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 {
43    const AVClass *class;
44    LZWState *lzw;
45    uint8_t *buf;
46    AVFrame *last_frame;
47    int flags;
48    uint32_t palette[AVPALETTE_COUNT];  ///< local reference palette for !pal8
49    uint8_t *tmpl;                      ///< temporary line buffer
50} GIFContext;
51
52enum {
53    GF_OFFSETTING = 1<<0,
54    GF_TRANSDIFF  = 1<<1,
55};
56
57static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
58{
59    int histogram[AVPALETTE_COUNT] = {0};
60    int x, y, i;
61
62    for (y = 0; y < h; y++) {
63        for (x = 0; x < w; x++)
64            histogram[buf[x]]++;
65        buf += linesize;
66    }
67    for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
68        if (!histogram[i])
69            return i;
70    return -1;
71}
72
73static int gif_image_write_image(AVCodecContext *avctx,
74                                 uint8_t **bytestream, uint8_t *end,
75                                 const uint32_t *palette,
76                                 const uint8_t *buf, const int linesize,
77                                 AVPacket *pkt)
78{
79    GIFContext *s = avctx->priv_data;
80    int len = 0, height = avctx->height, width = avctx->width, x, y;
81    int x_start = 0, y_start = 0, trans = -1;
82    const uint8_t *ptr;
83
84    /* Crop image */
85    // TODO support with palette change
86    if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {
87        const uint8_t *ref = s->last_frame->data[0];
88        const int ref_linesize = s->last_frame->linesize[0];
89        int x_end = avctx->width  - 1,
90            y_end = avctx->height - 1;
91
92        /* skip common lines */
93        while (y_start < y_end) {
94            if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
95                break;
96            y_start++;
97        }
98        while (y_end > y_start) {
99            if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
100                break;
101            y_end--;
102        }
103        height = y_end + 1 - y_start;
104
105        /* skip common columns */
106        while (x_start < x_end) {
107            int same_column = 1;
108            for (y = y_start; y < y_end; y++) {
109                if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
110                    same_column = 0;
111                    break;
112                }
113            }
114            if (!same_column)
115                break;
116            x_start++;
117        }
118        while (x_end > x_start) {
119            int same_column = 1;
120            for (y = y_start; y < y_end; y++) {
121                if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
122                    same_column = 0;
123                    break;
124                }
125            }
126            if (!same_column)
127                break;
128            x_end--;
129        }
130        width = x_end + 1 - x_start;
131
132        av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
133               width, height, x_start, y_start, avctx->width, avctx->height);
134    }
135
136    /* image block */
137    bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);
138    bytestream_put_le16(bytestream, x_start);
139    bytestream_put_le16(bytestream, y_start);
140    bytestream_put_le16(bytestream, width);
141    bytestream_put_le16(bytestream, height);
142
143    if (!palette) {
144        bytestream_put_byte(bytestream, 0x00); /* flags */
145    } else {
146        unsigned i;
147        bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
148        for (i = 0; i < AVPALETTE_COUNT; i++) {
149            const uint32_t v = palette[i];
150            bytestream_put_be24(bytestream, v);
151        }
152    }
153
154    /* TODO: support with palette change (pal8) */
155    if ((s->flags & GF_TRANSDIFF) && s->last_frame && !palette) {
156        trans = pick_palette_entry(buf + y_start*linesize + x_start,
157                                   linesize, width, height);
158        if (trans < 0) { // TODO, patch welcome
159            av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
160        } else {
161            uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
162            if (!pal_exdata)
163                return AVERROR(ENOMEM);
164            memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);
165            pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;
166        }
167    }
168
169    bytestream_put_byte(bytestream, 0x08);
170
171    ff_lzw_encode_init(s->lzw, s->buf, 2 * width * height,
172                       12, FF_LZW_GIF, put_bits);
173
174    ptr = buf + y_start*linesize + x_start;
175    if (trans >= 0) {
176        const int ref_linesize = s->last_frame->linesize[0];
177        const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;
178
179        for (y = 0; y < height; y++) {
180            memcpy(s->tmpl, ptr, width);
181            for (x = 0; x < width; x++)
182                if (ref[x] == ptr[x])
183                    s->tmpl[x] = trans;
184            len += ff_lzw_encode(s->lzw, s->tmpl, width);
185            ptr += linesize;
186            ref += ref_linesize;
187        }
188    } else {
189        for (y = 0; y < height; y++) {
190            len += ff_lzw_encode(s->lzw, ptr, width);
191            ptr += linesize;
192        }
193    }
194    len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
195
196    ptr = s->buf;
197    while (len > 0) {
198        int size = FFMIN(255, len);
199        bytestream_put_byte(bytestream, size);
200        if (end - *bytestream < size)
201            return -1;
202        bytestream_put_buffer(bytestream, ptr, size);
203        ptr += size;
204        len -= size;
205    }
206    bytestream_put_byte(bytestream, 0x00); /* end of image block */
207    return 0;
208}
209
210static av_cold int gif_encode_init(AVCodecContext *avctx)
211{
212    GIFContext *s = avctx->priv_data;
213
214    if (avctx->width > 65535 || avctx->height > 65535) {
215        av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");
216        return AVERROR(EINVAL);
217    }
218
219    avctx->coded_frame = av_frame_alloc();
220    if (!avctx->coded_frame)
221        return AVERROR(ENOMEM);
222
223    avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
224    avctx->coded_frame->key_frame = 1;
225
226    s->lzw = av_mallocz(ff_lzw_encode_state_size);
227    s->buf = av_malloc(avctx->width*avctx->height*2);
228    s->tmpl = av_malloc(avctx->width);
229    if (!s->tmpl || !s->buf || !s->lzw)
230        return AVERROR(ENOMEM);
231
232    if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
233        av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
234
235    return 0;
236}
237
238static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
239                            const AVFrame *pict, int *got_packet)
240{
241    GIFContext *s = avctx->priv_data;
242    uint8_t *outbuf_ptr, *end;
243    const uint32_t *palette = NULL;
244    int ret;
245
246    if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0)
247        return ret;
248    outbuf_ptr = pkt->data;
249    end        = pkt->data + pkt->size;
250
251    if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
252        uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
253        if (!pal_exdata)
254            return AVERROR(ENOMEM);
255        memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
256        palette = (uint32_t*)pict->data[1];
257    }
258
259    gif_image_write_image(avctx, &outbuf_ptr, end, palette,
260                          pict->data[0], pict->linesize[0], pkt);
261    if (!s->last_frame) {
262        s->last_frame = av_frame_alloc();
263        if (!s->last_frame)
264            return AVERROR(ENOMEM);
265    }
266    av_frame_unref(s->last_frame);
267    ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
268    if (ret < 0)
269        return ret;
270
271    pkt->size   = outbuf_ptr - pkt->data;
272    pkt->flags |= AV_PKT_FLAG_KEY;
273    *got_packet = 1;
274
275    return 0;
276}
277
278static int gif_encode_close(AVCodecContext *avctx)
279{
280    GIFContext *s = avctx->priv_data;
281
282    av_frame_free(&avctx->coded_frame);
283
284    av_freep(&s->lzw);
285    av_freep(&s->buf);
286    av_frame_free(&s->last_frame);
287    av_freep(&s->tmpl);
288    return 0;
289}
290
291#define OFFSET(x) offsetof(GIFContext, x)
292#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
293static const AVOption gif_options[] = {
294    { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },
295        { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },
296        { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },
297    { NULL }
298};
299
300static const AVClass gif_class = {
301    .class_name = "GIF encoder",
302    .item_name  = av_default_item_name,
303    .option     = gif_options,
304    .version    = LIBAVUTIL_VERSION_INT,
305};
306
307AVCodec ff_gif_encoder = {
308    .name           = "gif",
309    .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),
310    .type           = AVMEDIA_TYPE_VIDEO,
311    .id             = AV_CODEC_ID_GIF,
312    .priv_data_size = sizeof(GIFContext),
313    .init           = gif_encode_init,
314    .encode2        = gif_encode_frame,
315    .close          = gif_encode_close,
316    .pix_fmts       = (const enum AVPixelFormat[]){
317        AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
318        AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE
319    },
320    .priv_class     = &gif_class,
321};
322