// Copyright 2015 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.
// -----------------------------------------------------------------------------
//
// Checks if given pair of animated GIF/WebP images are identical:
// That is: their reconstructed canvases match pixel-by-pixel and their other
// animation properties (loop count etc) also match.
//
// example: anim_diff foo.gif bar.webp
#include <assert.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h> // for 'strtod'.
#include <string.h> // for 'strcmp'.
#include "./anim_util.h"
#if defined(_MSC_VER) && _MSC_VER < 1900
#define snprintf _snprintf
#endif
// Returns true if 'a + b' will overflow.
static int AdditionWillOverflow(int a, int b) {
return (b > 0) && (a > INT_MAX - b);
}
static int FramesAreEqual(const uint8_t* const rgba1,
const uint8_t* const rgba2, int width, int height) {
const int stride = width * 4; // Always true for 'DecodedFrame.rgba'.
return !memcmp(rgba1, rgba2, stride * height);
}
static WEBP_INLINE int PixelsAreSimilar(uint32_t src, uint32_t dst,
int max_allowed_diff) {
const int src_a = (src >> 24) & 0xff;
const int src_r = (src >> 16) & 0xff;
const int src_g = (src >> 8) & 0xff;
const int src_b = (src >> 0) & 0xff;
const int dst_a = (dst >> 24) & 0xff;
const int dst_r = (dst >> 16) & 0xff;
const int dst_g = (dst >> 8) & 0xff;
const int dst_b = (dst >> 0) & 0xff;
return (abs(src_r * src_a - dst_r * dst_a) <= (max_allowed_diff * 255)) &&
(abs(src_g * src_a - dst_g * dst_a) <= (max_allowed_diff * 255)) &&
(abs(src_b * src_a - dst_b * dst_a) <= (max_allowed_diff * 255)) &&
(abs(src_a - dst_a) <= max_allowed_diff);
}
static int FramesAreSimilar(const uint8_t* const rgba1,
const uint8_t* const rgba2,
int width, int height, int max_allowed_diff) {
int i, j;
assert(max_allowed_diff > 0);
for (j = 0; j < height; ++j) {
for (i = 0; i < width; ++i) {
const int stride = width * 4;
const size_t offset = j * stride + i;
if (!PixelsAreSimilar(rgba1[offset], rgba2[offset], max_allowed_diff)) {
return 0;
}
}
}
return 1;
}
// Minimize number of frames by combining successive frames that have at max
// 'max_diff' difference per channel between corresponding pixels.
static void MinimizeAnimationFrames(AnimatedImage* const img, int max_diff) {
uint32_t i;
for (i = 1; i < img->num_frames; ++i) {
DecodedFrame* const frame1 = &img->frames[i - 1];
DecodedFrame* const frame2 = &img->frames[i];
const uint8_t* const rgba1 = frame1->rgba;
const uint8_t* const rgba2 = frame2->rgba;
int should_merge_frames = 0;
// If merging frames will result in integer overflow for 'duration',
// skip merging.
if (AdditionWillOverflow(frame1->duration, frame2->duration)) continue;
if (max_diff > 0) {
should_merge_frames = FramesAreSimilar(rgba1, rgba2, img->canvas_width,
img->canvas_height, max_diff);
} else {
should_merge_frames =
FramesAreEqual(rgba1, rgba2, img->canvas_width, img->canvas_height);
}
if (should_merge_frames) { // Merge 'i+1'th frame into 'i'th frame.
frame1->duration += frame2->duration;
if (i + 1 < img->num_frames) {
memmove(&img->frames[i], &img->frames[i + 1],
(img->num_frames - i - 1) * sizeof(*img->frames));
}
--img->num_frames;
--i;
}
}
}
static int CompareValues(uint32_t a, uint32_t b, const char* output_str) {
if (a != b) {
fprintf(stderr, "%s: %d vs %d\n", output_str, a, b);
return 0;
}
return 1;
}
static int CompareBackgroundColor(uint32_t bg1, uint32_t bg2, int premultiply) {
if (premultiply) {
const int alpha1 = (bg1 >> 24) & 0xff;
const int alpha2 = (bg2 >> 24) & 0xff;
if (alpha1 == 0 && alpha2 == 0) return 1;
}
if (bg1 != bg2) {
fprintf(stderr, "Background color mismatch: 0x%08x vs 0x%08x\n",
bg1, bg2);
return 0;
}
return 1;
}
// Note: As long as frame durations and reconstructed frames are identical, it
// is OK for other aspects like offsets, dispose/blend method to vary.
static int CompareAnimatedImagePair(const AnimatedImage* const img1,
const AnimatedImage* const img2,
int premultiply,
double min_psnr) {
int ok = 1;
const int is_multi_frame_image = (img1->num_frames > 1);
uint32_t i;
ok = CompareValues(img1->canvas_width, img2->canvas_width,
"Canvas width mismatch") && ok;
ok = CompareValues(img1->canvas_height, img2->canvas_height,
"Canvas height mismatch") && ok;
ok = CompareValues(img1->num_frames, img2->num_frames,
"Frame count mismatch") && ok;
if (!ok) return 0; // These are fatal failures, can't proceed.
if (is_multi_frame_image) { // Checks relevant for multi-frame images only.
ok = CompareValues(img1->loop_count, img2->loop_count,
"Loop count mismatch") && ok;
ok = CompareBackgroundColor(img1->bgcolor, img2->bgcolor,
premultiply) && ok;
}
for (i = 0; i < img1->num_frames; ++i) {
// Pixel-by-pixel comparison.
const uint8_t* const rgba1 = img1->frames[i].rgba;
const uint8_t* const rgba2 = img2->frames[i].rgba;
int max_diff;
double psnr;
if (is_multi_frame_image) { // Check relevant for multi-frame images only.
const char format[] = "Frame #%d, duration mismatch";
char tmp[sizeof(format) + 8];
ok = ok && (snprintf(tmp, sizeof(tmp), format, i) >= 0);
ok = ok && CompareValues(img1->frames[i].duration,
img2->frames[i].duration, tmp);
}
GetDiffAndPSNR(rgba1, rgba2, img1->canvas_width, img1->canvas_height,
premultiply, &max_diff, &psnr);
if (min_psnr > 0.) {
if (psnr < min_psnr) {
fprintf(stderr, "Frame #%d, psnr = %.2lf (min_psnr = %f)\n", i,
psnr, min_psnr);
ok = 0;
}
} else {
if (max_diff != 0) {
fprintf(stderr, "Frame #%d, max pixel diff: %d\n", i, max_diff);
ok = 0;
}
}
}
return ok;
}
static void Help(void) {
printf("Usage: anim_diff <image1> <image2> [options]\n");
printf("\nOptions:\n");
printf(" -dump_frames <folder> dump decoded frames in PAM format\n");
printf(" -min_psnr <float> ... minimum per-frame PSNR\n");
printf(" -raw_comparison ..... if this flag is not used, RGB is\n");
printf(" premultiplied before comparison\n");
printf(" -max_diff <int> ..... maximum allowed difference per channel\n"
" between corresponding pixels in subsequent\n"
" frames\n");
printf(" -h .................. this help\n");
printf(" -version ............ print version number and exit\n");
}
int main(int argc, const char* argv[]) {
int return_code = -1;
int dump_frames = 0;
const char* dump_folder = NULL;
double min_psnr = 0.;
int got_input1 = 0;
int got_input2 = 0;
int premultiply = 1;
int max_diff = 0;
int i, c;
const char* files[2] = { NULL, NULL };
AnimatedImage images[2];
for (c = 1; c < argc; ++c) {
int parse_error = 0;
if (!strcmp(argv[c], "-dump_frames")) {
if (c < argc - 1) {
dump_frames = 1;
dump_folder = argv[++c];
} else {
parse_error = 1;
}
} else if (!strcmp(argv[c], "-min_psnr")) {
if (c < argc - 1) {
const char* const v = argv[++c];
char* end = NULL;
const double d = strtod(v, &end);
if (end == v) {
parse_error = 1;
fprintf(stderr, "Error! '%s' is not a floating point number.\n", v);
}
min_psnr = d;
} else {
parse_error = 1;
}
} else if (!strcmp(argv[c], "-raw_comparison")) {
premultiply = 0;
} else if (!strcmp(argv[c], "-max_diff")) {
if (c < argc - 1) {
const char* const v = argv[++c];
char* end = NULL;
const int n = (int)strtol(v, &end, 10);
if (end == v) {
parse_error = 1;
fprintf(stderr, "Error! '%s' is not an integer.\n", v);
}
max_diff = n;
} else {
parse_error = 1;
}
} else if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
Help();
return 0;
} else if (!strcmp(argv[c], "-version")) {
int dec_version, demux_version;
GetAnimatedImageVersions(&dec_version, &demux_version);
printf("WebP Decoder version: %d.%d.%d\nWebP Demux version: %d.%d.%d\n",
(dec_version >> 16) & 0xff, (dec_version >> 8) & 0xff,
(dec_version >> 0) & 0xff,
(demux_version >> 16) & 0xff, (demux_version >> 8) & 0xff,
(demux_version >> 0) & 0xff);
return 0;
} else {
if (!got_input1) {
files[0] = argv[c];
got_input1 = 1;
} else if (!got_input2) {
files[1] = argv[c];
got_input2 = 1;
} else {
parse_error = 1;
}
}
if (parse_error) {
Help();
return -1;
}
}
if (argc < 3) {
Help();
return -1;
}
if (!got_input2) {
Help();
return -1;
}
if (dump_frames) {
printf("Dumping decoded frames in: %s\n", dump_folder);
}
memset(images, 0, sizeof(images));
for (i = 0; i < 2; ++i) {
printf("Decoding file: %s\n", files[i]);
if (!ReadAnimatedImage(files[i], &images[i], dump_frames, dump_folder)) {
fprintf(stderr, "Error decoding file: %s\n Aborting.\n", files[i]);
return_code = -2;
goto End;
} else {
MinimizeAnimationFrames(&images[i], max_diff);
}
}
if (!CompareAnimatedImagePair(&images[0], &images[1],
premultiply, min_psnr)) {
fprintf(stderr, "\nFiles %s and %s differ.\n", files[0], files[1]);
return_code = -3;
} else {
printf("\nFiles %s and %s are identical.\n", files[0], files[1]);
return_code = 0;
}
End:
ClearAnimatedImage(&images[0]);
ClearAnimatedImage(&images[1]);
return return_code;
}