libwebp/examples/gif2webp.c
Urvang Joshi e297fc7171 gif2webp: Use the default hint instead of WEBP_HINT_GRAPH.
This is much faster and the compression is slightly better too.

(cherry picked from commit c94ed49efd)

Change-Id: Ibf0d10eea83bfabfcc44ee497074767462ff41b1
2015-03-02 18:42:54 -08:00

722 lines
24 KiB
C
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// Copyright 2012 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.
// -----------------------------------------------------------------------------
//
// simple tool to convert animated GIFs to WebP
//
// Authors: Skal (pascal.massimino@gmail.com)
// Urvang (urvang@google.com)
#include <assert.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_CONFIG_H
#include "webp/config.h"
#endif
#ifdef WEBP_HAVE_GIF
#include <gif_lib.h>
#include "webp/encode.h"
#include "webp/mux.h"
#include "./example_util.h"
#include "./gif2webp_util.h"
// 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
#define GIF_TRANSPARENT_MASK 0x01
#define GIF_DISPOSE_MASK 0x07
#define GIF_DISPOSE_SHIFT 2
#define WHITE_COLOR 0xffffffff
#define MAX_CACHE_SIZE 30
//------------------------------------------------------------------------------
static int transparent_index = -1; // Opaque frame by default.
static void SanitizeKeyFrameIntervals(size_t* const kmin_ptr,
size_t* const kmax_ptr) {
size_t kmin = *kmin_ptr;
size_t kmax = *kmax_ptr;
int print_warning = 1;
if (kmin == 0) { // Disable keyframe insertion.
kmax = ~0;
kmin = kmax - 1;
print_warning = 0;
}
if (kmax == 0) {
kmax = ~0;
print_warning = 0;
}
if (kmin >= kmax) {
kmin = kmax - 1;
if (print_warning) {
fprintf(stderr,
"WARNING: Setting kmin = %d, so that kmin < kmax.\n", (int)kmin);
}
} else if (kmin < (kmax / 2 + 1)) {
// This ensures that cache.keyframe + kmin >= kmax is always true. So, we
// can flush all the frames in the count_since_key_frame == kmax case.
kmin = (kmax / 2 + 1);
if (print_warning) {
fprintf(stderr,
"WARNING: Setting kmin = %d, so that kmin >= kmax / 2 + 1.\n",
(int)kmin);
}
}
// Limit the max number of frames that are allocated.
if (kmax - kmin > MAX_CACHE_SIZE) {
kmin = kmax - MAX_CACHE_SIZE;
if (print_warning) {
fprintf(stderr,
"WARNING: Setting kmin = %d, so that kmax - kmin <= 30.\n",
(int)kmin);
}
}
*kmin_ptr = kmin;
*kmax_ptr = kmax;
}
static void Remap(const uint8_t* const src, const GifFileType* const gif,
uint32_t* dst, int len) {
int i;
const GifColorType* colors;
const ColorMapObject* const cmap =
gif->Image.ColorMap ? gif->Image.ColorMap : gif->SColorMap;
if (cmap == NULL) return;
colors = cmap->Colors;
for (i = 0; i < len; ++i) {
const GifColorType c = colors[src[i]];
dst[i] = (src[i] == transparent_index) ? WEBP_UTIL_TRANSPARENT_COLOR
: c.Blue | (c.Green << 8) | (c.Red << 16) | (0xff << 24);
}
}
// Read the GIF image frame.
static int ReadFrame(GifFileType* const gif, WebPFrameRect* const gif_rect,
WebPPicture* const webp_frame) {
WebPPicture sub_image;
const GifImageDesc* const image_desc = &gif->Image;
uint32_t* dst = NULL;
uint8_t* tmp = NULL;
int ok = 0;
WebPFrameRect rect = {
image_desc->Left, image_desc->Top, image_desc->Width, image_desc->Height
};
*gif_rect = rect;
// Use a view for the sub-picture:
if (!WebPPictureView(webp_frame, rect.x_offset, rect.y_offset,
rect.width, rect.height, &sub_image)) {
fprintf(stderr, "Sub-image %dx%d at position %d,%d is invalid!\n",
rect.width, rect.height, rect.x_offset, rect.y_offset);
return 0;
}
dst = sub_image.argb;
tmp = (uint8_t*)malloc(rect.width * sizeof(*tmp));
if (tmp == NULL) goto End;
if (image_desc->Interlace) { // Interlaced image.
// We need 4 passes, with the following offsets and jumps.
const int interlace_offsets[] = { 0, 4, 2, 1 };
const int interlace_jumps[] = { 8, 8, 4, 2 };
int pass;
for (pass = 0; pass < 4; ++pass) {
int y;
for (y = interlace_offsets[pass]; y < rect.height;
y += interlace_jumps[pass]) {
if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;
Remap(tmp, gif, dst + y * sub_image.argb_stride, rect.width);
}
}
} else { // Non-interlaced image.
int y;
for (y = 0; y < rect.height; ++y) {
if (DGifGetLine(gif, tmp, rect.width) == GIF_ERROR) goto End;
Remap(tmp, gif, dst + y * sub_image.argb_stride, rect.width);
}
}
ok = 1;
End:
if (!ok) webp_frame->error_code = sub_image.error_code;
WebPPictureFree(&sub_image);
free(tmp);
return ok;
}
static void GetBackgroundColor(const ColorMapObject* const color_map,
int bgcolor_idx, uint32_t* const bgcolor) {
if (transparent_index != -1 && bgcolor_idx == transparent_index) {
*bgcolor = WEBP_UTIL_TRANSPARENT_COLOR; // Special case.
} else if (color_map == NULL || color_map->Colors == NULL
|| bgcolor_idx >= color_map->ColorCount) {
*bgcolor = WHITE_COLOR;
fprintf(stderr,
"GIF decode warning: invalid background color index. Assuming "
"white background.\n");
} else {
const GifColorType color = color_map->Colors[bgcolor_idx];
*bgcolor = (0xff << 24)
| (color.Red << 16)
| (color.Green << 8)
| (color.Blue << 0);
}
}
static void DisplayGifError(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)
// Static string actually, hence the const char* cast.
const char* error_str = (const char*)GifErrorString(
(gif == NULL) ? gif_error : gif->Error);
#else
const char* error_str = (const char*)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 const char* const kErrorMessages[-WEBP_MUX_NOT_ENOUGH_DATA + 1] = {
"WEBP_MUX_NOT_FOUND", "WEBP_MUX_INVALID_ARGUMENT", "WEBP_MUX_BAD_DATA",
"WEBP_MUX_MEMORY_ERROR", "WEBP_MUX_NOT_ENOUGH_DATA"
};
static const char* ErrorString(WebPMuxError err) {
assert(err <= WEBP_MUX_NOT_FOUND && err >= WEBP_MUX_NOT_ENOUGH_DATA);
return kErrorMessages[-err];
}
enum {
METADATA_ICC = (1 << 0),
METADATA_XMP = (1 << 1),
METADATA_ALL = METADATA_ICC | METADATA_XMP
};
//------------------------------------------------------------------------------
static void Help(void) {
printf("Usage:\n");
printf(" gif2webp [options] gif_file -o webp_file\n");
printf("Options:\n");
printf(" -h / -help ............ this help\n");
printf(" -lossy ................. encode image using lossy compression\n");
printf(" -mixed ................. for each frame in the image, pick lossy\n"
" or lossless compression heuristically\n");
printf(" -q <float> ............. quality factor (0:small..100:big)\n");
printf(" -m <int> ............... compression method (0=fast, 6=slowest)\n");
printf(" -kmin <int> ............ min distance between key frames\n");
printf(" -kmax <int> ............ max distance between key frames\n");
printf(" -f <int> ............... filter strength (0=off..100)\n");
printf(" -metadata <string> ..... comma separated list of metadata to\n");
printf(" ");
printf("copy from the input to the output if present\n");
printf(" "
"Valid values: all, none, icc, xmp (default)\n");
printf(" -mt .................... use multi-threading if available\n");
printf("\n");
printf(" -version ............... print version number and exit\n");
printf(" -v ..................... verbose\n");
printf(" -quiet ................. don't print anything\n");
printf("\n");
}
//------------------------------------------------------------------------------
int main(int argc, const char *argv[]) {
int verbose = 0;
int gif_error = GIF_ERROR;
WebPMuxError err = WEBP_MUX_OK;
int ok = 0;
const char *in_file = NULL, *out_file = NULL;
FILE* out = NULL;
GifFileType* gif = NULL;
WebPConfig config;
WebPPicture frame;
int duration = 0;
FrameDisposeMethod orig_dispose = FRAME_DISPOSE_NONE;
WebPMuxAnimParams anim = { WHITE_COLOR, 0 };
WebPFrameCache* cache = NULL;
int is_first_frame = 1; // Whether we are processing the first frame.
int done;
int c;
int quiet = 0;
WebPMux* mux = NULL;
WebPData webp_data = { NULL, 0 };
int keep_metadata = METADATA_XMP; // ICC not output by default.
int stored_icc = 0; // Whether we have already stored an ICC profile.
int stored_xmp = 0;
int default_kmin = 1; // Whether to use default kmin value.
int default_kmax = 1;
size_t kmin = 0;
size_t kmax = 0;
int allow_mixed = 0; // If true, each frame can be lossy or lossless.
if (!WebPConfigInit(&config) || !WebPPictureInit(&frame)) {
fprintf(stderr, "Error! Version mismatch!\n");
return -1;
}
config.lossless = 1; // Use lossless compression by default.
if (argc == 1) {
Help();
return 0;
}
for (c = 1; c < argc; ++c) {
int parse_error = 0;
if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
Help();
return 0;
} else if (!strcmp(argv[c], "-o") && c < argc - 1) {
out_file = argv[++c];
} else if (!strcmp(argv[c], "-lossy")) {
config.lossless = 0;
} else if (!strcmp(argv[c], "-mixed")) {
allow_mixed = 1;
config.lossless = 0;
} else if (!strcmp(argv[c], "-q") && c < argc - 1) {
config.quality = ExUtilGetFloat(argv[++c], &parse_error);
} else if (!strcmp(argv[c], "-m") && c < argc - 1) {
config.method = ExUtilGetInt(argv[++c], 0, &parse_error);
} else if (!strcmp(argv[c], "-kmax") && c < argc - 1) {
kmax = ExUtilGetUInt(argv[++c], 0, &parse_error);
default_kmax = 0;
} else if (!strcmp(argv[c], "-kmin") && c < argc - 1) {
kmin = ExUtilGetUInt(argv[++c], 0, &parse_error);
default_kmin = 0;
} else if (!strcmp(argv[c], "-f") && c < argc - 1) {
config.filter_strength = ExUtilGetInt(argv[++c], 0, &parse_error);
} else if (!strcmp(argv[c], "-metadata") && c < argc - 1) {
static const struct {
const char* option;
int flag;
} kTokens[] = {
{ "all", METADATA_ALL },
{ "none", 0 },
{ "icc", METADATA_ICC },
{ "xmp", METADATA_XMP },
};
const size_t kNumTokens = sizeof(kTokens) / sizeof(*kTokens);
const char* start = argv[++c];
const char* const end = start + strlen(start);
keep_metadata = 0;
while (start < end) {
size_t i;
const char* token = strchr(start, ',');
if (token == NULL) token = end;
for (i = 0; i < kNumTokens; ++i) {
if ((size_t)(token - start) == strlen(kTokens[i].option) &&
!strncmp(start, kTokens[i].option, strlen(kTokens[i].option))) {
if (kTokens[i].flag != 0) {
keep_metadata |= kTokens[i].flag;
} else {
keep_metadata = 0;
}
break;
}
}
if (i == kNumTokens) {
fprintf(stderr, "Error! Unknown metadata type '%.*s'\n",
(int)(token - start), start);
Help();
return -1;
}
start = token + 1;
}
} else if (!strcmp(argv[c], "-mt")) {
++config.thread_level;
} else if (!strcmp(argv[c], "-version")) {
const int enc_version = WebPGetEncoderVersion();
const int mux_version = WebPGetMuxVersion();
printf("WebP Encoder version: %d.%d.%d\nWebP Mux version: %d.%d.%d\n",
(enc_version >> 16) & 0xff, (enc_version >> 8) & 0xff,
enc_version & 0xff, (mux_version >> 16) & 0xff,
(mux_version >> 8) & 0xff, mux_version & 0xff);
return 0;
} else if (!strcmp(argv[c], "-quiet")) {
quiet = 1;
} else if (!strcmp(argv[c], "-v")) {
verbose = 1;
} else if (!strcmp(argv[c], "--")) {
if (c < argc - 1) in_file = argv[++c];
break;
} else if (argv[c][0] == '-') {
fprintf(stderr, "Error! Unknown option '%s'\n", argv[c]);
Help();
return -1;
} else {
in_file = argv[c];
}
if (parse_error) {
Help();
return -1;
}
}
// Appropriate default kmin, kmax values for lossy and lossless.
if (default_kmin) {
kmin = config.lossless ? 9 : 3;
}
if (default_kmax) {
kmax = config.lossless ? 17 : 5;
}
SanitizeKeyFrameIntervals(&kmin, &kmax);
if (!WebPValidateConfig(&config)) {
fprintf(stderr, "Error! Invalid configuration.\n");
goto End;
}
if (in_file == NULL) {
fprintf(stderr, "No input file specified!\n");
Help();
goto End;
}
// Start the decoder object
#if LOCAL_GIF_PREREQ(5,0)
gif = DGifOpenFileName(in_file, &gif_error);
#else
gif = DGifOpenFileName(in_file);
#endif
if (gif == NULL) goto End;
mux = WebPMuxNew();
if (mux == NULL) {
fprintf(stderr, "ERROR: could not create a mux object.\n");
goto End;
}
// Loop over GIF images
done = 0;
do {
GifRecordType type;
if (DGifGetRecordType(gif, &type) == GIF_ERROR) goto End;
switch (type) {
case IMAGE_DESC_RECORD_TYPE: {
WebPFrameRect gif_rect;
GifImageDesc* const image_desc = &gif->Image;
if (!DGifGetImageDesc(gif)) goto End;
// Fix some broken GIF global headers that report
// 0 x 0 screen dimension.
if (is_first_frame) {
if (verbose) {
printf("Canvas screen: %d x %d\n", gif->SWidth, gif->SHeight);
}
if (gif->SWidth == 0 || gif->SHeight == 0) {
image_desc->Left = 0;
image_desc->Top = 0;
gif->SWidth = image_desc->Width;
gif->SHeight = image_desc->Height;
if (gif->SWidth <= 0 || gif->SHeight <= 0) {
goto End;
}
if (verbose) {
printf("Fixed canvas screen dimension to: %d x %d\n",
gif->SWidth, gif->SHeight);
}
}
#if WEBP_MUX_ABI_VERSION > 0x0101
// Set definitive canvas size.
err = WebPMuxSetCanvasSize(mux, gif->SWidth, gif->SHeight);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "Invalid canvas size %d x %d\n",
gif->SWidth, gif->SHeight);
goto End;
}
#endif
// Allocate current buffer.
frame.width = gif->SWidth;
frame.height = gif->SHeight;
frame.use_argb = 1;
if (!WebPPictureAlloc(&frame)) goto End;
WebPUtilClearPic(&frame, NULL);
// Initialize cache.
cache = WebPFrameCacheNew(frame.width, frame.height,
kmin, kmax, allow_mixed);
if (cache == NULL) goto End;
// Background color.
GetBackgroundColor(gif->SColorMap, gif->SBackGroundColor,
&anim.bgcolor);
}
// Some even more broken GIF can have sub-rect with zero width/height.
if (image_desc->Width == 0 || image_desc->Height == 0) {
image_desc->Width = gif->SWidth;
image_desc->Height = gif->SHeight;
}
if (!ReadFrame(gif, &gif_rect, &frame)) {
goto End;
}
if (!WebPFrameCacheAddFrame(cache, &config, &gif_rect, orig_dispose,
duration, &frame)) {
fprintf(stderr, "Error! Cannot encode frame as WebP\n");
fprintf(stderr, "Error code: %d\n", frame.error_code);
}
err = WebPFrameCacheFlush(cache, verbose, mux);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not add animation frame.\n",
ErrorString(err));
goto End;
}
is_first_frame = 0;
// In GIF, graphic control extensions are optional for a frame, so we
// may not get one before reading the next frame. To handle this case,
// we reset frame properties to reasonable defaults for the next frame.
orig_dispose = FRAME_DISPOSE_NONE;
duration = 0;
transparent_index = -1; // Opaque frame by default.
break;
}
case EXTENSION_RECORD_TYPE: {
int extension;
GifByteType *data = NULL;
if (DGifGetExtension(gif, &extension, &data) == GIF_ERROR) {
goto End;
}
switch (extension) {
case COMMENT_EXT_FUNC_CODE: {
break; // Do nothing for now.
}
case GRAPHICS_EXT_FUNC_CODE: {
const int flags = data[1];
const int dispose = (flags >> GIF_DISPOSE_SHIFT) & GIF_DISPOSE_MASK;
const int delay = data[2] | (data[3] << 8); // In 10 ms units.
if (data[0] != 4) goto End;
duration = delay * 10; // Duration is in 1 ms units for WebP.
switch (dispose) {
case 3:
orig_dispose = FRAME_DISPOSE_RESTORE_PREVIOUS;
break;
case 2:
orig_dispose = FRAME_DISPOSE_BACKGROUND;
break;
case 1:
case 0:
default:
orig_dispose = FRAME_DISPOSE_NONE;
break;
}
transparent_index = (flags & GIF_TRANSPARENT_MASK) ? data[4] : -1;
break;
}
case PLAINTEXT_EXT_FUNC_CODE: {
break;
}
case APPLICATION_EXT_FUNC_CODE: {
if (data[0] != 11) break; // Chunk is too short
if (!memcmp(data + 1, "NETSCAPE2.0", 11) ||
!memcmp(data + 1, "ANIMEXTS1.0", 11)) {
// Recognize and parse Netscape2.0 NAB extension for loop count.
if (DGifGetExtensionNext(gif, &data) == GIF_ERROR) goto End;
if (data == NULL) goto End; // Loop count sub-block missing.
if (data[0] < 3 || data[1] != 1) break; // wrong size/marker
anim.loop_count = data[2] | (data[3] << 8);
if (verbose) {
fprintf(stderr, "Loop count: %d\n", anim.loop_count);
}
} else { // An extension containing metadata.
// We only store the first encountered chunk of each type, and
// only if requested by the user.
const int is_xmp = (keep_metadata & METADATA_XMP) &&
!stored_xmp &&
!memcmp(data + 1, "XMP DataXMP", 11);
const int is_icc = (keep_metadata & METADATA_ICC) &&
!stored_icc &&
!memcmp(data + 1, "ICCRGBG1012", 11);
if (is_xmp || is_icc) {
const char* const fourccs[2] = { "XMP " , "ICCP" };
const char* const features[2] = { "XMP" , "ICC" };
WebPData metadata = { NULL, 0 };
// Construct metadata from sub-blocks.
// Usual case (including ICC profile): In each sub-block, the
// first byte specifies its size in bytes (0 to 255) and the
// rest of the bytes contain the data.
// Special case for XMP data: In each sub-block, the first byte
// is also part of the XMP payload. XMP in GIF also has a 257
// byte padding data. See the XMP specification for details.
while (1) {
WebPData prev_metadata = metadata;
WebPData subblock;
if (DGifGetExtensionNext(gif, &data) == GIF_ERROR) {
WebPDataClear(&metadata);
goto End;
}
if (data == NULL) break; // Finished.
subblock.size = is_xmp ? data[0] + 1 : data[0];
assert(subblock.size > 0);
subblock.bytes = is_xmp ? data : data + 1;
metadata.bytes =
(uint8_t*)realloc((void*)metadata.bytes,
prev_metadata.size + subblock.size);
if (metadata.bytes == NULL) {
WebPDataClear(&prev_metadata);
goto End;
}
metadata.size += subblock.size;
memcpy((void*)(metadata.bytes + prev_metadata.size),
subblock.bytes, subblock.size);
}
if (is_xmp) {
// XMP padding data is 0x01, 0xff, 0xfe ... 0x01, 0x00.
const size_t xmp_pading_size = 257;
if (metadata.size > xmp_pading_size) {
metadata.size -= xmp_pading_size;
}
}
// Add metadata chunk.
err = WebPMuxSetChunk(mux, fourccs[is_icc], &metadata, 1);
if (verbose) {
fprintf(stderr, "%s size: %d\n",
features[is_icc], (int)metadata.size);
}
WebPDataClear(&metadata);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not set %s chunk.\n",
ErrorString(err), features[is_icc]);
goto End;
}
if (is_icc) {
stored_icc = 1;
} else if (is_xmp) {
stored_xmp = 1;
}
}
}
break;
}
default: {
break; // skip
}
}
while (data != NULL) {
if (DGifGetExtensionNext(gif, &data) == GIF_ERROR) goto End;
}
break;
}
case TERMINATE_RECORD_TYPE: {
done = 1;
break;
}
default: {
if (verbose) {
fprintf(stderr, "Skipping over unknown record type %d\n", type);
}
break;
}
}
} while (!done);
// Flush any pending frames.
err = WebPFrameCacheFlushAll(cache, verbose, mux);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not add animation frame.\n",
ErrorString(err));
goto End;
}
// Finish muxing
err = WebPMuxSetAnimationParams(mux, &anim);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s): Could not set animation parameters.\n",
ErrorString(err));
goto End;
}
err = WebPMuxAssemble(mux, &webp_data);
if (err != WEBP_MUX_OK) {
fprintf(stderr, "ERROR (%s) assembling the WebP file.\n", ErrorString(err));
goto End;
}
if (out_file != NULL) {
if (!ExUtilWriteFile(out_file, webp_data.bytes, webp_data.size)) {
fprintf(stderr, "Error writing output file: %s\n", out_file);
goto End;
}
if (!quiet) {
fprintf(stderr, "Saved output file: %s\n", out_file);
}
} else {
if (!quiet) {
fprintf(stderr, "Nothing written; use -o flag to save the result.\n");
}
}
// All OK.
ok = 1;
gif_error = GIF_OK;
End:
WebPDataClear(&webp_data);
WebPMuxDelete(mux);
WebPPictureFree(&frame);
WebPFrameCacheDelete(cache);
if (out != NULL && out_file != NULL) fclose(out);
if (gif_error != GIF_OK) {
DisplayGifError(gif, gif_error);
}
if (gif != NULL) {
#if LOCAL_GIF_PREREQ(5,1)
DGifCloseFile(gif, &gif_error);
#else
DGifCloseFile(gif);
#endif
}
return !ok;
}
#else // !WEBP_HAVE_GIF
int main(int argc, const char *argv[]) {
fprintf(stderr, "GIF support not enabled in %s.\n", argv[0]);
(void)argc;
return 0;
}
#endif
//------------------------------------------------------------------------------