1/*
2 * Teletext decoding for ffmpeg
3 * Copyright (c) 2005-2010, 2012 Wolfram Gloger
4 * Copyright (c) 2013 Marton Balint
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include "avcodec.h"
22#include "libavcodec/ass.h"
23#include "libavutil/opt.h"
24#include "libavutil/bprint.h"
25#include "libavutil/intreadwrite.h"
26#include "libavutil/log.h"
27
28#include <libzvbi.h>
29
30#define TEXT_MAXSZ    (25 * (56 + 1) * 4 + 2)
31#define VBI_NB_COLORS 40
32#define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
33#define VBI_R(rgba)   (((rgba) >> 0) & 0xFF)
34#define VBI_G(rgba)   (((rgba) >> 8) & 0xFF)
35#define VBI_B(rgba)   (((rgba) >> 16) & 0xFF)
36#define VBI_A(rgba)   (((rgba) >> 24) & 0xFF)
37#define MAX_BUFFERED_PAGES 25
38#define BITMAP_CHAR_WIDTH  12
39#define BITMAP_CHAR_HEIGHT 10
40#define MAX_SLICES 64
41
42typedef struct TeletextPage
43{
44    AVSubtitleRect *sub_rect;
45    int pgno;
46    int subno;
47    int64_t pts;
48} TeletextPage;
49
50typedef struct TeletextContext
51{
52    AVClass        *class;
53    char           *pgno;
54    int             x_offset;
55    int             y_offset;
56    int             format_id; /* 0 = bitmap, 1 = text/ass */
57    int             chop_top;
58    int             sub_duration; /* in msec */
59    int             transparent_bg;
60    int             chop_spaces;
61
62    int             lines_processed;
63    TeletextPage    *pages;
64    int             nb_pages;
65    int64_t         pts;
66    int             handler_ret;
67
68    vbi_decoder *   vbi;
69#ifdef DEBUG
70    vbi_export *    ex;
71#endif
72    vbi_sliced      sliced[MAX_SLICES];
73} TeletextContext;
74
75static int chop_spaces_utf8(const unsigned char* t, int len)
76{
77    t += len;
78    while (len > 0) {
79        if (*--t != ' ' || (len-1 > 0 && *(t-1) & 0x80))
80            break;
81        --len;
82    }
83    return len;
84}
85
86static void subtitle_rect_free(AVSubtitleRect **sub_rect)
87{
88    av_freep(&(*sub_rect)->pict.data[0]);
89    av_freep(&(*sub_rect)->pict.data[1]);
90    av_freep(&(*sub_rect)->ass);
91    av_freep(sub_rect);
92}
93
94static int create_ass_text(TeletextContext *ctx, const char *text, char **ass)
95{
96    int ret;
97    AVBPrint buf, buf2;
98    const int ts_start    = av_rescale_q(ctx->pts,          AV_TIME_BASE_Q,        (AVRational){1, 100});
99    const int ts_duration = av_rescale_q(ctx->sub_duration, (AVRational){1, 1000}, (AVRational){1, 100});
100
101    /* First we escape the plain text into buf. */
102    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
103    ff_ass_bprint_text_event(&buf, text, strlen(text), "", 0);
104
105    if (!av_bprint_is_complete(&buf)) {
106        av_bprint_finalize(&buf, NULL);
107        return AVERROR(ENOMEM);
108    }
109
110    /* Then we create the ass dialog line in buf2 from the escaped text in buf. */
111    av_bprint_init(&buf2, 0, AV_BPRINT_SIZE_UNLIMITED);
112    ff_ass_bprint_dialog(&buf2, buf.str, ts_start, ts_duration, 0);
113    av_bprint_finalize(&buf, NULL);
114
115    if (!av_bprint_is_complete(&buf2)) {
116        av_bprint_finalize(&buf2, NULL);
117        return AVERROR(ENOMEM);
118    }
119
120    if ((ret = av_bprint_finalize(&buf2, ass)) < 0)
121        return ret;
122
123    return 0;
124}
125
126/* Draw a page as text */
127static int gen_sub_text(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page, int chop_top)
128{
129    const char *in;
130    AVBPrint buf;
131    char *vbi_text = av_malloc(TEXT_MAXSZ);
132    int sz;
133
134    if (!vbi_text)
135        return AVERROR(ENOMEM);
136
137    sz = vbi_print_page_region(page, vbi_text, TEXT_MAXSZ-1, "UTF-8",
138                                   /*table mode*/ TRUE, FALSE,
139                                   0,             chop_top,
140                                   page->columns, page->rows-chop_top);
141    if (sz <= 0) {
142        av_log(ctx, AV_LOG_ERROR, "vbi_print error\n");
143        av_free(vbi_text);
144        return AVERROR_EXTERNAL;
145    }
146    vbi_text[sz] = '\0';
147    in  = vbi_text;
148    av_bprint_init(&buf, 0, TEXT_MAXSZ);
149
150    if (ctx->chop_spaces) {
151        for (;;) {
152            int nl, sz;
153
154            // skip leading spaces and newlines
155            in += strspn(in, " \n");
156            // compute end of row
157            for (nl = 0; in[nl]; ++nl)
158                if (in[nl] == '\n' && (nl==0 || !(in[nl-1] & 0x80)))
159                    break;
160            if (!in[nl])
161                break;
162            // skip trailing spaces
163            sz = chop_spaces_utf8(in, nl);
164            av_bprint_append_data(&buf, in, sz);
165            av_bprintf(&buf, "\n");
166            in += nl;
167        }
168    } else {
169        av_bprintf(&buf, "%s\n", vbi_text);
170    }
171    av_free(vbi_text);
172
173    if (!av_bprint_is_complete(&buf)) {
174        av_bprint_finalize(&buf, NULL);
175        return AVERROR(ENOMEM);
176    }
177
178    if (buf.len) {
179        int ret;
180        sub_rect->type = SUBTITLE_ASS;
181        if ((ret = create_ass_text(ctx, buf.str, &sub_rect->ass)) < 0) {
182            av_bprint_finalize(&buf, NULL);
183            return ret;
184        }
185        av_log(ctx, AV_LOG_DEBUG, "subtext:%s:txetbus\n", sub_rect->ass);
186    } else {
187        sub_rect->type = SUBTITLE_NONE;
188    }
189    av_bprint_finalize(&buf, NULL);
190    return 0;
191}
192
193static void fix_transparency(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page,
194                             int chop_top, uint8_t transparent_color, int resx, int resy)
195{
196    int iy;
197
198    // Hack for transparency, inspired by VLC code...
199    for (iy = 0; iy < resy; iy++) {
200        uint8_t *pixel = sub_rect->pict.data[0] + iy * sub_rect->pict.linesize[0];
201        vbi_char *vc = page->text + (iy / BITMAP_CHAR_HEIGHT + chop_top) * page->columns;
202        vbi_char *vcnext = vc + page->columns;
203        for (; vc < vcnext; vc++) {
204            uint8_t *pixelnext = pixel + BITMAP_CHAR_WIDTH;
205            switch (vc->opacity) {
206                case VBI_TRANSPARENT_SPACE:
207                    memset(pixel, transparent_color, BITMAP_CHAR_WIDTH);
208                    break;
209                case VBI_OPAQUE:
210                case VBI_SEMI_TRANSPARENT:
211                    if (!ctx->transparent_bg)
212                        break;
213                case VBI_TRANSPARENT_FULL:
214                    for(; pixel < pixelnext; pixel++)
215                        if (*pixel == vc->background)
216                            *pixel = transparent_color;
217                    break;
218            }
219            pixel = pixelnext;
220        }
221    }
222}
223
224/* Draw a page as bitmap */
225static int gen_sub_bitmap(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page, int chop_top)
226{
227    int resx = page->columns * BITMAP_CHAR_WIDTH;
228    int resy = (page->rows - chop_top) * BITMAP_CHAR_HEIGHT;
229    uint8_t ci, cmax = 0;
230    int ret;
231    vbi_char *vc = page->text + (chop_top * page->columns);
232    vbi_char *vcend = page->text + (page->rows * page->columns);
233
234    for (; vc < vcend; vc++) {
235        if (vc->opacity != VBI_TRANSPARENT_SPACE) {
236            cmax = VBI_NB_COLORS;
237            break;
238        }
239    }
240
241    if (cmax == 0) {
242        av_log(ctx, AV_LOG_DEBUG, "dropping empty page %3x\n", page->pgno);
243        sub_rect->type = SUBTITLE_NONE;
244        return 0;
245    }
246
247    if ((ret = avpicture_alloc(&sub_rect->pict, AV_PIX_FMT_PAL8, resx, resy)) < 0)
248        return ret;
249    // Yes, we want to allocate the palette on our own because AVSubtitle works this way
250    sub_rect->pict.data[1] = NULL;
251
252    vbi_draw_vt_page_region(page, VBI_PIXFMT_PAL8,
253                            sub_rect->pict.data[0], sub_rect->pict.linesize[0],
254                            0, chop_top, page->columns, page->rows - chop_top,
255                            /*reveal*/ 1, /*flash*/ 1);
256
257    fix_transparency(ctx, sub_rect, page, chop_top, cmax, resx, resy);
258    sub_rect->x = ctx->x_offset;
259    sub_rect->y = ctx->y_offset + chop_top * BITMAP_CHAR_HEIGHT;
260    sub_rect->w = resx;
261    sub_rect->h = resy;
262    sub_rect->nb_colors = (int)cmax + 1;
263    sub_rect->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
264    if (!sub_rect->pict.data[1]) {
265        av_freep(&sub_rect->pict.data[0]);
266        return AVERROR(ENOMEM);
267    }
268    for (ci = 0; ci < cmax; ci++) {
269        int r, g, b, a;
270
271        r = VBI_R(page->color_map[ci]);
272        g = VBI_G(page->color_map[ci]);
273        b = VBI_B(page->color_map[ci]);
274        a = VBI_A(page->color_map[ci]);
275        ((uint32_t *)sub_rect->pict.data[1])[ci] = RGBA(r, g, b, a);
276        av_dlog(ctx, "palette %0x\n", ((uint32_t *)sub_rect->pict.data[1])[ci]);
277    }
278    ((uint32_t *)sub_rect->pict.data[1])[cmax] = RGBA(0, 0, 0, 0);
279    sub_rect->type = SUBTITLE_BITMAP;
280    return 0;
281}
282
283static void handler(vbi_event *ev, void *user_data)
284{
285    TeletextContext *ctx = user_data;
286    TeletextPage *new_pages;
287    vbi_page page;
288    int res;
289    char pgno_str[12];
290    vbi_subno subno;
291    vbi_page_type vpt;
292    int chop_top;
293    char *lang;
294
295    snprintf(pgno_str, sizeof pgno_str, "%03x", ev->ev.ttx_page.pgno);
296    av_log(ctx, AV_LOG_DEBUG, "decoded page %s.%02x\n",
297           pgno_str, ev->ev.ttx_page.subno & 0xFF);
298
299    if (strcmp(ctx->pgno, "*") && !strstr(ctx->pgno, pgno_str))
300        return;
301    if (ctx->handler_ret < 0)
302        return;
303
304    res = vbi_fetch_vt_page(ctx->vbi, &page,
305                            ev->ev.ttx_page.pgno,
306                            ev->ev.ttx_page.subno,
307                            VBI_WST_LEVEL_3p5, 25, TRUE);
308
309    if (!res)
310        return;
311
312#ifdef DEBUG
313    fprintf(stderr, "\nSaving res=%d dy0=%d dy1=%d...\n",
314            res, page.dirty.y0, page.dirty.y1);
315    fflush(stderr);
316
317    if (!vbi_export_stdio(ctx->ex, stderr, &page))
318        fprintf(stderr, "failed: %s\n", vbi_export_errstr(ctx->ex));
319#endif
320
321    vpt = vbi_classify_page(ctx->vbi, ev->ev.ttx_page.pgno, &subno, &lang);
322    chop_top = ctx->chop_top ||
323        ((page.rows > 1) && (vpt == VBI_SUBTITLE_PAGE));
324
325    av_log(ctx, AV_LOG_DEBUG, "%d x %d page chop:%d\n",
326           page.columns, page.rows, chop_top);
327
328    if (ctx->nb_pages < MAX_BUFFERED_PAGES) {
329        if ((new_pages = av_realloc_array(ctx->pages, ctx->nb_pages + 1, sizeof(TeletextPage)))) {
330            TeletextPage *cur_page = new_pages + ctx->nb_pages;
331            ctx->pages = new_pages;
332            cur_page->sub_rect = av_mallocz(sizeof(*cur_page->sub_rect));
333            cur_page->pts = ctx->pts;
334            cur_page->pgno = ev->ev.ttx_page.pgno;
335            cur_page->subno = ev->ev.ttx_page.subno;
336            if (cur_page->sub_rect) {
337                res = (ctx->format_id == 0) ?
338                    gen_sub_bitmap(ctx, cur_page->sub_rect, &page, chop_top) :
339                    gen_sub_text  (ctx, cur_page->sub_rect, &page, chop_top);
340                if (res < 0) {
341                    av_freep(&cur_page->sub_rect);
342                    ctx->handler_ret = res;
343                } else {
344                    ctx->pages[ctx->nb_pages++] = *cur_page;
345                }
346            } else {
347                ctx->handler_ret = AVERROR(ENOMEM);
348            }
349        } else {
350            ctx->handler_ret = AVERROR(ENOMEM);
351        }
352    } else {
353        //TODO: If multiple packets contain more than one page, pages may got queued up, and this may happen...
354        av_log(ctx, AV_LOG_ERROR, "Buffered too many pages, dropping page %s.\n", pgno_str);
355        ctx->handler_ret = AVERROR(ENOSYS);
356    }
357
358    vbi_unref_page(&page);
359}
360
361static inline int data_identifier_is_teletext(int data_identifier) {
362    /* See EN 301 775 section 4.4.2. */
363    return (data_identifier >= 0x10 && data_identifier <= 0x1F ||
364            data_identifier >= 0x99 && data_identifier <= 0x9B);
365}
366
367static int slice_to_vbi_lines(TeletextContext *ctx, uint8_t* buf, int size)
368{
369    int lines = 0;
370    while (size >= 2 && lines < MAX_SLICES) {
371        int data_unit_id     = buf[0];
372        int data_unit_length = buf[1];
373        if (data_unit_length + 2 > size)
374            return AVERROR_INVALIDDATA;
375        if (data_unit_id == 0x02 || data_unit_id == 0x03) {
376            if (data_unit_length != 0x2c)
377                return AVERROR_INVALIDDATA;
378            else {
379                int line_offset  = buf[2] & 0x1f;
380                int field_parity = buf[2] & 0x20;
381                int i;
382                ctx->sliced[lines].id = VBI_SLICED_TELETEXT_B;
383                ctx->sliced[lines].line = (line_offset > 0 ? (line_offset + (field_parity ? 0 : 313)) : 0);
384                for (i = 0; i < 42; i++)
385                    ctx->sliced[lines].data[i] = vbi_rev8(buf[4 + i]);
386                lines++;
387            }
388        }
389        size -= data_unit_length + 2;
390        buf += data_unit_length + 2;
391    }
392    if (size)
393        av_log(ctx, AV_LOG_WARNING, "%d bytes remained after slicing data\n", size);
394    return lines;
395}
396
397static int teletext_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *pkt)
398{
399    TeletextContext *ctx = avctx->priv_data;
400    AVSubtitle      *sub = data;
401    int             ret = 0;
402
403    if (!ctx->vbi) {
404        if (!(ctx->vbi = vbi_decoder_new()))
405            return AVERROR(ENOMEM);
406        if (!vbi_event_handler_add(ctx->vbi, VBI_EVENT_TTX_PAGE, handler, ctx)) {
407            vbi_decoder_delete(ctx->vbi);
408            ctx->vbi = NULL;
409            return AVERROR(ENOMEM);
410        }
411    }
412
413    if (avctx->pkt_timebase.den && pkt->pts != AV_NOPTS_VALUE)
414        ctx->pts = av_rescale_q(pkt->pts, avctx->pkt_timebase, AV_TIME_BASE_Q);
415
416    if (pkt->size) {
417        int lines;
418        const int full_pes_size = pkt->size + 45; /* PES header is 45 bytes */
419
420        // We allow unreasonably big packets, even if the standard only allows a max size of 1472
421        if (full_pes_size < 184 || full_pes_size > 65504 || full_pes_size % 184 != 0)
422            return AVERROR_INVALIDDATA;
423
424        ctx->handler_ret = pkt->size;
425
426        if (data_identifier_is_teletext(*pkt->data)) {
427            if ((lines = slice_to_vbi_lines(ctx, pkt->data + 1, pkt->size - 1)) < 0)
428                return lines;
429            av_dlog(avctx, "ctx=%p buf_size=%d lines=%u pkt_pts=%7.3f\n",
430                    ctx, pkt->size, lines, (double)pkt->pts/90000.0);
431            if (lines > 0) {
432#ifdef DEBUG
433                int i;
434                av_log(avctx, AV_LOG_DEBUG, "line numbers:");
435                for(i = 0; i < lines; i++)
436                    av_log(avctx, AV_LOG_DEBUG, " %d", ctx->sliced[i].line);
437                av_log(avctx, AV_LOG_DEBUG, "\n");
438#endif
439                vbi_decode(ctx->vbi, ctx->sliced, lines, 0.0);
440                ctx->lines_processed += lines;
441            }
442        }
443        ctx->pts = AV_NOPTS_VALUE;
444        ret = ctx->handler_ret;
445    }
446
447    if (ret < 0)
448        return ret;
449
450    // is there a subtitle to pass?
451    if (ctx->nb_pages) {
452        int i;
453        sub->format = ctx->format_id;
454        sub->start_display_time = 0;
455        sub->end_display_time = ctx->sub_duration;
456        sub->num_rects = 0;
457        sub->pts = ctx->pages->pts;
458
459        if (ctx->pages->sub_rect->type != SUBTITLE_NONE) {
460            sub->rects = av_malloc(sizeof(*sub->rects));
461            if (sub->rects) {
462                sub->num_rects = 1;
463                sub->rects[0] = ctx->pages->sub_rect;
464            } else {
465                ret = AVERROR(ENOMEM);
466            }
467        } else {
468            av_log(avctx, AV_LOG_DEBUG, "sending empty sub\n");
469            sub->rects = NULL;
470        }
471        if (!sub->rects) // no rect was passed
472            subtitle_rect_free(&ctx->pages->sub_rect);
473
474        for (i = 0; i < ctx->nb_pages - 1; i++)
475            ctx->pages[i] = ctx->pages[i + 1];
476        ctx->nb_pages--;
477
478        if (ret >= 0)
479            *data_size = 1;
480    } else
481        *data_size = 0;
482
483    return ret;
484}
485
486static int teletext_init_decoder(AVCodecContext *avctx)
487{
488    TeletextContext *ctx = avctx->priv_data;
489    unsigned int maj, min, rev;
490
491    vbi_version(&maj, &min, &rev);
492    if (!(maj > 0 || min > 2 || min == 2 && rev >= 26)) {
493        av_log(avctx, AV_LOG_ERROR, "decoder needs zvbi version >= 0.2.26.\n");
494        return AVERROR_EXTERNAL;
495    }
496
497    if (ctx->format_id == 0) {
498        avctx->width  = 41 * BITMAP_CHAR_WIDTH;
499        avctx->height = 25 * BITMAP_CHAR_HEIGHT;
500    }
501
502    ctx->vbi = NULL;
503    ctx->pts = AV_NOPTS_VALUE;
504
505#ifdef DEBUG
506    {
507        char *t;
508        ctx->ex = vbi_export_new("text", &t);
509    }
510#endif
511    av_log(avctx, AV_LOG_VERBOSE, "page filter: %s\n", ctx->pgno);
512    return (ctx->format_id == 1) ? ff_ass_subtitle_header_default(avctx) : 0;
513}
514
515static int teletext_close_decoder(AVCodecContext *avctx)
516{
517    TeletextContext *ctx = avctx->priv_data;
518
519    av_dlog(avctx, "lines_total=%u\n", ctx->lines_processed);
520    while (ctx->nb_pages)
521        subtitle_rect_free(&ctx->pages[--ctx->nb_pages].sub_rect);
522    av_freep(&ctx->pages);
523
524    vbi_decoder_delete(ctx->vbi);
525    ctx->vbi = NULL;
526    ctx->pts = AV_NOPTS_VALUE;
527    return 0;
528}
529
530static void teletext_flush(AVCodecContext *avctx)
531{
532    teletext_close_decoder(avctx);
533}
534
535#define OFFSET(x) offsetof(TeletextContext, x)
536#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
537static const AVOption options[] = {
538    {"txt_page",        "list of teletext page numbers to decode, * is all", OFFSET(pgno),           AV_OPT_TYPE_STRING, {.str = "*"},      0, 0,        SD},
539    {"txt_chop_top",    "discards the top teletext line",                    OFFSET(chop_top),       AV_OPT_TYPE_INT,    {.i64 = 1},        0, 1,        SD},
540    {"txt_format",      "format of the subtitles (bitmap or text)",          OFFSET(format_id),      AV_OPT_TYPE_INT,    {.i64 = 0},        0, 1,        SD,  "txt_format"},
541    {"bitmap",          NULL,                                                0,                      AV_OPT_TYPE_CONST,  {.i64 = 0},        0, 0,        SD,  "txt_format"},
542    {"text",            NULL,                                                0,                      AV_OPT_TYPE_CONST,  {.i64 = 1},        0, 0,        SD,  "txt_format"},
543    {"txt_left",        "x offset of generated bitmaps",                     OFFSET(x_offset),       AV_OPT_TYPE_INT,    {.i64 = 0},        0, 65535,    SD},
544    {"txt_top",         "y offset of generated bitmaps",                     OFFSET(y_offset),       AV_OPT_TYPE_INT,    {.i64 = 0},        0, 65535,    SD},
545    {"txt_chop_spaces", "chops leading and trailing spaces from text",       OFFSET(chop_spaces),    AV_OPT_TYPE_INT,    {.i64 = 1},        0, 1,        SD},
546    {"txt_duration",    "display duration of teletext pages in msecs",       OFFSET(sub_duration),   AV_OPT_TYPE_INT,    {.i64 = 30000},    0, 86400000, SD},
547    {"txt_transparent", "force transparent background of the teletext",      OFFSET(transparent_bg), AV_OPT_TYPE_INT,    {.i64 = 0},        0, 1,        SD},
548    { NULL },
549};
550
551static const AVClass teletext_class = {
552    .class_name = "libzvbi_teletextdec",
553    .item_name  = av_default_item_name,
554    .option     = options,
555    .version    = LIBAVUTIL_VERSION_INT,
556};
557
558AVCodec ff_libzvbi_teletext_decoder = {
559    .name      = "libzvbi_teletextdec",
560    .long_name = NULL_IF_CONFIG_SMALL("Libzvbi DVB teletext decoder"),
561    .type      = AVMEDIA_TYPE_SUBTITLE,
562    .id        = AV_CODEC_ID_DVB_TELETEXT,
563    .priv_data_size = sizeof(TeletextContext),
564    .init      = teletext_init_decoder,
565    .close     = teletext_close_decoder,
566    .decode    = teletext_decode_frame,
567    .capabilities = CODEC_CAP_DELAY,
568    .flush     = teletext_flush,
569    .priv_class= &teletext_class,
570};
571