2 * Copyright (c) 2000 Fabrice Bellard
3 * Copyright (c) 2002 Francois Revol
4 * Copyright (c) 2006 Baptiste Coudurier
6 * first version by Francois Revol <revol@free.fr>
8 * This file is part of FFmpeg.
10 * FFmpeg is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU Lesser General Public
12 * License as published by the Free Software Foundation; either
13 * version 2.1 of the License, or (at your option) any later version.
15 * FFmpeg is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with FFmpeg; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
31 #define BITSTREAM_WRITER_LE
32 #include "libavutil/opt.h"
33 #include "libavutil/imgutils.h"
35 #include "bytestream.h"
42 typedef struct GIFContext {
49 uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
51 int transparent_index;
53 uint8_t *tmpl; ///< temporary line buffer
61 static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
63 int histogram[AVPALETTE_COUNT] = {0};
66 for (y = 0; y < h; y++) {
67 for (x = 0; x < w; x++)
71 for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
77 static int gif_image_write_image(AVCodecContext *avctx,
78 uint8_t **bytestream, uint8_t *end,
79 const uint32_t *palette,
80 const uint8_t *buf, const int linesize,
83 GIFContext *s = avctx->priv_data;
84 int len = 0, height = avctx->height, width = avctx->width, x, y;
85 int x_start = 0, y_start = 0, trans = s->transparent_index;
86 int honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette;
90 if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {
91 const uint8_t *ref = s->last_frame->data[0];
92 const int ref_linesize = s->last_frame->linesize[0];
93 int x_end = avctx->width - 1,
94 y_end = avctx->height - 1;
96 /* skip common lines */
97 while (y_start < y_end) {
98 if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
102 while (y_end > y_start) {
103 if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
107 height = y_end + 1 - y_start;
109 /* skip common columns */
110 while (x_start < x_end) {
112 for (y = y_start; y <= y_end; y++) {
113 if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
122 while (x_end > x_start) {
124 for (y = y_start; y <= y_end; y++) {
125 if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
134 width = x_end + 1 - x_start;
136 av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
137 width, height, x_start, y_start, avctx->width, avctx->height);
141 bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
142 bytestream_put_le16(bytestream, x_start);
143 bytestream_put_le16(bytestream, y_start);
144 bytestream_put_le16(bytestream, width);
145 bytestream_put_le16(bytestream, height);
148 bytestream_put_byte(bytestream, 0x00); /* flags */
151 bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
152 for (i = 0; i < AVPALETTE_COUNT; i++) {
153 const uint32_t v = palette[i];
154 bytestream_put_be24(bytestream, v);
158 if (honor_transparency && trans < 0) {
159 trans = pick_palette_entry(buf + y_start*linesize + x_start,
160 linesize, width, height);
161 if (trans < 0) { // TODO, patch welcome
162 av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
164 uint8_t *pal_exdata = s->pal_exdata;
166 pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
168 return AVERROR(ENOMEM);
169 memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
170 pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
174 honor_transparency = 0;
176 bytestream_put_byte(bytestream, 0x08);
178 ff_lzw_encode_init(s->lzw, s->buf, s->buf_size,
179 12, FF_LZW_GIF, put_bits);
181 ptr = buf + y_start*linesize + x_start;
182 if (honor_transparency) {
183 const int ref_linesize = s->last_frame->linesize[0];
184 const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;
186 for (y = 0; y < height; y++) {
187 memcpy(s->tmpl, ptr, width);
188 for (x = 0; x < width; x++)
189 if (ref[x] == ptr[x])
191 len += ff_lzw_encode(s->lzw, s->tmpl, width);
196 for (y = 0; y < height; y++) {
197 len += ff_lzw_encode(s->lzw, ptr, width);
201 len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
205 int size = FFMIN(255, len);
206 bytestream_put_byte(bytestream, size);
207 if (end - *bytestream < size)
209 bytestream_put_buffer(bytestream, ptr, size);
213 bytestream_put_byte(bytestream, 0x00); /* end of image block */
217 static av_cold int gif_encode_init(AVCodecContext *avctx)
219 GIFContext *s = avctx->priv_data;
221 if (avctx->width > 65535 || avctx->height > 65535) {
222 av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
223 return AVERROR(EINVAL);
225 #if FF_API_CODED_FRAME
226 FF_DISABLE_DEPRECATION_WARNINGS
227 avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
228 avctx->coded_frame->key_frame = 1;
229 FF_ENABLE_DEPRECATION_WARNINGS
232 s->transparent_index = -1;
234 s->lzw = av_mallocz(ff_lzw_encode_state_size);
235 s->buf_size = avctx->width*avctx->height*2 + 1000;
236 s->buf = av_malloc(s->buf_size);
237 s->tmpl = av_malloc(avctx->width);
238 if (!s->tmpl || !s->buf || !s->lzw)
239 return AVERROR(ENOMEM);
241 if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
242 av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
247 /* FIXME: duplicated with lavc */
248 static int get_palette_transparency_index(const uint32_t *palette)
250 int transparent_color_index = -1;
251 unsigned i, smallest_alpha = 0xff;
256 for (i = 0; i < AVPALETTE_COUNT; i++) {
257 const uint32_t v = palette[i];
258 if (v >> 24 < smallest_alpha) {
259 smallest_alpha = v >> 24;
260 transparent_color_index = i;
263 return smallest_alpha < 128 ? transparent_color_index : -1;
266 static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
267 const AVFrame *pict, int *got_packet)
269 GIFContext *s = avctx->priv_data;
270 uint8_t *outbuf_ptr, *end;
271 const uint32_t *palette = NULL;
274 if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)
276 outbuf_ptr = pkt->data;
277 end = pkt->data + pkt->size;
279 if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
280 uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
282 return AVERROR(ENOMEM);
283 memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
284 palette = (uint32_t*)pict->data[1];
286 s->pal_exdata = pal_exdata;
288 /* The first palette with PAL8 will be used as generic palette by the
289 * muxer so we don't need to write it locally in the packet. We store
290 * it as a reference here in case it changes later. */
291 if (!s->palette_loaded) {
292 memcpy(s->palette, palette, AVPALETTE_SIZE);
293 s->transparent_index = get_palette_transparency_index(palette);
294 s->palette_loaded = 1;
296 } else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
301 gif_image_write_image(avctx, &outbuf_ptr, end, palette,
302 pict->data[0], pict->linesize[0], pkt);
303 if (!s->last_frame) {
304 s->last_frame = av_frame_alloc();
306 return AVERROR(ENOMEM);
308 av_frame_unref(s->last_frame);
309 ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
313 pkt->size = outbuf_ptr - pkt->data;
314 pkt->flags |= AV_PKT_FLAG_KEY;
320 static int gif_encode_close(AVCodecContext *avctx)
322 GIFContext *s = avctx->priv_data;
327 av_frame_free(&s->last_frame);
332 #define OFFSET(x) offsetof(GIFContext, x)
333 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
334 static const AVOption gif_options[] = {
335 { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
336 { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
337 { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
341 static const AVClass gif_class = {
342 .class_name = "GIF encoder",
343 .item_name = av_default_item_name,
344 .option = gif_options,
345 .version = LIBAVUTIL_VERSION_INT,
348 AVCodec ff_gif_encoder = {
350 .long_name = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
351 .type = AVMEDIA_TYPE_VIDEO,
352 .id = AV_CODEC_ID_GIF,
353 .priv_data_size = sizeof(GIFContext),
354 .init = gif_encode_init,
355 .encode2 = gif_encode_frame,
356 .close = gif_encode_close,
357 .pix_fmts = (const enum AVPixelFormat[]){
358 AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
359 AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
361 .priv_class = &gif_class,