241 lines
7.9 KiB
C
241 lines
7.9 KiB
C
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// Copyright 2011 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Spatial prediction using various filters
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//
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// Author: Urvang (urvang@google.com)
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#include "./dsp.h"
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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//------------------------------------------------------------------------------
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// Helpful macro.
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# define SANITY_CHECK(in, out) \
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assert(in != NULL); \
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assert(out != NULL); \
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assert(width > 0); \
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assert(height > 0); \
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assert(stride >= width); \
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assert(row >= 0 && num_rows > 0 && row + num_rows <= height); \
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(void)height; // Silence unused warning.
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static WEBP_INLINE void PredictLine(const uint8_t* src, const uint8_t* pred,
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uint8_t* dst, int length, int inverse) {
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int i;
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if (inverse) {
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for (i = 0; i < length; ++i) dst[i] = src[i] + pred[i];
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} else {
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for (i = 0; i < length; ++i) dst[i] = src[i] - pred[i];
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}
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}
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//------------------------------------------------------------------------------
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// Horizontal filter.
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static WEBP_INLINE void DoHorizontalFilter(const uint8_t* in,
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int width, int height, int stride,
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int row, int num_rows,
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int inverse, uint8_t* out) {
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const uint8_t* preds;
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const size_t start_offset = row * stride;
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const int last_row = row + num_rows;
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SANITY_CHECK(in, out);
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in += start_offset;
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out += start_offset;
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preds = inverse ? out : in;
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if (row == 0) {
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// Leftmost pixel is the same as input for topmost scanline.
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out[0] = in[0];
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PredictLine(in + 1, preds, out + 1, width - 1, inverse);
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row = 1;
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preds += stride;
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in += stride;
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out += stride;
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}
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// Filter line-by-line.
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while (row < last_row) {
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// Leftmost pixel is predicted from above.
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PredictLine(in, preds - stride, out, 1, inverse);
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PredictLine(in + 1, preds, out + 1, width - 1, inverse);
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++row;
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preds += stride;
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in += stride;
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out += stride;
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}
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}
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//------------------------------------------------------------------------------
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// Vertical filter.
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static WEBP_INLINE void DoVerticalFilter(const uint8_t* in,
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int width, int height, int stride,
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int row, int num_rows,
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int inverse, uint8_t* out) {
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const uint8_t* preds;
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const size_t start_offset = row * stride;
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const int last_row = row + num_rows;
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SANITY_CHECK(in, out);
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in += start_offset;
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out += start_offset;
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preds = inverse ? out : in;
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if (row == 0) {
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// Very first top-left pixel is copied.
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out[0] = in[0];
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// Rest of top scan-line is left-predicted.
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PredictLine(in + 1, preds, out + 1, width - 1, inverse);
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row = 1;
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in += stride;
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out += stride;
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} else {
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// We are starting from in-between. Make sure 'preds' points to prev row.
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preds -= stride;
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}
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// Filter line-by-line.
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while (row < last_row) {
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PredictLine(in, preds, out, width, inverse);
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++row;
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preds += stride;
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in += stride;
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out += stride;
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}
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}
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//------------------------------------------------------------------------------
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// Gradient filter.
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static WEBP_INLINE int GradientPredictor(uint8_t a, uint8_t b, uint8_t c) {
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const int g = a + b - c;
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return ((g & ~0xff) == 0) ? g : (g < 0) ? 0 : 255; // clip to 8bit
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}
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static WEBP_INLINE void DoGradientFilter(const uint8_t* in,
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int width, int height, int stride,
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int row, int num_rows,
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int inverse, uint8_t* out) {
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const uint8_t* preds;
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const size_t start_offset = row * stride;
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const int last_row = row + num_rows;
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SANITY_CHECK(in, out);
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in += start_offset;
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out += start_offset;
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preds = inverse ? out : in;
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// left prediction for top scan-line
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if (row == 0) {
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out[0] = in[0];
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PredictLine(in + 1, preds, out + 1, width - 1, inverse);
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row = 1;
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preds += stride;
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in += stride;
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out += stride;
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}
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// Filter line-by-line.
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while (row < last_row) {
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int w;
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// leftmost pixel: predict from above.
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PredictLine(in, preds - stride, out, 1, inverse);
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for (w = 1; w < width; ++w) {
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const int pred = GradientPredictor(preds[w - 1],
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preds[w - stride],
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preds[w - stride - 1]);
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out[w] = in[w] + (inverse ? pred : -pred);
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}
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++row;
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preds += stride;
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in += stride;
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out += stride;
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}
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}
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#undef SANITY_CHECK
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//------------------------------------------------------------------------------
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static void HorizontalFilter(const uint8_t* data, int width, int height,
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int stride, uint8_t* filtered_data) {
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DoHorizontalFilter(data, width, height, stride, 0, height, 0, filtered_data);
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}
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static void VerticalFilter(const uint8_t* data, int width, int height,
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int stride, uint8_t* filtered_data) {
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DoVerticalFilter(data, width, height, stride, 0, height, 0, filtered_data);
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}
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static void GradientFilter(const uint8_t* data, int width, int height,
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int stride, uint8_t* filtered_data) {
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DoGradientFilter(data, width, height, stride, 0, height, 0, filtered_data);
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}
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//------------------------------------------------------------------------------
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static void VerticalUnfilter(int width, int height, int stride, int row,
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int num_rows, uint8_t* data) {
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DoVerticalFilter(data, width, height, stride, row, num_rows, 1, data);
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}
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static void HorizontalUnfilter(int width, int height, int stride, int row,
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int num_rows, uint8_t* data) {
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DoHorizontalFilter(data, width, height, stride, row, num_rows, 1, data);
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}
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static void GradientUnfilter(int width, int height, int stride, int row,
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int num_rows, uint8_t* data) {
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DoGradientFilter(data, width, height, stride, row, num_rows, 1, data);
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}
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//------------------------------------------------------------------------------
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// Init function
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WebPFilterFunc WebPFilters[WEBP_FILTER_LAST];
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WebPUnfilterFunc WebPUnfilters[WEBP_FILTER_LAST];
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extern void VP8FiltersInitMIPSdspR2(void);
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extern void VP8FiltersInitSSE2(void);
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static volatile VP8CPUInfo filters_last_cpuinfo_used =
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(VP8CPUInfo)&filters_last_cpuinfo_used;
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WEBP_TSAN_IGNORE_FUNCTION void VP8FiltersInit(void) {
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if (filters_last_cpuinfo_used == VP8GetCPUInfo) return;
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WebPUnfilters[WEBP_FILTER_NONE] = NULL;
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WebPUnfilters[WEBP_FILTER_HORIZONTAL] = HorizontalUnfilter;
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WebPUnfilters[WEBP_FILTER_VERTICAL] = VerticalUnfilter;
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WebPUnfilters[WEBP_FILTER_GRADIENT] = GradientUnfilter;
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WebPFilters[WEBP_FILTER_NONE] = NULL;
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WebPFilters[WEBP_FILTER_HORIZONTAL] = HorizontalFilter;
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WebPFilters[WEBP_FILTER_VERTICAL] = VerticalFilter;
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WebPFilters[WEBP_FILTER_GRADIENT] = GradientFilter;
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if (VP8GetCPUInfo != NULL) {
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#if defined(WEBP_USE_SSE2)
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if (VP8GetCPUInfo(kSSE2)) {
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VP8FiltersInitSSE2();
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}
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#endif
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#if defined(WEBP_USE_MIPS_DSP_R2)
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if (VP8GetCPUInfo(kMIPSdspR2)) {
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VP8FiltersInitMIPSdspR2();
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}
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#endif
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}
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filters_last_cpuinfo_used = VP8GetCPUInfo;
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}
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