1/*
2 * DVD subtitle decoding
3 * Copyright (c) 2005 Fabrice Bellard
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "avcodec.h"
23#include "get_bits.h"
24#include "internal.h"
25
26#include "libavutil/attributes.h"
27#include "libavutil/colorspace.h"
28#include "libavutil/opt.h"
29#include "libavutil/imgutils.h"
30#include "libavutil/avstring.h"
31
32typedef struct DVDSubContext
33{
34  AVClass *class;
35  uint32_t palette[16];
36  char    *palette_str;
37  int      has_palette;
38  uint8_t  colormap[4];
39  uint8_t  alpha[256];
40  uint8_t *buf;
41  int      buf_size;
42#ifdef DEBUG
43  int sub_id;
44#endif
45} DVDSubContext;
46
47static void yuv_a_to_rgba(const uint8_t *ycbcr, const uint8_t *alpha, uint32_t *rgba, int num_values)
48{
49    const uint8_t *cm = ff_crop_tab + MAX_NEG_CROP;
50    uint8_t r, g, b;
51    int i, y, cb, cr;
52    int r_add, g_add, b_add;
53
54    for (i = num_values; i > 0; i--) {
55        y = *ycbcr++;
56        cr = *ycbcr++;
57        cb = *ycbcr++;
58        YUV_TO_RGB1_CCIR(cb, cr);
59        YUV_TO_RGB2_CCIR(r, g, b, y);
60        *rgba++ = (*alpha++ << 24) | (r << 16) | (g << 8) | b;
61    }
62}
63
64static int decode_run_2bit(GetBitContext *gb, int *color)
65{
66    unsigned int v, t;
67
68    v = 0;
69    for (t = 1; v < t && t <= 0x40; t <<= 2)
70        v = (v << 4) | get_bits(gb, 4);
71    *color = v & 3;
72    if (v < 4) { /* Code for fill rest of line */
73        return INT_MAX;
74    }
75    return v >> 2;
76}
77
78static int decode_run_8bit(GetBitContext *gb, int *color)
79{
80    int len;
81    int has_run = get_bits1(gb);
82    if (get_bits1(gb))
83        *color = get_bits(gb, 8);
84    else
85        *color = get_bits(gb, 2);
86    if (has_run) {
87        if (get_bits1(gb)) {
88            len = get_bits(gb, 7);
89            if (len == 0)
90                len = INT_MAX;
91            else
92                len += 9;
93        } else
94            len = get_bits(gb, 3) + 2;
95    } else
96        len = 1;
97    return len;
98}
99
100static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
101                      const uint8_t *buf, int start, int buf_size, int is_8bit)
102{
103    GetBitContext gb;
104    int bit_len;
105    int x, y, len, color;
106    uint8_t *d;
107
108    bit_len = (buf_size - start) * 8;
109    init_get_bits(&gb, buf + start, bit_len);
110
111    x = 0;
112    y = 0;
113    d = bitmap;
114    for(;;) {
115        if (get_bits_count(&gb) > bit_len)
116            return -1;
117        if (is_8bit)
118            len = decode_run_8bit(&gb, &color);
119        else
120            len = decode_run_2bit(&gb, &color);
121        len = FFMIN(len, w - x);
122        memset(d + x, color, len);
123        x += len;
124        if (x >= w) {
125            y++;
126            if (y >= h)
127                break;
128            d += linesize;
129            x = 0;
130            /* byte align */
131            align_get_bits(&gb);
132        }
133    }
134    return 0;
135}
136
137static void guess_palette(DVDSubContext* ctx,
138                          uint32_t *rgba_palette,
139                          uint32_t subtitle_color)
140{
141    static const uint8_t level_map[4][4] = {
142        // this configuration (full range, lowest to highest) in tests
143        // seemed most common, so assume this
144        {0xff},
145        {0x00, 0xff},
146        {0x00, 0x80, 0xff},
147        {0x00, 0x55, 0xaa, 0xff},
148    };
149    uint8_t color_used[16] = { 0 };
150    int nb_opaque_colors, i, level, j, r, g, b;
151    uint8_t *colormap = ctx->colormap, *alpha = ctx->alpha;
152
153    if(ctx->has_palette) {
154        for(i = 0; i < 4; i++)
155            rgba_palette[i] = (ctx->palette[colormap[i]] & 0x00ffffff)
156                              | ((alpha[i] * 17U) << 24);
157        return;
158    }
159
160    for(i = 0; i < 4; i++)
161        rgba_palette[i] = 0;
162
163    nb_opaque_colors = 0;
164    for(i = 0; i < 4; i++) {
165        if (alpha[i] != 0 && !color_used[colormap[i]]) {
166            color_used[colormap[i]] = 1;
167            nb_opaque_colors++;
168        }
169    }
170
171    if (nb_opaque_colors == 0)
172        return;
173
174    j = 0;
175    memset(color_used, 0, 16);
176    for(i = 0; i < 4; i++) {
177        if (alpha[i] != 0) {
178            if (!color_used[colormap[i]])  {
179                level = level_map[nb_opaque_colors][j];
180                r = (((subtitle_color >> 16) & 0xff) * level) >> 8;
181                g = (((subtitle_color >> 8) & 0xff) * level) >> 8;
182                b = (((subtitle_color >> 0) & 0xff) * level) >> 8;
183                rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] * 17) << 24);
184                color_used[colormap[i]] = (i + 1);
185                j++;
186            } else {
187                rgba_palette[i] = (rgba_palette[color_used[colormap[i]] - 1] & 0x00ffffff) |
188                                    ((alpha[i] * 17) << 24);
189            }
190        }
191    }
192}
193
194static void reset_rects(AVSubtitle *sub_header)
195{
196    int i;
197
198    if (sub_header->rects != NULL) {
199        for (i = 0; i < sub_header->num_rects; i++) {
200            av_freep(&sub_header->rects[i]->pict.data[0]);
201            av_freep(&sub_header->rects[i]->pict.data[1]);
202            av_freep(&sub_header->rects[i]);
203        }
204        av_freep(&sub_header->rects);
205        sub_header->num_rects = 0;
206    }
207}
208
209#define READ_OFFSET(a) (big_offsets ? AV_RB32(a) : AV_RB16(a))
210
211static int decode_dvd_subtitles(DVDSubContext *ctx, AVSubtitle *sub_header,
212                                const uint8_t *buf, int buf_size)
213{
214    int cmd_pos, pos, cmd, x1, y1, x2, y2, offset1, offset2, next_cmd_pos;
215    int big_offsets, offset_size, is_8bit = 0;
216    const uint8_t *yuv_palette = 0;
217    uint8_t *colormap = ctx->colormap, *alpha = ctx->alpha;
218    int date;
219    int i;
220    int is_menu = 0;
221
222    if (buf_size < 10)
223        return -1;
224
225    if (AV_RB16(buf) == 0) {   /* HD subpicture with 4-byte offsets */
226        big_offsets = 1;
227        offset_size = 4;
228        cmd_pos = 6;
229    } else {
230        big_offsets = 0;
231        offset_size = 2;
232        cmd_pos = 2;
233    }
234
235    cmd_pos = READ_OFFSET(buf + cmd_pos);
236
237    if (cmd_pos < 0 || cmd_pos > buf_size - 2 - offset_size)
238        return AVERROR(EAGAIN);
239
240    while (cmd_pos > 0 && cmd_pos < buf_size - 2 - offset_size) {
241        date = AV_RB16(buf + cmd_pos);
242        next_cmd_pos = READ_OFFSET(buf + cmd_pos + 2);
243        av_dlog(NULL, "cmd_pos=0x%04x next=0x%04x date=%d\n",
244                cmd_pos, next_cmd_pos, date);
245        pos = cmd_pos + 2 + offset_size;
246        offset1 = -1;
247        offset2 = -1;
248        x1 = y1 = x2 = y2 = 0;
249        while (pos < buf_size) {
250            cmd = buf[pos++];
251            av_dlog(NULL, "cmd=%02x\n", cmd);
252            switch(cmd) {
253            case 0x00:
254                /* menu subpicture */
255                is_menu = 1;
256                break;
257            case 0x01:
258                /* set start date */
259                sub_header->start_display_time = (date << 10) / 90;
260                break;
261            case 0x02:
262                /* set end date */
263                sub_header->end_display_time = (date << 10) / 90;
264                break;
265            case 0x03:
266                /* set colormap */
267                if ((buf_size - pos) < 2)
268                    goto fail;
269                colormap[3] = buf[pos] >> 4;
270                colormap[2] = buf[pos] & 0x0f;
271                colormap[1] = buf[pos + 1] >> 4;
272                colormap[0] = buf[pos + 1] & 0x0f;
273                pos += 2;
274                break;
275            case 0x04:
276                /* set alpha */
277                if ((buf_size - pos) < 2)
278                    goto fail;
279                alpha[3] = buf[pos] >> 4;
280                alpha[2] = buf[pos] & 0x0f;
281                alpha[1] = buf[pos + 1] >> 4;
282                alpha[0] = buf[pos + 1] & 0x0f;
283                pos += 2;
284            av_dlog(NULL, "alpha=%x%x%x%x\n", alpha[0],alpha[1],alpha[2],alpha[3]);
285                break;
286            case 0x05:
287            case 0x85:
288                if ((buf_size - pos) < 6)
289                    goto fail;
290                x1 = (buf[pos] << 4) | (buf[pos + 1] >> 4);
291                x2 = ((buf[pos + 1] & 0x0f) << 8) | buf[pos + 2];
292                y1 = (buf[pos + 3] << 4) | (buf[pos + 4] >> 4);
293                y2 = ((buf[pos + 4] & 0x0f) << 8) | buf[pos + 5];
294                if (cmd & 0x80)
295                    is_8bit = 1;
296                av_dlog(NULL, "x1=%d x2=%d y1=%d y2=%d\n", x1, x2, y1, y2);
297                pos += 6;
298                break;
299            case 0x06:
300                if ((buf_size - pos) < 4)
301                    goto fail;
302                offset1 = AV_RB16(buf + pos);
303                offset2 = AV_RB16(buf + pos + 2);
304                av_dlog(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
305                pos += 4;
306                break;
307            case 0x86:
308                if ((buf_size - pos) < 8)
309                    goto fail;
310                offset1 = AV_RB32(buf + pos);
311                offset2 = AV_RB32(buf + pos + 4);
312                av_dlog(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
313                pos += 8;
314                break;
315
316            case 0x83:
317                /* HD set palette */
318                if ((buf_size - pos) < 768)
319                    goto fail;
320                yuv_palette = buf + pos;
321                pos += 768;
322                break;
323            case 0x84:
324                /* HD set contrast (alpha) */
325                if ((buf_size - pos) < 256)
326                    goto fail;
327                for (i = 0; i < 256; i++)
328                    alpha[i] = 0xFF - buf[pos+i];
329                pos += 256;
330                break;
331
332            case 0xff:
333                goto the_end;
334            default:
335                av_dlog(NULL, "unrecognised subpicture command 0x%x\n", cmd);
336                goto the_end;
337            }
338        }
339    the_end:
340        if (offset1 >= 0) {
341            int w, h;
342            uint8_t *bitmap;
343
344            /* decode the bitmap */
345            w = x2 - x1 + 1;
346            if (w < 0)
347                w = 0;
348            h = y2 - y1 + 1;
349            if (h < 0)
350                h = 0;
351            if (w > 0 && h > 0) {
352                reset_rects(sub_header);
353
354                bitmap = av_malloc(w * h);
355                sub_header->rects = av_mallocz(sizeof(*sub_header->rects));
356                sub_header->rects[0] = av_mallocz(sizeof(AVSubtitleRect));
357                sub_header->num_rects = 1;
358                sub_header->rects[0]->pict.data[0] = bitmap;
359                decode_rle(bitmap, w * 2, w, (h + 1) / 2,
360                           buf, offset1, buf_size, is_8bit);
361                decode_rle(bitmap + w, w * 2, w, h / 2,
362                           buf, offset2, buf_size, is_8bit);
363                sub_header->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
364                if (is_8bit) {
365                    if (yuv_palette == 0)
366                        goto fail;
367                    sub_header->rects[0]->nb_colors = 256;
368                    yuv_a_to_rgba(yuv_palette, alpha, (uint32_t*)sub_header->rects[0]->pict.data[1], 256);
369                } else {
370                    sub_header->rects[0]->nb_colors = 4;
371                    guess_palette(ctx, (uint32_t*)sub_header->rects[0]->pict.data[1],
372                                  0xffff00);
373                }
374                sub_header->rects[0]->x = x1;
375                sub_header->rects[0]->y = y1;
376                sub_header->rects[0]->w = w;
377                sub_header->rects[0]->h = h;
378                sub_header->rects[0]->type = SUBTITLE_BITMAP;
379                sub_header->rects[0]->pict.linesize[0] = w;
380                sub_header->rects[0]->flags = is_menu ? AV_SUBTITLE_FLAG_FORCED : 0;
381            }
382        }
383        if (next_cmd_pos < cmd_pos) {
384            av_log(NULL, AV_LOG_ERROR, "Invalid command offset\n");
385            break;
386        }
387        if (next_cmd_pos == cmd_pos)
388            break;
389        cmd_pos = next_cmd_pos;
390    }
391    if (sub_header->num_rects > 0)
392        return is_menu;
393 fail:
394    reset_rects(sub_header);
395    return -1;
396}
397
398static int is_transp(const uint8_t *buf, int pitch, int n,
399                     const uint8_t *transp_color)
400{
401    int i;
402    for(i = 0; i < n; i++) {
403        if (!transp_color[*buf])
404            return 0;
405        buf += pitch;
406    }
407    return 1;
408}
409
410/* return 0 if empty rectangle, 1 if non empty */
411static int find_smallest_bounding_rectangle(AVSubtitle *s)
412{
413    uint8_t transp_color[256] = { 0 };
414    int y1, y2, x1, x2, y, w, h, i;
415    uint8_t *bitmap;
416
417    if (s->num_rects == 0 || s->rects == NULL || s->rects[0]->w <= 0 || s->rects[0]->h <= 0)
418        return 0;
419
420    for(i = 0; i < s->rects[0]->nb_colors; i++) {
421        if ((((uint32_t*)s->rects[0]->pict.data[1])[i] >> 24) == 0)
422            transp_color[i] = 1;
423    }
424    y1 = 0;
425    while (y1 < s->rects[0]->h && is_transp(s->rects[0]->pict.data[0] + y1 * s->rects[0]->pict.linesize[0],
426                                  1, s->rects[0]->w, transp_color))
427        y1++;
428    if (y1 == s->rects[0]->h) {
429        av_freep(&s->rects[0]->pict.data[0]);
430        s->rects[0]->w = s->rects[0]->h = 0;
431        return 0;
432    }
433
434    y2 = s->rects[0]->h - 1;
435    while (y2 > 0 && is_transp(s->rects[0]->pict.data[0] + y2 * s->rects[0]->pict.linesize[0], 1,
436                               s->rects[0]->w, transp_color))
437        y2--;
438    x1 = 0;
439    while (x1 < (s->rects[0]->w - 1) && is_transp(s->rects[0]->pict.data[0] + x1, s->rects[0]->pict.linesize[0],
440                                        s->rects[0]->h, transp_color))
441        x1++;
442    x2 = s->rects[0]->w - 1;
443    while (x2 > 0 && is_transp(s->rects[0]->pict.data[0] + x2, s->rects[0]->pict.linesize[0], s->rects[0]->h,
444                                  transp_color))
445        x2--;
446    w = x2 - x1 + 1;
447    h = y2 - y1 + 1;
448    bitmap = av_malloc(w * h);
449    if (!bitmap)
450        return 1;
451    for(y = 0; y < h; y++) {
452        memcpy(bitmap + w * y, s->rects[0]->pict.data[0] + x1 + (y1 + y) * s->rects[0]->pict.linesize[0], w);
453    }
454    av_freep(&s->rects[0]->pict.data[0]);
455    s->rects[0]->pict.data[0] = bitmap;
456    s->rects[0]->pict.linesize[0] = w;
457    s->rects[0]->w = w;
458    s->rects[0]->h = h;
459    s->rects[0]->x += x1;
460    s->rects[0]->y += y1;
461    return 1;
462}
463
464#ifdef DEBUG
465#define ALPHA_MIX(A,BACK,FORE) (((255-(A)) * (BACK) + (A) * (FORE)) / 255)
466static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,
467                     uint32_t *rgba_palette)
468{
469    int x, y, alpha;
470    uint32_t v;
471    int back[3] = {0, 255, 0};  /* green background */
472    FILE *f;
473
474    f = fopen(filename, "w");
475    if (!f) {
476        perror(filename);
477        return;
478    }
479    fprintf(f, "P6\n"
480            "%d %d\n"
481            "%d\n",
482            w, h, 255);
483    for(y = 0; y < h; y++) {
484        for(x = 0; x < w; x++) {
485            v = rgba_palette[bitmap[y * w + x]];
486            alpha = v >> 24;
487            putc(ALPHA_MIX(alpha, back[0], (v >> 16) & 0xff), f);
488            putc(ALPHA_MIX(alpha, back[1], (v >> 8) & 0xff), f);
489            putc(ALPHA_MIX(alpha, back[2], (v >> 0) & 0xff), f);
490        }
491    }
492    fclose(f);
493}
494#endif
495
496static int append_to_cached_buf(AVCodecContext *avctx,
497                                const uint8_t *buf, int buf_size)
498{
499    DVDSubContext *ctx = avctx->priv_data;
500
501    if (ctx->buf_size > 0xffff - buf_size) {
502        av_log(avctx, AV_LOG_WARNING, "Attempt to reconstruct "
503               "too large SPU packets aborted.\n");
504        av_freep(&ctx->buf);
505        return AVERROR_INVALIDDATA;
506    }
507    ctx->buf = av_realloc(ctx->buf, ctx->buf_size + buf_size);
508    if (!ctx->buf)
509        return AVERROR(ENOMEM);
510    memcpy(ctx->buf + ctx->buf_size, buf, buf_size);
511    ctx->buf_size += buf_size;
512    return 0;
513}
514
515static int dvdsub_decode(AVCodecContext *avctx,
516                         void *data, int *data_size,
517                         AVPacket *avpkt)
518{
519    DVDSubContext *ctx = avctx->priv_data;
520    const uint8_t *buf = avpkt->data;
521    int buf_size = avpkt->size;
522    AVSubtitle *sub = data;
523    int is_menu;
524
525    if (ctx->buf) {
526        int ret = append_to_cached_buf(avctx, buf, buf_size);
527        if (ret < 0) {
528            *data_size = 0;
529            return ret;
530        }
531        buf = ctx->buf;
532        buf_size = ctx->buf_size;
533    }
534
535    is_menu = decode_dvd_subtitles(ctx, sub, buf, buf_size);
536    if (is_menu == AVERROR(EAGAIN)) {
537        *data_size = 0;
538        return append_to_cached_buf(avctx, buf, buf_size);
539    }
540
541    if (is_menu < 0) {
542    no_subtitle:
543        *data_size = 0;
544
545        return buf_size;
546    }
547    if (!is_menu && find_smallest_bounding_rectangle(sub) == 0)
548        goto no_subtitle;
549
550#if defined(DEBUG)
551    {
552    char ppm_name[32];
553
554    snprintf(ppm_name, sizeof(ppm_name), "/tmp/%05d.ppm", ctx->sub_id++);
555    av_dlog(NULL, "start=%d ms end =%d ms\n",
556            sub->start_display_time,
557            sub->end_display_time);
558    ppm_save(ppm_name, sub->rects[0]->pict.data[0],
559             sub->rects[0]->w, sub->rects[0]->h, (uint32_t*) sub->rects[0]->pict.data[1]);
560    }
561#endif
562
563    av_freep(&ctx->buf);
564    ctx->buf_size = 0;
565    *data_size = 1;
566    return buf_size;
567}
568
569static void parse_palette(DVDSubContext *ctx, char *p)
570{
571    int i;
572
573    ctx->has_palette = 1;
574    for(i=0;i<16;i++) {
575        ctx->palette[i] = strtoul(p, &p, 16);
576        while(*p == ',' || av_isspace(*p))
577            p++;
578    }
579}
580
581static int dvdsub_parse_extradata(AVCodecContext *avctx)
582{
583    DVDSubContext *ctx = (DVDSubContext*) avctx->priv_data;
584    char *dataorig, *data;
585
586    if (!avctx->extradata || !avctx->extradata_size)
587        return 1;
588
589    dataorig = data = av_malloc(avctx->extradata_size+1);
590    if (!data)
591        return AVERROR(ENOMEM);
592    memcpy(data, avctx->extradata, avctx->extradata_size);
593    data[avctx->extradata_size] = '\0';
594
595    for(;;) {
596        int pos = strcspn(data, "\n\r");
597        if (pos==0 && *data==0)
598            break;
599
600        if (strncmp("palette:", data, 8) == 0) {
601            parse_palette(ctx, data + 8);
602        } else if (strncmp("size:", data, 5) == 0) {
603            int w, h;
604            if (sscanf(data + 5, "%dx%d", &w, &h) == 2) {
605               int ret = ff_set_dimensions(avctx, w, h);
606               if (ret < 0) {
607                   av_free(dataorig);
608                   return ret;
609               }
610            }
611        }
612
613        data += pos;
614        data += strspn(data, "\n\r");
615    }
616
617    av_free(dataorig);
618    return 1;
619}
620
621static av_cold int dvdsub_init(AVCodecContext *avctx)
622{
623    DVDSubContext *ctx = avctx->priv_data;
624    int ret;
625
626    if ((ret = dvdsub_parse_extradata(avctx)) < 0)
627        return ret;
628
629    if (ctx->palette_str)
630        parse_palette(ctx, ctx->palette_str);
631    if (ctx->has_palette) {
632        int i;
633        av_log(avctx, AV_LOG_DEBUG, "palette:");
634        for(i=0;i<16;i++)
635            av_log(avctx, AV_LOG_DEBUG, " 0x%06x", ctx->palette[i]);
636        av_log(avctx, AV_LOG_DEBUG, "\n");
637    }
638
639    return 1;
640}
641
642static av_cold int dvdsub_close(AVCodecContext *avctx)
643{
644    DVDSubContext *ctx = avctx->priv_data;
645    av_freep(&ctx->buf);
646    ctx->buf_size = 0;
647    return 0;
648}
649
650#define OFFSET(field) offsetof(DVDSubContext, field)
651#define VD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
652static const AVOption options[] = {
653    { "palette", "set the global palette", OFFSET(palette_str), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, VD },
654    { NULL }
655};
656static const AVClass dvdsub_class = {
657    .class_name = "dvdsubdec",
658    .item_name  = av_default_item_name,
659    .option     = options,
660    .version    = LIBAVUTIL_VERSION_INT,
661};
662
663AVCodec ff_dvdsub_decoder = {
664    .name           = "dvdsub",
665    .long_name      = NULL_IF_CONFIG_SMALL("DVD subtitles"),
666    .type           = AVMEDIA_TYPE_SUBTITLE,
667    .id             = AV_CODEC_ID_DVD_SUBTITLE,
668    .priv_data_size = sizeof(DVDSubContext),
669    .init           = dvdsub_init,
670    .decode         = dvdsub_decode,
671    .close          = dvdsub_close,
672    .priv_class     = &dvdsub_class,
673};
674