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libwebp/examples/anim_util.c
James Zern 09333097ed gif2webp: force low duration frames to 100ms 
this is consistent with web browser behavior as well as various
transcoding tools (ffmpeg, gif2apng, etc).

also: update anim_diff to account for this new behaviour.

BUG=webp:379

Change-Id: I70cc72a6b401ef32b73cd182a3f12d993d495bf4
2018-03-24 08:26:53 +01:00

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// 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.
// -----------------------------------------------------------------------------
//
// Utilities for animated images
#include "./anim_util.h"
#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
#if defined(WEBP_HAVE_GIF)
#include <gif_lib.h>
#endif
#include "webp/format_constants.h"
#include "webp/decode.h"
#include "webp/demux.h"
#include "../imageio/imageio_util.h"
#if defined(_MSC_VER) && _MSC_VER < 1900
#define snprintf _snprintf
#endif
static const int kNumChannels = 4;
// -----------------------------------------------------------------------------
// Common utilities.
#if defined(WEBP_HAVE_GIF)
// Returns true if the frame covers the full canvas.
static int IsFullFrame(int width, int height,
int canvas_width, int canvas_height) {
return (width == canvas_width && height == canvas_height);
}
#endif // WEBP_HAVE_GIF
static int CheckSizeForOverflow(uint64_t size) {
return (size == (size_t)size);
}
static int AllocateFrames(AnimatedImage* const image, uint32_t num_frames) {
uint32_t i;
uint8_t* mem = NULL;
DecodedFrame* frames = NULL;
const uint64_t rgba_size =
(uint64_t)image->canvas_width * kNumChannels * image->canvas_height;
const uint64_t total_size = (uint64_t)num_frames * rgba_size * sizeof(*mem);
const uint64_t total_frame_size = (uint64_t)num_frames * sizeof(*frames);
if (!CheckSizeForOverflow(total_size) ||
!CheckSizeForOverflow(total_frame_size)) {
return 0;
}
mem = (uint8_t*)malloc((size_t)total_size);
frames = (DecodedFrame*)malloc((size_t)total_frame_size);
if (mem == NULL || frames == NULL) {
free(mem);
free(frames);
return 0;
}
free(image->raw_mem);
image->num_frames = num_frames;
image->frames = frames;
for (i = 0; i < num_frames; ++i) {
frames[i].rgba = mem + i * rgba_size;
frames[i].duration = 0;
frames[i].is_key_frame = 0;
}
image->raw_mem = mem;
return 1;
}
void ClearAnimatedImage(AnimatedImage* const image) {
if (image != NULL) {
free(image->raw_mem);
free(image->frames);
image->num_frames = 0;
image->frames = NULL;
image->raw_mem = NULL;
}
}
#if defined(WEBP_HAVE_GIF)
// Clear the canvas to transparent.
static void ZeroFillCanvas(uint8_t* rgba,
uint32_t canvas_width, uint32_t canvas_height) {
memset(rgba, 0, canvas_width * kNumChannels * canvas_height);
}
// Clear given frame rectangle to transparent.
static void ZeroFillFrameRect(uint8_t* rgba, int rgba_stride, int x_offset,
int y_offset, int width, int height) {
int j;
assert(width * kNumChannels <= rgba_stride);
rgba += y_offset * rgba_stride + x_offset * kNumChannels;
for (j = 0; j < height; ++j) {
memset(rgba, 0, width * kNumChannels);
rgba += rgba_stride;
}
}
// Copy width * height pixels from 'src' to 'dst'.
static void CopyCanvas(const uint8_t* src, uint8_t* dst,
uint32_t width, uint32_t height) {
assert(src != NULL && dst != NULL);
memcpy(dst, src, width * kNumChannels * height);
}
// Copy pixels in the given rectangle from 'src' to 'dst' honoring the 'stride'.
static void CopyFrameRectangle(const uint8_t* src, uint8_t* dst, int stride,
int x_offset, int y_offset,
int width, int height) {
int j;
const int width_in_bytes = width * kNumChannels;
const size_t offset = y_offset * stride + x_offset * kNumChannels;
assert(width_in_bytes <= stride);
src += offset;
dst += offset;
for (j = 0; j < height; ++j) {
memcpy(dst, src, width_in_bytes);
src += stride;
dst += stride;
}
}
#endif // WEBP_HAVE_GIF
// Canonicalize all transparent pixels to transparent black to aid comparison.
static void CleanupTransparentPixels(uint32_t* rgba,
uint32_t width, uint32_t height) {
const uint32_t* const rgba_end = rgba + width * height;
while (rgba < rgba_end) {
const uint8_t alpha = (*rgba >> 24) & 0xff;
if (alpha == 0) {
*rgba = 0;
}
++rgba;
}
}
// Dump frame to a PAM file. Returns true on success.
static int DumpFrame(const char filename[], const char dump_folder[],
uint32_t frame_num, const uint8_t rgba[],
int canvas_width, int canvas_height) {
int ok = 0;
size_t max_len;
int y;
const char* base_name = NULL;
char* file_name = NULL;
FILE* f = NULL;
const char* row;
if (dump_folder == NULL) dump_folder = ".";
base_name = strrchr(filename, '/');
base_name = (base_name == NULL) ? filename : base_name + 1;
max_len = strlen(dump_folder) + 1 + strlen(base_name)
+ strlen("_frame_") + strlen(".pam") + 8;
file_name = (char*)malloc(max_len * sizeof(*file_name));
if (file_name == NULL) goto End;
if (snprintf(file_name, max_len, "%s/%s_frame_%d.pam",
dump_folder, base_name, frame_num) < 0) {
fprintf(stderr, "Error while generating file name\n");
goto End;
}
f = fopen(file_name, "wb");
if (f == NULL) {
fprintf(stderr, "Error opening file for writing: %s\n", file_name);
ok = 0;
goto End;
}
if (fprintf(f, "P7\nWIDTH %d\nHEIGHT %d\n"
"DEPTH 4\nMAXVAL 255\nTUPLTYPE RGB_ALPHA\nENDHDR\n",
canvas_width, canvas_height) < 0) {
fprintf(stderr, "Write error for file %s\n", file_name);
goto End;
}
row = (const char*)rgba;
for (y = 0; y < canvas_height; ++y) {
if (fwrite(row, canvas_width * kNumChannels, 1, f) != 1) {
fprintf(stderr, "Error writing to file: %s\n", file_name);
goto End;
}
row += canvas_width * kNumChannels;
}
ok = 1;
End:
if (f != NULL) fclose(f);
free(file_name);
return ok;
}
// -----------------------------------------------------------------------------
// WebP Decoding.
// Returns true if this is a valid WebP bitstream.
static int IsWebP(const WebPData* const webp_data) {
return (WebPGetInfo(webp_data->bytes, webp_data->size, NULL, NULL) != 0);
}
// Read animated WebP bitstream 'webp_data' into 'AnimatedImage' struct.
static int ReadAnimatedWebP(const char filename[],
const WebPData* const webp_data,
AnimatedImage* const image, int dump_frames,
const char dump_folder[]) {
int ok = 0;
int dump_ok = 1;
uint32_t frame_index = 0;
int prev_frame_timestamp = 0;
WebPAnimDecoder* dec;
WebPAnimInfo anim_info;
memset(image, 0, sizeof(*image));
dec = WebPAnimDecoderNew(webp_data, NULL);
if (dec == NULL) {
fprintf(stderr, "Error parsing image: %s\n", filename);
goto End;
}
if (!WebPAnimDecoderGetInfo(dec, &anim_info)) {
fprintf(stderr, "Error getting global info about the animation\n");
goto End;
}
// Animation properties.
image->canvas_width = anim_info.canvas_width;
image->canvas_height = anim_info.canvas_height;
image->loop_count = anim_info.loop_count;
image->bgcolor = anim_info.bgcolor;
// Allocate frames.
if (!AllocateFrames(image, anim_info.frame_count)) return 0;
// Decode frames.
while (WebPAnimDecoderHasMoreFrames(dec)) {
DecodedFrame* curr_frame;
uint8_t* curr_rgba;
uint8_t* frame_rgba;
int timestamp;
if (!WebPAnimDecoderGetNext(dec, &frame_rgba, &timestamp)) {
fprintf(stderr, "Error decoding frame #%u\n", frame_index);
goto End;
}
assert(frame_index < anim_info.frame_count);
curr_frame = &image->frames[frame_index];
curr_rgba = curr_frame->rgba;
curr_frame->duration = timestamp - prev_frame_timestamp;
curr_frame->is_key_frame = 0; // Unused.
memcpy(curr_rgba, frame_rgba,
image->canvas_width * kNumChannels * image->canvas_height);
// Needed only because we may want to compare with GIF later.
CleanupTransparentPixels((uint32_t*)curr_rgba,
image->canvas_width, image->canvas_height);
if (dump_frames && dump_ok) {
dump_ok = DumpFrame(filename, dump_folder, frame_index, curr_rgba,
image->canvas_width, image->canvas_height);
if (!dump_ok) { // Print error once, but continue decode loop.
fprintf(stderr, "Error dumping frames to %s\n", dump_folder);
}
}
++frame_index;
prev_frame_timestamp = timestamp;
}
ok = dump_ok;
End:
WebPAnimDecoderDelete(dec);
return ok;
}
// -----------------------------------------------------------------------------
// GIF Decoding.
#if defined(WEBP_HAVE_GIF)
// Returns true if this is a valid GIF bitstream.
static int IsGIF(const WebPData* const data) {
return data->size > GIF_STAMP_LEN &&
(!memcmp(GIF_STAMP, data->bytes, GIF_STAMP_LEN) ||
!memcmp(GIF87_STAMP, data->bytes, GIF_STAMP_LEN) ||
!memcmp(GIF89_STAMP, data->bytes, GIF_STAMP_LEN));
}
// GIFLIB_MAJOR is only defined in libgif >= 4.2.0.
#if defined(GIFLIB_MAJOR) && defined(GIFLIB_MINOR)
# define LOCAL_GIF_VERSION ((GIFLIB_MAJOR << 8) | GIFLIB_MINOR)
# define LOCAL_GIF_PREREQ(maj, min) \
(LOCAL_GIF_VERSION >= (((maj) << 8) | (min)))
#else
# define LOCAL_GIF_VERSION 0
# define LOCAL_GIF_PREREQ(maj, min) 0
#endif
#if !LOCAL_GIF_PREREQ(5, 0)
// Added in v5.0
typedef struct {
int DisposalMode;
#define DISPOSAL_UNSPECIFIED 0 // No disposal specified
#define DISPOSE_DO_NOT 1 // Leave image in place
#define DISPOSE_BACKGROUND 2 // Set area to background color
#define DISPOSE_PREVIOUS 3 // Restore to previous content
int UserInputFlag; // User confirmation required before disposal
int DelayTime; // Pre-display delay in 0.01sec units
int TransparentColor; // Palette index for transparency, -1 if none
#define NO_TRANSPARENT_COLOR -1
} GraphicsControlBlock;
static int DGifExtensionToGCB(const size_t GifExtensionLength,
const GifByteType* GifExtension,
GraphicsControlBlock* gcb) {
if (GifExtensionLength != 4) {
return GIF_ERROR;
}
gcb->DisposalMode = (GifExtension[0] >> 2) & 0x07;
gcb->UserInputFlag = (GifExtension[0] & 0x02) != 0;
gcb->DelayTime = GifExtension[1] | (GifExtension[2] << 8);
if (GifExtension[0] & 0x01) {
gcb->TransparentColor = (int)GifExtension[3];
} else {
gcb->TransparentColor = NO_TRANSPARENT_COLOR;
}
return GIF_OK;
}
static int DGifSavedExtensionToGCB(GifFileType* GifFile, int ImageIndex,
GraphicsControlBlock* gcb) {
int i;
if (ImageIndex < 0 || ImageIndex > GifFile->ImageCount - 1) {
return GIF_ERROR;
}
gcb->DisposalMode = DISPOSAL_UNSPECIFIED;
gcb->UserInputFlag = 0;
gcb->DelayTime = 0;
gcb->TransparentColor = NO_TRANSPARENT_COLOR;
for (i = 0; i < GifFile->SavedImages[ImageIndex].ExtensionBlockCount; i++) {
ExtensionBlock* ep = &GifFile->SavedImages[ImageIndex].ExtensionBlocks[i];
if (ep->Function == GRAPHICS_EXT_FUNC_CODE) {
return DGifExtensionToGCB(
ep->ByteCount, (const GifByteType*)ep->Bytes, gcb);
}
}
return GIF_ERROR;
}
#define CONTINUE_EXT_FUNC_CODE 0x00
// Signature was changed in v5.0
#define DGifOpenFileName(a, b) DGifOpenFileName(a)
#endif // !LOCAL_GIF_PREREQ(5, 0)
// Signature changed in v5.1
#if !LOCAL_GIF_PREREQ(5, 1)
#define DGifCloseFile(a, b) DGifCloseFile(a)
#endif
static void GIFDisplayError(const GifFileType* const gif, int gif_error) {
// libgif 4.2.0 has retired PrintGifError() and added GifErrorString().
#if LOCAL_GIF_PREREQ(4, 2)
#if LOCAL_GIF_PREREQ(5, 0)
const char* error_str =
GifErrorString((gif == NULL) ? gif_error : gif->Error);
#else
const char* error_str = GifErrorString();
(void)gif;
#endif
if (error_str == NULL) error_str = "Unknown error";
fprintf(stderr, "GIFLib Error %d: %s\n", gif_error, error_str);
#else
(void)gif;
fprintf(stderr, "GIFLib Error %d: ", gif_error);
PrintGifError();
fprintf(stderr, "\n");
#endif
}
static int IsKeyFrameGIF(const GifImageDesc* prev_desc, int prev_dispose,
const DecodedFrame* const prev_frame,
int canvas_width, int canvas_height) {
if (prev_frame == NULL) return 1;
if (prev_dispose == DISPOSE_BACKGROUND) {
if (IsFullFrame(prev_desc->Width, prev_desc->Height,
canvas_width, canvas_height)) {
return 1;
}
if (prev_frame->is_key_frame) return 1;
}
return 0;
}
static int GetTransparentIndexGIF(GifFileType* gif) {
GraphicsControlBlock first_gcb;
memset(&first_gcb, 0, sizeof(first_gcb));
DGifSavedExtensionToGCB(gif, 0, &first_gcb);
return first_gcb.TransparentColor;
}
static uint32_t GetBackgroundColorGIF(GifFileType* gif) {
const int transparent_index = GetTransparentIndexGIF(gif);
const ColorMapObject* const color_map = gif->SColorMap;
if (transparent_index != NO_TRANSPARENT_COLOR &&
gif->SBackGroundColor == transparent_index) {
return 0x00000000; // Special case: transparent black.
} else if (color_map == NULL || color_map->Colors == NULL
|| gif->SBackGroundColor >= color_map->ColorCount) {
return 0xffffffff; // Invalid: assume white.
} else {
const GifColorType color = color_map->Colors[gif->SBackGroundColor];
return (0xff << 24) |
(color.Red << 16) |
(color.Green << 8) |
(color.Blue << 0);
}
}
// Find appropriate app extension and get loop count from the next extension.
// We use Chrome's interpretation of the 'loop_count' semantics:
// if not present -> loop once
// if present and loop_count == 0, return 0 ('infinite').
// if present and loop_count != 0, it's the number of *extra* loops
// so we need to return loop_count + 1 as total loop number.
static uint32_t GetLoopCountGIF(const GifFileType* const gif) {
int i;
for (i = 0; i < gif->ImageCount; ++i) {
const SavedImage* const image = &gif->SavedImages[i];
int j;
for (j = 0; (j + 1) < image->ExtensionBlockCount; ++j) {
const ExtensionBlock* const eb1 = image->ExtensionBlocks + j;
const ExtensionBlock* const eb2 = image->ExtensionBlocks + j + 1;
const char* const signature = (const char*)eb1->Bytes;
const int signature_is_ok =
(eb1->Function == APPLICATION_EXT_FUNC_CODE) &&
(eb1->ByteCount == 11) &&
(!memcmp(signature, "NETSCAPE2.0", 11) ||
!memcmp(signature, "ANIMEXTS1.0", 11));
if (signature_is_ok &&
eb2->Function == CONTINUE_EXT_FUNC_CODE && eb2->ByteCount >= 3 &&
eb2->Bytes[0] == 1) {
const uint32_t extra_loop = ((uint32_t)(eb2->Bytes[2]) << 8) +
((uint32_t)(eb2->Bytes[1]) << 0);
return (extra_loop > 0) ? extra_loop + 1 : 0;
}
}
}
return 1; // Default.
}
// Get duration of 'n'th frame in milliseconds.
static int GetFrameDurationGIF(GifFileType* gif, int n) {
GraphicsControlBlock gcb;
memset(&gcb, 0, sizeof(gcb));
DGifSavedExtensionToGCB(gif, n, &gcb);
return gcb.DelayTime * 10;
}
// Returns true if frame 'target' completely covers 'covered'.
static int CoversFrameGIF(const GifImageDesc* const target,
const GifImageDesc* const covered) {
return target->Left <= covered->Left &&
covered->Left + covered->Width <= target->Left + target->Width &&
target->Top <= covered->Top &&
covered->Top + covered->Height <= target->Top + target->Height;
}
static void RemapPixelsGIF(const uint8_t* const src,
const ColorMapObject* const cmap,
int transparent_color, int len, uint8_t* dst) {
int i;
for (i = 0; i < len; ++i) {
if (src[i] != transparent_color) {
// If a pixel in the current frame is transparent, we don't modify it, so
// that we can see-through the corresponding pixel from an earlier frame.
const GifColorType c = cmap->Colors[src[i]];
dst[4 * i + 0] = c.Red;
dst[4 * i + 1] = c.Green;
dst[4 * i + 2] = c.Blue;
dst[4 * i + 3] = 0xff;
}
}
}
static int ReadFrameGIF(const SavedImage* const gif_image,
const ColorMapObject* cmap, int transparent_color,
int out_stride, uint8_t* const dst) {
const GifImageDesc* image_desc = &gif_image->ImageDesc;
const uint8_t* in;
uint8_t* out;
int j;
if (image_desc->ColorMap) cmap = image_desc->ColorMap;
if (cmap == NULL || cmap->ColorCount != (1 << cmap->BitsPerPixel)) {
fprintf(stderr, "Potentially corrupt color map.\n");
return 0;
}
in = (const uint8_t*)gif_image->RasterBits;
out = dst + image_desc->Top * out_stride + image_desc->Left * kNumChannels;
for (j = 0; j < image_desc->Height; ++j) {
RemapPixelsGIF(in, cmap, transparent_color, image_desc->Width, out);
in += image_desc->Width;
out += out_stride;
}
return 1;
}
// Read animated GIF bitstream from 'filename' into 'AnimatedImage' struct.
static int ReadAnimatedGIF(const char filename[], AnimatedImage* const image,
int dump_frames, const char dump_folder[]) {
uint32_t frame_count;
uint32_t canvas_width, canvas_height;
uint32_t i;
int gif_error;
GifFileType* gif;
gif = DGifOpenFileName(filename, NULL);
if (gif == NULL) {
fprintf(stderr, "Could not read file: %s.\n", filename);
return 0;
}
gif_error = DGifSlurp(gif);
if (gif_error != GIF_OK) {
fprintf(stderr, "Could not parse image: %s.\n", filename);
GIFDisplayError(gif, gif_error);
DGifCloseFile(gif, NULL);
return 0;
}
// Animation properties.
image->canvas_width = (uint32_t)gif->SWidth;
image->canvas_height = (uint32_t)gif->SHeight;
if (image->canvas_width > MAX_CANVAS_SIZE ||
image->canvas_height > MAX_CANVAS_SIZE) {
fprintf(stderr, "Invalid canvas dimension: %d x %d\n",
image->canvas_width, image->canvas_height);
DGifCloseFile(gif, NULL);
return 0;
}
image->loop_count = GetLoopCountGIF(gif);
image->bgcolor = GetBackgroundColorGIF(gif);
frame_count = (uint32_t)gif->ImageCount;
if (frame_count == 0) {
DGifCloseFile(gif, NULL);
return 0;
}
if (image->canvas_width == 0 || image->canvas_height == 0) {
image->canvas_width = gif->SavedImages[0].ImageDesc.Width;
image->canvas_height = gif->SavedImages[0].ImageDesc.Height;
gif->SavedImages[0].ImageDesc.Left = 0;
gif->SavedImages[0].ImageDesc.Top = 0;
if (image->canvas_width == 0 || image->canvas_height == 0) {
fprintf(stderr, "Invalid canvas size in GIF.\n");
DGifCloseFile(gif, NULL);
return 0;
}
}
// Allocate frames.
AllocateFrames(image, frame_count);
canvas_width = image->canvas_width;
canvas_height = image->canvas_height;
// Decode and reconstruct frames.
for (i = 0; i < frame_count; ++i) {
const int canvas_width_in_bytes = canvas_width * kNumChannels;
const SavedImage* const curr_gif_image = &gif->SavedImages[i];
GraphicsControlBlock curr_gcb;
DecodedFrame* curr_frame;
uint8_t* curr_rgba;
memset(&curr_gcb, 0, sizeof(curr_gcb));
DGifSavedExtensionToGCB(gif, i, &curr_gcb);
curr_frame = &image->frames[i];
curr_rgba = curr_frame->rgba;
curr_frame->duration = GetFrameDurationGIF(gif, i);
// Force frames with a small or no duration to 100ms to be consistent
// with web browsers and other transcoding tools (like gif2webp itself).
if (curr_frame->duration <= 10) curr_frame->duration = 100;
if (i == 0) { // Initialize as transparent.
curr_frame->is_key_frame = 1;
ZeroFillCanvas(curr_rgba, canvas_width, canvas_height);
} else {
DecodedFrame* const prev_frame = &image->frames[i - 1];
const GifImageDesc* const prev_desc = &gif->SavedImages[i - 1].ImageDesc;
GraphicsControlBlock prev_gcb;
memset(&prev_gcb, 0, sizeof(prev_gcb));
DGifSavedExtensionToGCB(gif, i - 1, &prev_gcb);
curr_frame->is_key_frame =
IsKeyFrameGIF(prev_desc, prev_gcb.DisposalMode, prev_frame,
canvas_width, canvas_height);
if (curr_frame->is_key_frame) { // Initialize as transparent.
ZeroFillCanvas(curr_rgba, canvas_width, canvas_height);
} else {
int prev_frame_disposed, curr_frame_opaque;
int prev_frame_completely_covered;
// Initialize with previous canvas.
uint8_t* const prev_rgba = image->frames[i - 1].rgba;
CopyCanvas(prev_rgba, curr_rgba, canvas_width, canvas_height);
// Dispose previous frame rectangle.
prev_frame_disposed =
(prev_gcb.DisposalMode == DISPOSE_BACKGROUND ||
prev_gcb.DisposalMode == DISPOSE_PREVIOUS);
curr_frame_opaque =
(curr_gcb.TransparentColor == NO_TRANSPARENT_COLOR);
prev_frame_completely_covered =
curr_frame_opaque &&
CoversFrameGIF(&curr_gif_image->ImageDesc, prev_desc);
if (prev_frame_disposed && !prev_frame_completely_covered) {
switch (prev_gcb.DisposalMode) {
case DISPOSE_BACKGROUND: {
ZeroFillFrameRect(curr_rgba, canvas_width_in_bytes,
prev_desc->Left, prev_desc->Top,
prev_desc->Width, prev_desc->Height);
break;
}
case DISPOSE_PREVIOUS: {
int src_frame_num = i - 2;
while (src_frame_num >= 0) {
GraphicsControlBlock src_frame_gcb;
memset(&src_frame_gcb, 0, sizeof(src_frame_gcb));
DGifSavedExtensionToGCB(gif, src_frame_num, &src_frame_gcb);
if (src_frame_gcb.DisposalMode != DISPOSE_PREVIOUS) break;
--src_frame_num;
}
if (src_frame_num >= 0) {
// Restore pixels inside previous frame rectangle to
// corresponding pixels in source canvas.
uint8_t* const src_frame_rgba =
image->frames[src_frame_num].rgba;
CopyFrameRectangle(src_frame_rgba, curr_rgba,
canvas_width_in_bytes,
prev_desc->Left, prev_desc->Top,
prev_desc->Width, prev_desc->Height);
} else {
// Source canvas doesn't exist. So clear previous frame
// rectangle to background.
ZeroFillFrameRect(curr_rgba, canvas_width_in_bytes,
prev_desc->Left, prev_desc->Top,
prev_desc->Width, prev_desc->Height);
}
break;
}
default:
break; // Nothing to do.
}
}
}
}
// Decode current frame.
if (!ReadFrameGIF(curr_gif_image, gif->SColorMap, curr_gcb.TransparentColor,
canvas_width_in_bytes, curr_rgba)) {
DGifCloseFile(gif, NULL);
return 0;
}
if (dump_frames) {
if (!DumpFrame(filename, dump_folder, i, curr_rgba,
canvas_width, canvas_height)) {
DGifCloseFile(gif, NULL);
return 0;
}
}
}
DGifCloseFile(gif, NULL);
return 1;
}
#else
static int IsGIF(const WebPData* const data) {
(void)data;
return 0;
}
static int ReadAnimatedGIF(const char filename[], AnimatedImage* const image,
int dump_frames, const char dump_folder[]) {
(void)filename;
(void)image;
(void)dump_frames;
(void)dump_folder;
fprintf(stderr, "GIF support not compiled. Please install the libgif-dev "
"package before building.\n");
return 0;
}
#endif // WEBP_HAVE_GIF
// -----------------------------------------------------------------------------
int ReadAnimatedImage(const char filename[], AnimatedImage* const image,
int dump_frames, const char dump_folder[]) {
int ok = 0;
WebPData webp_data;
WebPDataInit(&webp_data);
memset(image, 0, sizeof(*image));
if (!ImgIoUtilReadFile(filename, &webp_data.bytes, &webp_data.size)) {
fprintf(stderr, "Error reading file: %s\n", filename);
return 0;
}
if (IsWebP(&webp_data)) {
ok = ReadAnimatedWebP(filename, &webp_data, image, dump_frames,
dump_folder);
} else if (IsGIF(&webp_data)) {
ok = ReadAnimatedGIF(filename, image, dump_frames, dump_folder);
} else {
fprintf(stderr,
"Unknown file type: %s. Supported file types are WebP and GIF\n",
filename);
ok = 0;
}
if (!ok) ClearAnimatedImage(image);
WebPDataClear(&webp_data);
return ok;
}
static void Accumulate(double v1, double v2, double* const max_diff,
double* const sse) {
const double diff = fabs(v1 - v2);
if (diff > *max_diff) *max_diff = diff;
*sse += diff * diff;
}
void GetDiffAndPSNR(const uint8_t rgba1[], const uint8_t rgba2[],
uint32_t width, uint32_t height, int premultiply,
int* const max_diff, double* const psnr) {
const uint32_t stride = width * kNumChannels;
const int kAlphaChannel = kNumChannels - 1;
double f_max_diff = 0.;
double sse = 0.;
uint32_t x, y;
for (y = 0; y < height; ++y) {
for (x = 0; x < stride; x += kNumChannels) {
int k;
const size_t offset = (size_t)y * stride + x;
const int alpha1 = rgba1[offset + kAlphaChannel];
const int alpha2 = rgba2[offset + kAlphaChannel];
Accumulate(alpha1, alpha2, &f_max_diff, &sse);
if (!premultiply) {
for (k = 0; k < kAlphaChannel; ++k) {
Accumulate(rgba1[offset + k], rgba2[offset + k], &f_max_diff, &sse);
}
} else {
// premultiply R/G/B channels with alpha value
for (k = 0; k < kAlphaChannel; ++k) {
Accumulate(rgba1[offset + k] * alpha1 / 255.,
rgba2[offset + k] * alpha2 / 255.,
&f_max_diff, &sse);
}
}
}
}
*max_diff = (int)f_max_diff;
if (*max_diff == 0) {
*psnr = 99.; // PSNR when images are identical.
} else {
sse /= stride * height;
*psnr = 4.3429448 * log(255. * 255. / sse);
}
}
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