful macro.
-
-# define SANITY_CHECK(in, out)                                                 \
-  assert(in != NULL);                                                          \
-  assert(out != NULL);                                                         \
-  assert(width > 0);                                                           \
-  assert(height > 0);                                                          \
-  assert(stride >= width);                                                     \
-  assert(row >= 0 && num_rows > 0 && row + num_rows <= height);                \
-  (void)height;  // Silence unused warning.
-
-static WEBP_INLINE void PredictLine(const uint8_t* src, const uint8_t* pred,
-                                    uint8_t* dst, int length, int inverse) {
-  int i;
-  if (inverse) {
-    for (i = 0; i < length; ++i) dst[i] = src[i] + pred[i];
-  } else {
-    for (i = 0; i < length; ++i) dst[i] = src[i] - pred[i];
-  }
-}
-
-//------------------------------------------------------------------------------
-// Horizontal filter.
-
-static WEBP_INLINE void DoHorizontalFilter(const uint8_t* in,
-                                           int width, int height, int stride,
-                                           int row, int num_rows,
-                                           int inverse, uint8_t* out) {
-  const uint8_t* preds;
-  const size_t start_offset = row * stride;
-  const int last_row = row + num_rows;
-  SANITY_CHECK(in, out);
-  in += start_offset;
-  out += start_offset;
-  preds = inverse ? out : in;
-
-  if (row == 0) {
-    // Leftmost pixel is the same as input for topmost scanline.
-    out[0] = in[0];
-    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
-    row = 1;
-    preds += stride;
-    in += stride;
-    out += stride;
-  }
-
-  // Filter line-by-line.
-  while (row < last_row) {
-    // Leftmost pixel is predicted from above.
-    PredictLine(in, preds - stride, out, 1, inverse);
-    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
-    ++row;
-    preds += stride;
-    in += stride;
-    out += stride;
-  }
-}
-
-static void HorizontalFilter(const uint8_t* data, int width, int height,
-                             int stride, uint8_t* filtered_data) {
-  DoHorizontalFilter(data, width, height, stride, 0, height, 0, filtered_data);
-}
-
-static void HorizontalUnfilter(int width, int height, int stride, int row,
-                               int num_rows, uint8_t* data) {
-  DoHorizontalFilter(data, width, height, stride, row, num_rows, 1, data);
-}
-
-//------------------------------------------------------------------------------
-// Vertical filter.
-
-static WEBP_INLINE void DoVerticalFilter(const uint8_t* in,
-                                         int width, int height, int stride,
-                                         int row, int num_rows,
-                                         int inverse, uint8_t* out) {
-  const uint8_t* preds;
-  const size_t start_offset = row * stride;
-  const int last_row = row + num_rows;
-  SANITY_CHECK(in, out);
-  in += start_offset;
-  out += start_offset;
-  preds = inverse ? out : in;
-
-  if (row == 0) {
-    // Very first top-left pixel is copied.
-    out[0] = in[0];
-    // Rest of top scan-line is left-predicted.
-    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
-    row = 1;
-    in += stride;
-    out += stride;
-  } else {
-    // We are starting from in-between. Make sure 'preds' points to prev row.
-    preds -= stride;
-  }
-
-  // Filter line-by-line.
-  while (row < last_row) {
-    PredictLine(in, preds, out, width, inverse);
-    ++row;
-    preds += stride;
-    in += stride;
-    out += stride;
-  }
-}
-
-static void VerticalFilter(const uint8_t* data, int width, int height,
-                           int stride, uint8_t* filtered_data) {
-  DoVerticalFilter(data, width, height, stride, 0, height, 0, filtered_data);
-}
-
-static void VerticalUnfilter(int width, int height, int stride, int row,
-                             int num_rows, uint8_t* data) {
-  DoVerticalFilter(data, width, height, stride, row, num_rows, 1, data);
-}
-
-//------------------------------------------------------------------------------
-// Gradient filter.
-
-static WEBP_INLINE int GradientPredictor(uint8_t a, uint8_t b, uint8_t c) {
-  const int g = a + b - c;
-  return ((g & ~0xff) == 0) ? g : (g < 0) ? 0 : 255;  // clip to 8bit
-}
-
-static WEBP_INLINE void DoGradientFilter(const uint8_t* in,
-                                         int width, int height, int stride,
-                                         int row, int num_rows,
-                                         int inverse, uint8_t* out) {
-  const uint8_t* preds;
-  const size_t start_offset = row * stride;
-  const int last_row = row + num_rows;
-  SANITY_CHECK(in, out);
-  in += start_offset;
-  out += start_offset;
-  preds = inverse ? out : in;
-
-  // left prediction for top scan-line
-  if (row == 0) {
-    out[0] = in[0];
-    PredictLine(in + 1, preds, out + 1, width - 1, inverse);
-    row = 1;
-    preds += stride;
-    in += stride;
-    out += stride;
-  }
-
-  // Filter line-by-line.
-  while (row < last_row) {
-    int w;
-    // leftmost pixel: predict from above.
-    PredictLine(in, preds - stride, out, 1, inverse);
-    for (w = 1; w < width; ++w) {
-      const int pred = GradientPredictor(preds[w - 1],
-                                         preds[w - stride],
-                                         preds[w - stride - 1]);
-      out[w] = in[w] + (inverse ? pred : -pred);
-    }
-    ++row;
-    preds += stride;
-    in += stride;
-    out += stride;
-  }
-}
-
-static void GradientFilter(const uint8_t* data, int width, int height,
-                           int stride, uint8_t* filtered_data) {
-  DoGradientFilter(data, width, height, stride, 0, height, 0, filtered_data);
-}
-
-static void GradientUnfilter(int width, int height, int stride, int row,
-                             int num_rows, uint8_t* data) {
-  DoGradientFilter(data, width, height, stride, row, num_rows, 1, data);
-}
-
-#undef SANITY_CHECK
-
 // -----------------------------------------------------------------------------
 // Quick estimate of a potentially interesting filter mode to try.
 
 #define SMAX 16
 #define SDIFF(a, b) (abs((a) - (b)) >> 4)   // Scoring diff, in [0..SMAX)
 
-WEBP_FILTER_TYPE EstimateBestFilter(const uint8_t* data,
+static WEBP_INLINE int GradientPredictor(uint8_t a, uint8_t b, uint8_t c) {
+  const int g = a + b - c;
+  return ((g & ~0xff) == 0) ? g : (g < 0) ? 0 : 255;  // clip to 8bit
+}
+
+WEBP_FILTER_TYPE WebPEstimateBestFilter(const uint8_t* data,
                                         int width, int height, int stride) {
   int i, j;
   int bins[WEBP_FILTER_LAST][SMAX];
@@ -247,20 +74,3 @@ WEBP_FILTER_TYPE EstimateBestFilter(const uint8_t* data,
 #undef SDIFF
 
 //------------------------------------------------------------------------------
-
-WebPFilterFunc WebPFilters[WEBP_FILTER_LAST] = {
-  NULL,              // WEBP_FILTER_NONE
-  HorizontalFilter,  // WEBP_FILTER_HORIZONTAL
-  VerticalFilter,    // WEBP_FILTER_VERTICAL
-  GradientFilter     // WEBP_FILTER_GRADIENT
-};
-
-WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST] = {
-  NULL,                // WEBP_FILTER_NONE
-  HorizontalUnfilter,  // WEBP_FILTER_HORIZONTAL
-  VerticalUnfilter,    // WEBP_FILTER_VERTICAL
-  GradientUnfilter     // WEBP_FILTER_GRADIENT
-};
-
-//------------------------------------------------------------------------------
-

src/utils/filters.h

@@ -15,41 +15,14 @@
 #define WEBP_UTILS_FILTERS_H_
 
 #include "../webp/types.h"
+#include "../dsp/dsp.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-// Filters.
-typedef enum {
-  WEBP_FILTER_NONE = 0,
-  WEBP_FILTER_HORIZONTAL,
-  WEBP_FILTER_VERTICAL,
-  WEBP_FILTER_GRADIENT,
-  WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker
-  WEBP_FILTER_BEST,
-  WEBP_FILTER_FAST
-} WEBP_FILTER_TYPE;
-
-typedef void (*WebPFilterFunc)(const uint8_t* in, int width, int height,
-                               int stride, uint8_t* out);
-typedef void (*WebPUnfilterFunc)(int width, int height, int stride,
-                                 int row, int num_rows, uint8_t* data);
-
-// Filter the given data using the given predictor.
-// 'in' corresponds to a 2-dimensional pixel array of size (stride * height)
-// in raster order.
-// 'stride' is number of bytes per scan line (with possible padding).
-// 'out' should be pre-allocated.
-extern WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
-
-// In-place reconstruct the original data from the given filtered data.
-// The reconstruction will be done for 'num_rows' rows starting from 'row'
-// (assuming rows upto 'row - 1' are already reconstructed).
-extern WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
-
 // Fast estimate of a potentially good filter.
-WEBP_FILTER_TYPE EstimateBestFilter(const uint8_t* data,
+WEBP_FILTER_TYPE WebPEstimateBestFilter(const uint8_t* data,
                                         int width, int height, int stride);
 
 #ifdef __cplusplus