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1/*
2 * Copyright (c) 2000 Fabrice Bellard
3 * Copyright (c) 2002 Francois Revol
4 * Copyright (c) 2006 Baptiste Coudurier
5 *
6 * first version by Francois Revol <revol@free.fr>
7 *
8 * This file is part of FFmpeg.
9 *
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.
14 *
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.
19 *
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
23 */
24
25/**
26 * @file
27 * GIF encoder
28 * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
29 */
30
31#define BITSTREAM_WRITER_LE
32#include "libavutil/opt.h"
33#include "libavutil/imgutils.h"
34#include "avcodec.h"
35#include "bytestream.h"
36#include "internal.h"
37#include "lzw.h"
38#include "gif.h"
39
40#include "put_bits.h"
41
42typedef struct GIFContext {
43 const AVClass *class;
44 LZWState *lzw;
45 uint8_t *buf;
46 int buf_size;
47 AVFrame *last_frame;
48 int flags;
49 uint32_t palette[AVPALETTE_COUNT]; ///< local reference palette for !pal8
50 int palette_loaded;
51 int transparent_index;
52 uint8_t *pal_exdata;
53 uint8_t *tmpl; ///< temporary line buffer
54} GIFContext;
55
56enum {
57 GF_OFFSETTING = 1<<0,
58 GF_TRANSDIFF = 1<<1,
59};
60
61static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
62{
63 int histogram[AVPALETTE_COUNT] = {0};
64 int x, y, i;
65
66 for (y = 0; y < h; y++) {
67 for (x = 0; x < w; x++)
68 histogram[buf[x]]++;
69 buf += linesize;
70 }
71 for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
72 if (!histogram[i])
73 return i;
74 return -1;
75}
76
77static 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,
81 AVPacket *pkt)
82{
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;
87 const uint8_t *ptr;
88
89 /* Crop image */
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;
95
96 /* skip common lines */
97 while (y_start < y_end) {
98 if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
99 break;
100 y_start++;
101 }
102 while (y_end > y_start) {
103 if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
104 break;
105 y_end--;
106 }
107 height = y_end + 1 - y_start;
108
109 /* skip common columns */
110 while (x_start < x_end) {
111 int same_column = 1;
112 for (y = y_start; y <= y_end; y++) {
113 if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
114 same_column = 0;
115 break;
116 }
117 }
118 if (!same_column)
119 break;
120 x_start++;
121 }
122 while (x_end > x_start) {
123 int same_column = 1;
124 for (y = y_start; y <= y_end; y++) {
125 if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
126 same_column = 0;
127 break;
128 }
129 }
130 if (!same_column)
131 break;
132 x_end--;
133 }
134 width = x_end + 1 - x_start;
135
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);
138 }
139
140 /* image block */
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);
146
147 if (!palette) {
148 bytestream_put_byte(bytestream, 0x00); /* flags */
149 } else {
150 unsigned i;
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);
155 }
156 }
157
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");
163 } else {
164 uint8_t *pal_exdata = s->pal_exdata;
165 if (!pal_exdata)
166 pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
167 if (!pal_exdata)
168 return AVERROR(ENOMEM);
169 memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
170 pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
171 }
172 }
173 if (trans < 0)
174 honor_transparency = 0;
175
176 bytestream_put_byte(bytestream, 0x08);
177
178 ff_lzw_encode_init(s->lzw, s->buf, s->buf_size,
179 12, FF_LZW_GIF, put_bits);
180
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;
185
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])
190 s->tmpl[x] = trans;
191 len += ff_lzw_encode(s->lzw, s->tmpl, width);
192 ptr += linesize;
193 ref += ref_linesize;
194 }
195 } else {
196 for (y = 0; y < height; y++) {
197 len += ff_lzw_encode(s->lzw, ptr, width);
198 ptr += linesize;
199 }
200 }
201 len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
202
203 ptr = s->buf;
204 while (len > 0) {
205 int size = FFMIN(255, len);
206 bytestream_put_byte(bytestream, size);
207 if (end - *bytestream < size)
208 return -1;
209 bytestream_put_buffer(bytestream, ptr, size);
210 ptr += size;
211 len -= size;
212 }
213 bytestream_put_byte(bytestream, 0x00); /* end of image block */
214 return 0;
215}
216
217static av_cold int gif_encode_init(AVCodecContext *avctx)
218{
219 GIFContext *s = avctx->priv_data;
220
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);
224 }
225#if FF_API_CODED_FRAME
226FF_DISABLE_DEPRECATION_WARNINGS
227 avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
228 avctx->coded_frame->key_frame = 1;
229FF_ENABLE_DEPRECATION_WARNINGS
230#endif
231
232 s->transparent_index = -1;
233
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);
240
241 if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
242 av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
243
244 return 0;
245}
246
247/* FIXME: duplicated with lavc */
248static int get_palette_transparency_index(const uint32_t *palette)
249{
250 int transparent_color_index = -1;
251 unsigned i, smallest_alpha = 0xff;
252
253 if (!palette)
254 return -1;
255
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;
261 }
262 }
263 return smallest_alpha < 128 ? transparent_color_index : -1;
264}
265
266static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
267 const AVFrame *pict, int *got_packet)
268{
269 GIFContext *s = avctx->priv_data;
270 uint8_t *outbuf_ptr, *end;
271 const uint32_t *palette = NULL;
272 int ret;
273
274 if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)
275 return ret;
276 outbuf_ptr = pkt->data;
277 end = pkt->data + pkt->size;
278
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);
281 if (!pal_exdata)
282 return AVERROR(ENOMEM);
283 memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
284 palette = (uint32_t*)pict->data[1];
285
286 s->pal_exdata = pal_exdata;
287
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;
295 palette = NULL;
296 } else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
297 palette = NULL;
298 }
299 }
300
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();
305 if (!s->last_frame)
306 return AVERROR(ENOMEM);
307 }
308 av_frame_unref(s->last_frame);
309 ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
310 if (ret < 0)
311 return ret;
312
313 pkt->size = outbuf_ptr - pkt->data;
314 pkt->flags |= AV_PKT_FLAG_KEY;
315 *got_packet = 1;
316
317 return 0;
318}
319
320static int gif_encode_close(AVCodecContext *avctx)
321{
322 GIFContext *s = avctx->priv_data;
323
324 av_freep(&s->lzw);
325 av_freep(&s->buf);
326 s->buf_size = 0;
327 av_frame_free(&s->last_frame);
328 av_freep(&s->tmpl);
329 return 0;
330}
331
332#define OFFSET(x) offsetof(GIFContext, x)
333#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
334static 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" },
338 { NULL }
339};
340
341static 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,
346};
347
348AVCodec ff_gif_encoder = {
349 .name = "gif",
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
360 },
361 .priv_class = &gif_class,
362};
363
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