mirror of
https://github.com/webmproject/libwebp.git
synced 2024-11-19 20:08:28 +01:00
VP8EstimateQuality(): roughty estimate webp bitstream quality factor
This function returns a rough estimation of the quality factor used for compressing the WebP bitstream. Simple command line: 'webp_quality [-quiet] in.webp' should print the estimated quality factor. Change-Id: Ifba3e489461f5a587003ac9f08cc7556e9b24ac2
This commit is contained in:
skal
Pascal Massimino
parent
fee7b3d6ca
commit
e8ab6a825a
@ -5,15 +5,21 @@ noinst_HEADERS =
|
||||
noinst_HEADERS += ../src/webp/types.h
|
||||
|
||||
libwebpextras_la_SOURCES =
|
||||
libwebpextras_la_SOURCES += extras.c extras.h
|
||||
libwebpextras_la_SOURCES += extras.c extras.h quality_estimate.c
|
||||
|
||||
libwebpextras_la_CPPFLAGS = $(AM_CPPFLAGS)
|
||||
libwebpextras_la_LIBADD = ../src/libwebp.la
|
||||
|
||||
noinst_PROGRAMS = get_disto
|
||||
noinst_PROGRAMS = get_disto webp_quality
|
||||
|
||||
get_disto_SOURCES = get_disto.c
|
||||
get_disto_CPPFLAGS = $(AM_CPPFLAGS)
|
||||
get_disto_LDADD = ../imageio/libexample_util.la ../imageio/libimagedec.la
|
||||
get_disto_LDADD += ../src/libwebp.la
|
||||
get_disto_LDADD += $(PNG_LIBS) $(JPEG_LIBS) $(TIFF_LIBS)
|
||||
|
||||
webp_quality_SOURCES = webp_quality.c
|
||||
webp_quality_CPPFLAGS = $(AM_CPPFLAGS) $(USE_EXPERIMENTAL_CODE)
|
||||
webp_quality_LDADD = ../imageio/libexample_util.la ../imageio/libimagedec.la
|
||||
webp_quality_LDADD += ./libwebpextras.la
|
||||
webp_quality_LDADD += ../src/libwebp.la $(JPEG_LIBS) $(PNG_LIBS) $(TIFF_LIBS)
|
||||
|
||||
@ -44,6 +44,14 @@ WEBP_EXTERN(int) WebPImportRGB4444(const uint8_t* rgb4444, WebPPicture* pic);
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
|
||||
// Parse a bitstream, search for VP8 (lossy) header and report a
|
||||
// rough estimation of the quality factor used for compressing the bitstream.
|
||||
// Any error (invalid bitstream, lossless compression, incomplete header, etc.)
|
||||
// will return a value of -1.
|
||||
WEBP_EXTERN(int) VP8EstimateQuality(const uint8_t* const data, size_t size);
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
|
||||
#ifdef __cplusplus
|
||||
} // extern "C"
|
||||
#endif
|
||||
|
||||
121
extras/quality_estimate.c
Normal file
121
extras/quality_estimate.c
Normal file
@ -0,0 +1,121 @@
|
||||
// Copyright 2016 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.
|
||||
// -----------------------------------------------------------------------------
|
||||
//
|
||||
// VP8EstimateQuality(): rough encoding quality estimate
|
||||
//
|
||||
// Author: Skal (pascal.massimino@gmail.com)
|
||||
|
||||
#include "./extras.h"
|
||||
|
||||
#include <math.h>
|
||||
|
||||
//------------------------------------------------------------------------------
|
||||
|
||||
#define INVALID_BIT_POS (1ull << 63)
|
||||
|
||||
// In most cases, we don't need to use a full arithmetic decoder, since
|
||||
// all the header's bits are written using a uniform probability of 128.
|
||||
// We can just parse the header as if it was bits (works in 99.999% cases).
|
||||
static WEBP_INLINE uint32_t GetBit(const uint8_t* const data, size_t nb,
|
||||
uint64_t max_size, uint64_t* const bit_pos) {
|
||||
uint32_t val = 0;
|
||||
if (*bit_pos + nb <= 8 * max_size) {
|
||||
while (nb-- > 0) {
|
||||
const uint64_t p = (*bit_pos)++;
|
||||
const int bit = !!(data[p >> 3] & (128 >> ((p & 7))));
|
||||
val = (val << 1) | bit;
|
||||
}
|
||||
} else {
|
||||
*bit_pos = INVALID_BIT_POS;
|
||||
}
|
||||
return val;
|
||||
}
|
||||
|
||||
#define GET_BIT(n) GetBit(data, (n), size, &bit_pos)
|
||||
#define CONDITIONAL_SKIP(n) (GET_BIT(1) ? GET_BIT((n)) : 0)
|
||||
|
||||
int VP8EstimateQuality(const uint8_t* const data, size_t size) {
|
||||
size_t pos = 0;
|
||||
uint64_t bit_pos;
|
||||
uint64_t sig = 0x00;
|
||||
int ok = 0;
|
||||
int Q = -1;
|
||||
|
||||
if (data == NULL) return -1;
|
||||
|
||||
while (pos < size) {
|
||||
sig = (sig >> 8) | ((uint64_t)data[pos++] << 40);
|
||||
if ((sig >> 24) == 0x2a019dull) {
|
||||
ok = 1;
|
||||
break;
|
||||
}
|
||||
}
|
||||
if (!ok) return -1;
|
||||
if (pos + 4 > size) return -1;
|
||||
|
||||
// Skip main Header
|
||||
// width = (data[pos + 0] | (data[pos + 1] << 8)) & 0x3fff;
|
||||
// height = (data[pos + 2] | (data[pos + 3] << 8)) & 0x3fff;
|
||||
pos += 4;
|
||||
bit_pos = pos * 8;
|
||||
|
||||
GET_BIT(2); // color_space + clamp type
|
||||
|
||||
// Segment header
|
||||
if (GET_BIT(1)) { // use_segment_
|
||||
int s;
|
||||
const int update_map = GET_BIT(1);
|
||||
if (GET_BIT(1)) { // update data
|
||||
const int absolute_delta = GET_BIT(1);
|
||||
int q[4] = { 0, 0, 0, 0 };
|
||||
for (s = 0; s < 4; ++s) {
|
||||
if (GET_BIT(1)) {
|
||||
q[s] = GET_BIT(7);
|
||||
if (GET_BIT(1)) q[s] = -q[s]; // sign
|
||||
}
|
||||
}
|
||||
if (absolute_delta) Q = q[0]; // just use the first segment's quantizer
|
||||
for (s = 0; s < 4; ++s) CONDITIONAL_SKIP(7); // filter strength
|
||||
}
|
||||
if (update_map) {
|
||||
for (s = 0; s < 3; ++s) CONDITIONAL_SKIP(8);
|
||||
}
|
||||
}
|
||||
// Filter header
|
||||
GET_BIT(1 + 6 + 3); // simple + level + sharpness
|
||||
if (GET_BIT(1)) { // use_lf_delta
|
||||
if (GET_BIT(1)) { // update lf_delta?
|
||||
int n;
|
||||
for (n = 0; n < 4 + 4; ++n) CONDITIONAL_SKIP(6);
|
||||
}
|
||||
}
|
||||
// num partitions
|
||||
GET_BIT(2);
|
||||
|
||||
// ParseQuant
|
||||
{
|
||||
const int base_q = GET_BIT(7);
|
||||
/* dqy1_dc = */ CONDITIONAL_SKIP(5);
|
||||
/* dqy2_dc = */ CONDITIONAL_SKIP(5);
|
||||
/* dqy2_ac = */ CONDITIONAL_SKIP(5);
|
||||
/* dquv_dc = */ CONDITIONAL_SKIP(5);
|
||||
/* dquv_ac = */ CONDITIONAL_SKIP(5);
|
||||
|
||||
if (Q < 0) Q = base_q;
|
||||
}
|
||||
if (bit_pos == INVALID_BIT_POS) return -1;
|
||||
|
||||
// base mapping
|
||||
Q = (127 - Q) * 100 / 127;
|
||||
// correction for power-law behavior in low range
|
||||
if (Q < 80) {
|
||||
Q = (int)(pow(Q / 80., 1. / 0.38) * 80);
|
||||
}
|
||||
return Q;
|
||||
}
|
||||
49
extras/webp_quality.c
Normal file
49
extras/webp_quality.c
Normal file
@ -0,0 +1,49 @@
|
||||
// Simple tool to roughly evaluate the quality encoding of a webp bitstream
|
||||
//
|
||||
// Result is a *rough* estimation of the quality. You should just consider
|
||||
// the bucket it's in (q > 80? > 50? > 20?) and not take it for face value.
|
||||
/*
|
||||
gcc -o webp_quality webp_quality.c -O3 -I../ -L. -L../imageio \
|
||||
-lexample_util -limagedec -lwebpextras -lwebp -L/opt/local/lib \
|
||||
-lpng -lz -ljpeg -ltiff -lm -lpthread
|
||||
*/
|
||||
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
|
||||
#include "./extras.h"
|
||||
#include "../imageio/example_util.h"
|
||||
|
||||
int main(int argc, const char *argv[]) {
|
||||
int c;
|
||||
int quiet = 0;
|
||||
for (c = 1; c < argc; ++c) {
|
||||
if (!strcmp(argv[c], "-quiet")) {
|
||||
quiet = 1;
|
||||
} else if (!strcmp(argv[c], "-help") || !strcmp(argv[c], "-h")) {
|
||||
printf("webp_quality [-h][-quiet] webp_files...\n");
|
||||
return 1;
|
||||
} else {
|
||||
const char* const filename = argv[c];
|
||||
const uint8_t* data = NULL;
|
||||
size_t data_size = 0;
|
||||
int q;
|
||||
const int ok = ExUtilReadFile(filename, &data, &data_size);
|
||||
if (!ok) continue;
|
||||
q = VP8EstimateQuality(data, data_size);
|
||||
if (!quiet) printf("[%s] ", filename);
|
||||
if (q < 0) {
|
||||
fprintf(stderr, "Not a WebP file, or not a lossy WebP file.\n");
|
||||
} else {
|
||||
if (!quiet) {
|
||||
printf("Estimated quality factor: %d\n", q);
|
||||
} else {
|
||||
printf("%d\n", q); // just print the number
|
||||
}
|
||||
}
|
||||
free((void*)data);
|
||||
}
|
||||
}
|
||||
return 1;
|
||||
}
|
||||
@ -252,6 +252,7 @@ UTILS_ENC_OBJS = \
|
||||
|
||||
EXTRA_OBJS = \
|
||||
extras/extras.o \
|
||||
extras/quality_estimate.o \
|
||||
|
||||
LIBWEBPDECODER_OBJS = $(DEC_OBJS) $(DSP_DEC_OBJS) $(UTILS_DEC_OBJS)
|
||||
LIBWEBP_OBJS = $(LIBWEBPDECODER_OBJS) $(ENC_OBJS) $(DSP_ENC_OBJS) \
|
||||
@ -311,17 +312,18 @@ OUT_LIBS += src/libwebp.a
|
||||
EXTRA_LIB = extras/libwebpextras.a
|
||||
OUT_EXAMPLES = examples/cwebp examples/dwebp
|
||||
EXTRA_EXAMPLES = examples/gif2webp examples/vwebp examples/webpmux \
|
||||
examples/anim_diff extras/get_disto
|
||||
examples/anim_diff
|
||||
OTHER_EXAMPLES = extras/get_disto extras/webp_quality
|
||||
|
||||
OUTPUT = $(OUT_LIBS) $(OUT_EXAMPLES)
|
||||
ifeq ($(MAKECMDGOALS),clean)
|
||||
OUTPUT += $(EXTRA_EXAMPLES)
|
||||
OUTPUT += $(EXTRA_EXAMPLES) $(OTHER_EXAMPLES)
|
||||
OUTPUT += src/demux/libwebpdemux.a src/mux/libwebpmux.a $(EXTRA_LIB)
|
||||
OUTPUT += examples/libgifdec.a examples/libanim_util.a
|
||||
endif
|
||||
|
||||
ex: $(OUT_EXAMPLES)
|
||||
all: ex $(EXTRA_EXAMPLES)
|
||||
all: ex $(EXTRA_EXAMPLES) $(OTHER_EXAMPLES)
|
||||
extras: $(EXTRA_LIB)
|
||||
|
||||
$(EX_FORMAT_DEC_OBJS): %.o: %.h
|
||||
@ -379,11 +381,18 @@ examples/webpmux: imageio/libexample_util.a src/mux/libwebpmux.a
|
||||
examples/webpmux: src/libwebpdecoder.a
|
||||
|
||||
extras/get_disto: extras/get_disto.o
|
||||
extras/get_disto: imageio/libimagedec.a imageio/libexampledec.a
|
||||
extras/get_disto: imageio/libimagedec.a
|
||||
extras/get_disto: imageio/libexample_util.a
|
||||
extras/get_disto: src/libwebp.a $(CWEBP_LIBS)
|
||||
extras/get_disto: src/libwebp.a $(EXTRA_LIB)
|
||||
extras/get_disto: EXTRA_LIBS += $(CWEBP_LIBS)
|
||||
|
||||
$(OUT_EXAMPLES) $(EXTRA_EXAMPLES):
|
||||
extras/webp_quality: extras/webp_quality.o
|
||||
extras/webp_quality: imageio/libimagedec.a
|
||||
extras/webp_quality: imageio/libexample_util.a
|
||||
extras/webp_quality: src/libwebp.a $(EXTRA_LIB)
|
||||
extras/get_disto: EXTRA_LIBS += $(CWEBP_LIBS)
|
||||
|
||||
$(OUT_EXAMPLES) $(EXTRA_EXAMPLES) $(OTHER_EXAMPLES):
|
||||
$(CC) -o $@ $^ $(LDFLAGS)
|
||||
|
||||
dist: DESTDIR := dist
|
||||
|
||||
Loading…
Reference in New Issue
Block a user