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move the rescaling code into its own file and make enc/ and dec/ use it.

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(cherry picked from commit 8e92d9e380a89b7443a2e2c3d16ce5a222e8c1e8)

Conflicts:

	Android.mk
	makefile.unix
	src/dec/vp8l.c
	src/utils/Makefile.am
This commit is contained in:
Pascal Massimino
2012-03-22 10:30:20 +00:00
committed by James Zern
parent efc2016a31
commit 61c2d51fd7
10 changed files with 271 additions and 233 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
Android.mk
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@@ -39,6 +39,7 @@ LOCAL_SRC_FILES := \
src/utils/bit_writer.c \
src/utils/filters.c \
src/utils/quant_levels.c \
src/utils/rescaler.c \
src/utils/tcoder.c \
src/utils/thread.c \

1
Makefile.vc
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@@ -188,6 +188,7 @@ X_OBJS= \
$(DIROBJ)\utils\bit_writer.obj \
$(DIROBJ)\utils\filters.obj \
$(DIROBJ)\utils\quant_levels.obj \
$(DIROBJ)\utils\rescaler.obj \
$(DIROBJ)\utils\tcoder.obj \
$(DIROBJ)\utils\thread.obj \
$(X_OBJS) \

4
makefile.unix
View File

@@ -72,8 +72,8 @@ DSP_OBJS = src/dsp/cpu.o src/dsp/enc.o \
src/dsp/dec_neon.o src/dsp/upsampling.o src/dsp/upsampling_sse2.o \
src/dsp/yuv.o
UTILS_OBJS = src/utils/alpha.o src/utils/bit_reader.o src/utils/bit_writer.o \
src/utils/filters.o src/utils/quant_levels.o src/utils/thread.o \
src/utils/tcoder.o
src/utils/filters.o src/utils/quant_levels.o src/utils/rescaler.o \
src/utils/thread.o src/utils/tcoder.o
OBJS = $(DEC_OBJS) $(ENC_OBJS) $(DSP_OBJS) $(UTILS_OBJS)

52
src/dec/io.c
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@@ -234,14 +234,11 @@ static int EmitAlphaRGBA4444(const VP8Io* const io, WebPDecParams* const p) {
static int Rescale(const uint8_t* src, int src_stride,
int new_lines, WebPRescaler* const wrk) {
int num_lines_out = 0;
while (new_lines-- > 0) { // import new contribution of one source row.
WebPRescalerImportRow(src, 0, wrk);
src += src_stride;
wrk->y_accum -= wrk->y_sub;
while (wrk->y_accum <= 0) { // emit output row(s)
WebPRescalerExportRow(wrk);
++num_lines_out;
}
while (new_lines > 0) { // import new contributions of source rows.
const int lines_in = WebPRescalerImport(wrk, new_lines, src, src_stride);
src += lines_in * src_stride;
new_lines -= lines_in;
num_lines_out += WebPRescalerExport(wrk); // emit output row(s)
}
return num_lines_out;
}
@@ -318,20 +315,6 @@ static int InitYUVRescaler(const VP8Io* const io, WebPDecParams* const p) {
//------------------------------------------------------------------------------
// RGBA rescaling
// import new contributions until one row is ready to be output, or all input
// is consumed.
static int Import(const uint8_t* src, int src_stride,
int new_lines, WebPRescaler* const wrk) {
int num_lines_in = 0;
while (num_lines_in < new_lines && wrk->y_accum > 0) {
WebPRescalerImportRow(src, 0, wrk);
src += src_stride;
++num_lines_in;
wrk->y_accum -= wrk->y_sub;
}
return num_lines_in;
}
static int ExportRGB(WebPDecParams* const p, int y_pos) {
const WebPYUV444Converter convert =
WebPYUV444Converters[p->output->colorspace];
@@ -340,7 +323,8 @@ static int ExportRGB(WebPDecParams* const p, int y_pos) {
int num_lines_out = 0;
// For RGB rescaling, because of the YUV420, current scan position
// U/V can be +1/-1 line from the Y one. Hence the double test.
while (p->scaler_y.y_accum <= 0 && p->scaler_u.y_accum <= 0) {
while (WebPRescalerHasPendingOutput(&p->scaler_y) &&
WebPRescalerHasPendingOutput(&p->scaler_u)) {
assert(p->last_y + y_pos + num_lines_out < p->output->height);
assert(p->scaler_u.y_accum == p->scaler_v.y_accum);
WebPRescalerExportRow(&p->scaler_y);
@@ -360,12 +344,15 @@ static int EmitRescaledRGB(const VP8Io* const io, WebPDecParams* const p) {
int j = 0, uv_j = 0;
int num_lines_out = 0;
while (j < mb_h) {
const int y_lines_in = Import(io->y + j * io->y_stride, io->y_stride,
mb_h - j, &p->scaler_y);
const int u_lines_in = Import(io->u + uv_j * io->uv_stride, io->uv_stride,
uv_mb_h - uv_j, &p->scaler_u);
const int v_lines_in = Import(io->v + uv_j * io->uv_stride, io->uv_stride,
uv_mb_h - uv_j, &p->scaler_v);
const int y_lines_in =
WebPRescalerImport(&p->scaler_y, mb_h - j,
io->y + j * io->y_stride, io->y_stride);
const int u_lines_in =
WebPRescalerImport(&p->scaler_u, uv_mb_h - uv_j,
io->u + uv_j * io->uv_stride, io->uv_stride);
const int v_lines_in =
WebPRescalerImport(&p->scaler_v, uv_mb_h - uv_j,
io->v + uv_j * io->uv_stride, io->uv_stride);
(void)v_lines_in; // remove a gcc warning
assert(u_lines_in == v_lines_in);
j += y_lines_in;
@@ -380,7 +367,7 @@ static int ExportAlpha(WebPDecParams* const p, int y_pos) {
uint8_t* dst = buf->rgba + (p->last_y + y_pos) * buf->stride +
(p->output->colorspace == MODE_ARGB ? 0 : 3);
int num_lines_out = 0;
while (p->scaler_a.y_accum <= 0) {
while (WebPRescalerHasPendingOutput(&p->scaler_a)) {
int i;
assert(p->last_y + y_pos + num_lines_out < p->output->height);
WebPRescalerExportRow(&p->scaler_a);
@@ -397,7 +384,7 @@ static int ExportAlphaRGBA4444(WebPDecParams* const p, int y_pos) {
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* dst = buf->rgba + (p->last_y + y_pos) * buf->stride + 1;
int num_lines_out = 0;
while (p->scaler_a.y_accum <= 0) {
while (WebPRescalerHasPendingOutput(&p->scaler_a)) {
int i;
assert(p->last_y + y_pos + num_lines_out < p->output->height);
WebPRescalerExportRow(&p->scaler_a);
@@ -420,7 +407,8 @@ static int EmitRescaledAlphaRGB(const VP8Io* const io, WebPDecParams* const p) {
WebPRescaler* const scaler = &p->scaler_a;
int j = 0, pos = 0;
while (j < io->mb_h) {
j += Import(io->a + j * io->width, io->width, io->mb_h - j, scaler);
j += WebPRescalerImport(scaler, io->mb_h - j,
io->a + j * io->width, io->width);
pos += output_func(p, pos);
}
}

93
src/dec/webp.c
View File

@@ -610,7 +610,7 @@ VP8StatusCode WebPDecode(const uint8_t* data, uint32_t data_size,
}
//------------------------------------------------------------------------------
// Cropping & rescaling.
// Cropping and rescaling.
int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
VP8Io* const io) {
@@ -664,97 +664,6 @@ int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
return 1;
}
#define RFIX 30
#define MULT_FIX(x,y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX)
void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
uint8_t* const dst, int dst_width, int dst_height,
int dst_stride, int num_channels, int x_add, int x_sub,
int y_add, int y_sub, int32_t* const work) {
wrk->x_expand = (src_width < dst_width);
wrk->src_width = src_width;
wrk->src_height = src_height;
wrk->dst_width = dst_width;
wrk->dst_height = dst_height;
wrk->dst = dst;
wrk->dst_stride = dst_stride;
wrk->num_channels = num_channels;
// for 'x_expand', we use bilinear interpolation
wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add - x_sub;
wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub;
wrk->y_accum = y_add;
wrk->y_add = y_add;
wrk->y_sub = y_sub;
wrk->fx_scale = (1 << RFIX) / x_sub;
wrk->fy_scale = (1 << RFIX) / y_sub;
wrk->fxy_scale = wrk->x_expand ?
((int64_t)dst_height << RFIX) / (x_sub * src_height) :
((int64_t)dst_height << RFIX) / (x_add * src_height);
wrk->irow = work;
wrk->frow = work + num_channels * dst_width;
}
void WebPRescalerImportRow(const uint8_t* const src, int channel,
WebPRescaler* const wrk) {
const int x_stride = wrk->num_channels;
const int x_out_max = wrk->dst_width * wrk->num_channels;
int x_in = channel;
int x_out;
int accum = 0;
if (!wrk->x_expand) {
int sum = 0;
for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
accum += wrk->x_add;
for (; accum > 0; accum -= wrk->x_sub) {
sum += src[x_in];
x_in += x_stride;
}
{ // Emit next horizontal pixel.
const int32_t base = src[x_in];
const int32_t frac = base * (-accum);
x_in += x_stride;
wrk->frow[x_out] = (sum + base) * wrk->x_sub - frac;
// fresh fractional start for next pixel
sum = (int)MULT_FIX(frac, wrk->fx_scale);
}
}
} else { // simple bilinear interpolation
int left = src[channel], right = src[channel];
for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
if (accum < 0) {
left = right;
x_in += x_stride;
right = src[x_in];
accum += wrk->x_add;
}
wrk->frow[x_out] = right * wrk->x_add + (left - right) * accum;
accum -= wrk->x_sub;
}
}
// Accumulate the new row's contribution
for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
wrk->irow[x_out] += wrk->frow[x_out];
}
}
void WebPRescalerExportRow(WebPRescaler* const wrk) {
int x_out;
const int yscale = wrk->fy_scale * (-wrk->y_accum);
const int x_out_max = wrk->dst_width * wrk->num_channels;
assert(wrk->y_accum <= 0);
for (x_out = 0; x_out < x_out_max; ++x_out) {
const int frac = (int)MULT_FIX(wrk->frow[x_out], yscale);
const int v = (int)MULT_FIX(wrk->irow[x_out] - frac, wrk->fxy_scale);
wrk->dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
wrk->irow[x_out] = frac; // new fractional start
}
wrk->y_accum += wrk->y_add;
wrk->dst += wrk->dst_stride;
}
#undef MULT_FIX
#undef RFIX
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)

32
src/dec/webpi.h
View File

@@ -17,6 +17,7 @@ extern "C" {
#endif
#include "../webp/decode_vp8.h"
#include "../utils/rescaler.h"
//------------------------------------------------------------------------------
// WebPDecParams: Decoding output parameters. Transient internal object.
@@ -24,23 +25,6 @@ extern "C" {
typedef struct WebPDecParams WebPDecParams;
typedef int (*OutputFunc)(const VP8Io* const io, WebPDecParams* const p);
// Structure use for on-the-fly rescaling
typedef struct {
int x_expand; // true if we're expanding in the x direction
int num_channels; // bytes to jump between pixels
int fy_scale, fx_scale; // fixed-point scaling factor
int64_t fxy_scale; // ''
// we need hpel-precise add/sub increments, for the downsampled U/V planes.
int y_accum; // vertical accumulator
int y_add, y_sub; // vertical increments (add ~= src, sub ~= dst)
int x_add, x_sub; // horizontal increments (add ~= src, sub ~= dst)
int src_width, src_height; // source dimensions
int dst_width, dst_height; // destination dimensions
uint8_t* dst;
int dst_stride;
int32_t* irow, *frow; // work buffer
} WebPRescaler;
struct WebPDecParams {
WebPDecBuffer* output; // output buffer.
uint8_t* tmp_y, *tmp_u, *tmp_v; // cache for the fancy upsampler
@@ -167,20 +151,6 @@ void WebPGrabDecBuffer(WebPDecBuffer* const src, WebPDecBuffer* const dst);
int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
VP8Io* const io);
// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
uint8_t* const dst, int dst_width, int dst_height,
int dst_stride, int num_channels, int x_add, int x_sub,
int y_add, int y_sub, int32_t* const work);
// Import a row of data and save its contribution in the rescaler.
// 'channel' denotes the channel number to be imported.
void WebPRescalerImportRow(const uint8_t* const src, int channel,
WebPRescaler* const wrk);
// Export a row from rescaler.
void WebPRescalerExportRow(WebPRescaler* const wrk);
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)

91
src/enc/picture.c
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@@ -14,6 +14,7 @@
#include <math.h>
#include "./vp8enci.h"
#include "../utils/rescaler.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
@@ -224,89 +225,29 @@ int WebPPictureCrop(WebPPicture* const pic,
//------------------------------------------------------------------------------
// Simple picture rescaler
#define RFIX 30
#define MULT(x,y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX)
static WEBP_INLINE void ImportRow(const uint8_t* src, int src_width,
int32_t* frow, int32_t* irow, int dst_width) {
const int x_expand = (src_width < dst_width);
const int fx_scale = (1 << RFIX) / dst_width;
int x_in = 0;
int x_out;
int x_accum = 0;
if (!x_expand) {
int sum = 0;
for (x_out = 0; x_out < dst_width; ++x_out) {
x_accum += src_width - dst_width;
for (; x_accum > 0; x_accum -= dst_width) {
sum += src[x_in++];
}
{ // Emit next horizontal pixel.
const int32_t base = src[x_in++];
const int32_t frac = base * (-x_accum);
frow[x_out] = (sum + base) * dst_width - frac;
sum = MULT(frac, fx_scale); // fresh fractional start for next pixel
}
}
} else { // simple bilinear interpolation
int left = src[0], right = src[0];
for (x_out = 0; x_out < dst_width; ++x_out) {
if (x_accum < 0) {
left = right;
right = src[++x_in];
x_accum += dst_width - 1;
}
frow[x_out] = right * (dst_width - 1) + (left - right) * x_accum;
x_accum -= src_width - 1;
}
}
// Accumulate the new row's contribution
for (x_out = 0; x_out < dst_width; ++x_out) {
irow[x_out] += frow[x_out];
}
}
static void ExportRow(int32_t* frow, int32_t* irow, uint8_t* dst, int dst_width,
const int yscale, const int64_t fxy_scale) {
int x_out;
for (x_out = 0; x_out < dst_width; ++x_out) {
const int frac = MULT(frow[x_out], yscale);
const int v = (int)(MULT(irow[x_out] - frac, fxy_scale));
dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
irow[x_out] = frac; // new fractional start
}
}
static void RescalePlane(const uint8_t* src,
int src_width, int src_height, int src_stride,
uint8_t* dst,
int dst_width, int dst_height, int dst_stride,
int32_t* const work) {
const int x_expand = (src_width < dst_width);
const int fy_scale = (1 << RFIX) / dst_height;
const int64_t fxy_scale = x_expand ?
((int64_t)dst_height << RFIX) / (dst_width * src_height) :
((int64_t)dst_height << RFIX) / (src_width * src_height);
int y_accum = src_height;
int y;
int32_t* irow = work; // integral contribution
int32_t* frow = work + dst_width; // fractional contribution
WebPRescaler rescaler;
int y = 0;
WebPRescalerInit(&rescaler, src_width, src_height,
dst, dst_width, dst_height, dst_stride,
1,
src_width, dst_width,
src_height, dst_height,
work);
memset(work, 0, 2 * dst_width * sizeof(*work));
for (y = 0; y < src_height; ++y) {
// import new contribution of one source row.
ImportRow(src, src_width, frow, irow, dst_width);
src += src_stride;
// emit output row(s)
y_accum -= dst_height;
for (; y_accum <= 0; y_accum += src_height) {
const int yscale = fy_scale * (-y_accum);
ExportRow(frow, irow, dst, dst_width, yscale, fxy_scale);
dst += dst_stride;
}
while (y < src_height) {
const int num_lines_in =
WebPRescalerImport(&rescaler, src_height - y, src, src_stride);
y += num_lines_in;
src += num_lines_in * src_stride;
WebPRescalerExport(&rescaler);
}
}
#undef MULT
#undef RFIX
int WebPPictureRescale(WebPPicture* const pic, int width, int height) {
WebPPicture tmp;
@@ -332,7 +273,7 @@ int WebPPictureRescale(WebPPicture* const pic, int width, int height) {
tmp.height = height;
if (!WebPPictureAlloc(&tmp)) return 0;
work = (int32_t*)malloc(2 * width * sizeof(int32_t));
work = (int32_t*)malloc(2 * width * sizeof(*work));
if (work == NULL) {
WebPPictureFree(&tmp);
return 0;

2
src/utils/Makefile.am
View File

@@ -4,7 +4,7 @@ libwebputils_la_SOURCES = alpha.h alpha.c \
bit_reader.h bit_reader.c \
bit_writer.h bit_writer.c \
filters.h filters.c \
quant_levels.c \
quant_levels.c rescaler.c \
tcoder.h tcoderi.h tcoder.c \
thread.h thread.c
libwebputilsinclude_HEADERS = ../webp/types.h

152
src/utils/rescaler.c Normal file
View File

@@ -0,0 +1,152 @@
// Copyright 2012 Google Inc. All Rights Reserved.
//
// This code is licensed under the same terms as WebM:
// Software License Agreement: http://www.webmproject.org/license/software/
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// Rescaling functions
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include "./rescaler.h"
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define RFIX 30
#define MULT_FIX(x,y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX)
void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
uint8_t* const dst, int dst_width, int dst_height,
int dst_stride, int num_channels, int x_add, int x_sub,
int y_add, int y_sub, int32_t* const work) {
wrk->x_expand = (src_width < dst_width);
wrk->src_width = src_width;
wrk->src_height = src_height;
wrk->dst_width = dst_width;
wrk->dst_height = dst_height;
wrk->dst = dst;
wrk->dst_stride = dst_stride;
wrk->num_channels = num_channels;
// for 'x_expand', we use bilinear interpolation
wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add - x_sub;
wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub;
wrk->y_accum = y_add;
wrk->y_add = y_add;
wrk->y_sub = y_sub;
wrk->fx_scale = (1 << RFIX) / x_sub;
wrk->fy_scale = (1 << RFIX) / y_sub;
wrk->fxy_scale = wrk->x_expand ?
((int64_t)dst_height << RFIX) / (x_sub * src_height) :
((int64_t)dst_height << RFIX) / (x_add * src_height);
wrk->irow = work;
wrk->frow = work + num_channels * dst_width;
}
void WebPRescalerImportRow(WebPRescaler* const wrk,
const uint8_t* const src, int channel) {
const int x_stride = wrk->num_channels;
const int x_out_max = wrk->dst_width * wrk->num_channels;
int x_in = channel;
int x_out;
int accum = 0;
if (!wrk->x_expand) {
int sum = 0;
for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
accum += wrk->x_add;
for (; accum > 0; accum -= wrk->x_sub) {
sum += src[x_in];
x_in += x_stride;
}
{ // Emit next horizontal pixel.
const int32_t base = src[x_in];
const int32_t frac = base * (-accum);
x_in += x_stride;
wrk->frow[x_out] = (sum + base) * wrk->x_sub - frac;
// fresh fractional start for next pixel
sum = (int)MULT_FIX(frac, wrk->fx_scale);
}
}
} else { // simple bilinear interpolation
int left = src[channel], right = src[channel];
for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
if (accum < 0) {
left = right;
x_in += x_stride;
right = src[x_in];
accum += wrk->x_add;
}
wrk->frow[x_out] = right * wrk->x_add + (left - right) * accum;
accum -= wrk->x_sub;
}
}
// Accumulate the new row's contribution
for (x_out = channel; x_out < x_out_max; x_out += x_stride) {
wrk->irow[x_out] += wrk->frow[x_out];
}
}
uint8_t* WebPRescalerExportRow(WebPRescaler* const wrk) {
if (wrk->y_accum <= 0) {
int x_out;
uint8_t* const dst = wrk->dst;
int32_t* const irow = wrk->irow;
const int32_t* const frow = wrk->frow;
const int yscale = wrk->fy_scale * (-wrk->y_accum);
const int x_out_max = wrk->dst_width * wrk->num_channels;
for (x_out = 0; x_out < x_out_max; ++x_out) {
const int frac = (int)MULT_FIX(frow[x_out], yscale);
const int v = (int)MULT_FIX(irow[x_out] - frac, wrk->fxy_scale);
dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
irow[x_out] = frac; // new fractional start
}
wrk->y_accum += wrk->y_add;
wrk->dst += wrk->dst_stride;
return dst;
} else {
return NULL;
}
}
#undef MULT_FIX
#undef RFIX
//------------------------------------------------------------------------------
// all-in-one calls
int WebPRescalerImport(WebPRescaler* const wrk, int num_lines,
const uint8_t* src, int src_stride) {
int total_imported = 0;
while (total_imported < num_lines && wrk->y_accum > 0) {
int channel;
for (channel = 0; channel < wrk->num_channels; ++channel) {
WebPRescalerImportRow(wrk, src, channel);
}
src += src_stride;
++total_imported;
wrk->y_accum -= wrk->y_sub;
}
return total_imported;
}
int WebPRescalerExport(WebPRescaler* const rescaler) {
int total_exported = 0;
while (WebPRescalerHasPendingOutput(rescaler)) {
WebPRescalerExportRow(rescaler);
++total_exported;
}
return total_exported;
}
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif

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src/utils/rescaler.h Normal file
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// Copyright 2012 Google Inc. All Rights Reserved.
//
// This code is licensed under the same terms as WebM:
// Software License Agreement: http://www.webmproject.org/license/software/
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// Rescaling functions
//
// Author: skal@google.com (Pascal Massimino)
#ifndef WEBP_UTILS_RESCALER_H_
#define WEBP_UTILS_RESCALER_H_
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#include "../webp/types.h"
// Structure used for on-the-fly rescaling
typedef struct {
int x_expand; // true if we're expanding in the x direction
int num_channels; // bytes to jump between pixels
int fy_scale, fx_scale; // fixed-point scaling factor
int64_t fxy_scale; // ''
// we need hpel-precise add/sub increments, for the downsampled U/V planes.
int y_accum; // vertical accumulator
int y_add, y_sub; // vertical increments (add ~= src, sub ~= dst)
int x_add, x_sub; // horizontal increments (add ~= src, sub ~= dst)
int src_width, src_height; // source dimensions
int dst_width, dst_height; // destination dimensions
uint8_t* dst;
int dst_stride;
int32_t* irow, *frow; // work buffer
} WebPRescaler;
// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
uint8_t* const dst,
int dst_width, int dst_height, int dst_stride,
int num_channels,
int x_add, int x_sub,
int y_add, int y_sub,
int32_t* const work);
// Import a row of data and save its contribution in the rescaler.
// 'channel' denotes the channel number to be imported.
void WebPRescalerImportRow(WebPRescaler* const rescaler,
const uint8_t* const src, int channel);
// Import multiple rows over all channels, until at least one row is ready to
// be exported. Returns the actual number of lines that were imported.
int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows,
const uint8_t* src, int src_stride);
// Return true if there is pending output rows ready.
static WEBP_INLINE
int WebPRescalerHasPendingOutput(const WebPRescaler* const rescaler) {
return (rescaler->y_accum <= 0);
}
// Export one row from rescaler. Returns the pointer where output was written,
// or NULL if no row was pending.
uint8_t* WebPRescalerExportRow(WebPRescaler* const wrk);
// Export as many rows as possible. Return the numbers of rows written.
int WebPRescalerExport(WebPRescaler* const wrk);
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif
#endif /* WEBP_UTILS_RESCALER_H_ */