aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/gif.c
blob: d9c99d52cfdd924a9bb03178d29177388ca2d74d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
/*
 * Copyright (c) 2000 Fabrice Bellard
 * Copyright (c) 2002 Francois Revol
 * Copyright (c) 2006 Baptiste Coudurier
 *
 * first version by Francois Revol <revol@free.fr>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * GIF encoder
 * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt
 */

#define BITSTREAM_WRITER_LE
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "lzw.h"
#include "gif.h"

#include "put_bits.h"

typedef struct GIFContext {
    const AVClass *class;
    LZWState *lzw;
    uint8_t *buf;
    int buf_size;
    AVFrame *last_frame;
    int flags;
    uint32_t palette[AVPALETTE_COUNT];  ///< local reference palette for !pal8
    int palette_loaded;
    int transparent_index;
    uint8_t *pal_exdata;
    uint8_t *tmpl;                      ///< temporary line buffer
} GIFContext;

enum {
    GF_OFFSETTING = 1<<0,
    GF_TRANSDIFF  = 1<<1,
};

static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
{
    int histogram[AVPALETTE_COUNT] = {0};
    int x, y, i;

    for (y = 0; y < h; y++) {
        for (x = 0; x < w; x++)
            histogram[buf[x]]++;
        buf += linesize;
    }
    for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
        if (!histogram[i])
            return i;
    return -1;
}

static int gif_image_write_image(AVCodecContext *avctx,
                                 uint8_t **bytestream, uint8_t *end,
                                 const uint32_t *palette,
                                 const uint8_t *buf, const int linesize,
                                 AVPacket *pkt)
{
    GIFContext *s = avctx->priv_data;
    int len = 0, height = avctx->height, width = avctx->width, x, y;
    int x_start = 0, y_start = 0, trans = s->transparent_index;
    int honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette;
    const uint8_t *ptr;

    /* Crop image */
    if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {
        const uint8_t *ref = s->last_frame->data[0];
        const int ref_linesize = s->last_frame->linesize[0];
        int x_end = avctx->width  - 1,
            y_end = avctx->height - 1;

        /* skip common lines */
        while (y_start < y_end) {
            if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
                break;
            y_start++;
        }
        while (y_end > y_start) {
            if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
                break;
            y_end--;
        }
        height = y_end + 1 - y_start;

        /* skip common columns */
        while (x_start < x_end) {
            int same_column = 1;
            for (y = y_start; y <= y_end; y++) {
                if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
                    same_column = 0;
                    break;
                }
            }
            if (!same_column)
                break;
            x_start++;
        }
        while (x_end > x_start) {
            int same_column = 1;
            for (y = y_start; y <= y_end; y++) {
                if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
                    same_column = 0;
                    break;
                }
            }
            if (!same_column)
                break;
            x_end--;
        }
        width = x_end + 1 - x_start;

        av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
               width, height, x_start, y_start, avctx->width, avctx->height);
    }

    /* image block */
    bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
    bytestream_put_le16(bytestream, x_start);
    bytestream_put_le16(bytestream, y_start);
    bytestream_put_le16(bytestream, width);
    bytestream_put_le16(bytestream, height);

    if (!palette) {
        bytestream_put_byte(bytestream, 0x00); /* flags */
    } else {
        unsigned i;
        bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
        for (i = 0; i < AVPALETTE_COUNT; i++) {
            const uint32_t v = palette[i];
            bytestream_put_be24(bytestream, v);
        }
    }

    if (honor_transparency && trans < 0) {
        trans = pick_palette_entry(buf + y_start*linesize + x_start,
                                   linesize, width, height);
        if (trans < 0) { // TODO, patch welcome
            av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
        } else {
            uint8_t *pal_exdata = s->pal_exdata;
            if (!pal_exdata)
                pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
            if (!pal_exdata)
                return AVERROR(ENOMEM);
            memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
            pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
        }
    }
    if (trans < 0)
        honor_transparency = 0;

    bytestream_put_byte(bytestream, 0x08);

    ff_lzw_encode_init(s->lzw, s->buf, s->buf_size,
                       12, FF_LZW_GIF, put_bits);

    ptr = buf + y_start*linesize + x_start;
    if (honor_transparency) {
        const int ref_linesize = s->last_frame->linesize[0];
        const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;

        for (y = 0; y < height; y++) {
            memcpy(s->tmpl, ptr, width);
            for (x = 0; x < width; x++)
                if (ref[x] == ptr[x])
                    s->tmpl[x] = trans;
            len += ff_lzw_encode(s->lzw, s->tmpl, width);
            ptr += linesize;
            ref += ref_linesize;
        }
    } else {
        for (y = 0; y < height; y++) {
            len += ff_lzw_encode(s->lzw, ptr, width);
            ptr += linesize;
        }
    }
    len += ff_lzw_encode_flush(s->lzw, flush_put_bits);

    ptr = s->buf;
    while (len > 0) {
        int size = FFMIN(255, len);
        bytestream_put_byte(bytestream, size);
        if (end - *bytestream < size)
            return -1;
        bytestream_put_buffer(bytestream, ptr, size);
        ptr += size;
        len -= size;
    }
    bytestream_put_byte(bytestream, 0x00); /* end of image block */
    return 0;
}

static av_cold int gif_encode_init(AVCodecContext *avctx)
{
    GIFContext *s = avctx->priv_data;

    if (avctx->width > 65535 || avctx->height > 65535) {
        av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
        return AVERROR(EINVAL);
    }
#if FF_API_CODED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
    avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
    avctx->coded_frame->key_frame = 1;
FF_ENABLE_DEPRECATION_WARNINGS
#endif

    s->transparent_index = -1;

    s->lzw = av_mallocz(ff_lzw_encode_state_size);
    s->buf_size = avctx->width*avctx->height*2 + 1000;
    s->buf = av_malloc(s->buf_size);
    s->tmpl = av_malloc(avctx->width);
    if (!s->tmpl || !s->buf || !s->lzw)
        return AVERROR(ENOMEM);

    if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
        av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);

    return 0;
}

/* FIXME: duplicated with lavc */
static int get_palette_transparency_index(const uint32_t *palette)
{
    int transparent_color_index = -1;
    unsigned i, smallest_alpha = 0xff;

    if (!palette)
        return -1;

    for (i = 0; i < AVPALETTE_COUNT; i++) {
        const uint32_t v = palette[i];
        if (v >> 24 < smallest_alpha) {
            smallest_alpha = v >> 24;
            transparent_color_index = i;
        }
    }
    return smallest_alpha < 128 ? transparent_color_index : -1;
}

static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                            const AVFrame *pict, int *got_packet)
{
    GIFContext *s = avctx->priv_data;
    uint8_t *outbuf_ptr, *end;
    const uint32_t *palette = NULL;
    int ret;

    if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)
        return ret;
    outbuf_ptr = pkt->data;
    end        = pkt->data + pkt->size;

    if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
        uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
        if (!pal_exdata)
            return AVERROR(ENOMEM);
        memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
        palette = (uint32_t*)pict->data[1];

        s->pal_exdata = pal_exdata;

        /* The first palette with PAL8 will be used as generic palette by the
         * muxer so we don't need to write it locally in the packet. We store
         * it as a reference here in case it changes later. */
        if (!s->palette_loaded) {
            memcpy(s->palette, palette, AVPALETTE_SIZE);
            s->transparent_index = get_palette_transparency_index(palette);
            s->palette_loaded = 1;
            palette = NULL;
        } else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
            palette = NULL;
        }
    }

    gif_image_write_image(avctx, &outbuf_ptr, end, palette,
                          pict->data[0], pict->linesize[0], pkt);
    if (!s->last_frame) {
        s->last_frame = av_frame_alloc();
        if (!s->last_frame)
            return AVERROR(ENOMEM);
    }
    av_frame_unref(s->last_frame);
    ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
    if (ret < 0)
        return ret;

    pkt->size   = outbuf_ptr - pkt->data;
    pkt->flags |= AV_PKT_FLAG_KEY;
    *got_packet = 1;

    return 0;
}

static int gif_encode_close(AVCodecContext *avctx)
{
    GIFContext *s = avctx->priv_data;

    av_freep(&s->lzw);
    av_freep(&s->buf);
    s->buf_size = 0;
    av_frame_free(&s->last_frame);
    av_freep(&s->tmpl);
    return 0;
}

#define OFFSET(x) offsetof(GIFContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
static const AVOption gif_options[] = {
    { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
        { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
        { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
    { NULL }
};

static const AVClass gif_class = {
    .class_name = "GIF encoder",
    .item_name  = av_default_item_name,
    .option     = gif_options,
    .version    = LIBAVUTIL_VERSION_INT,
};

AVCodec ff_gif_encoder = {
    .name           = "gif",
    .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_GIF,
    .priv_data_size = sizeof(GIFContext),
    .init           = gif_encode_init,
    .encode2        = gif_encode_frame,
    .close          = gif_encode_close,
    .pix_fmts       = (const enum AVPixelFormat[]){
        AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
        AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
    },
    .priv_class     = &gif_class,
};