2 * Closed Caption Decoding
3 * Copyright (c) 2015 Anshul Maheshwari
5 * This file is part of FFmpeg.
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.
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.
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
24 #include "codec_internal.h"
25 #include "libavutil/opt.h"
27 #define SCREEN_ROWS 15
28 #define SCREEN_COLUMNS 32
30 #define SET_FLAG(var, val) ( (var) |= ( 1 << (val)) )
31 #define UNSET_FLAG(var, val) ( (var) &= ~( 1 << (val)) )
32 #define CHECK_FLAG(var, val) ( (var) & ( 1 << (val)) )
34 static const AVRational ms_tb = {1, 1000};
60 CCFONT_UNDERLINED_ITALICS,
65 CCSET_SPECIAL_AMERICAN,
66 CCSET_EXTENDED_SPANISH_FRENCH_MISC,
67 CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH,
70 static const char *charset_overrides[4][128] =
72 [CCSET_BASIC_AMERICAN] = {
85 [CCSET_SPECIAL_AMERICAN] = {
103 [CCSET_EXTENDED_SPANISH_FRENCH_MISC] = {
137 [CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH] = {
173 static const unsigned char bg_attribs[8] = // Color
185 static const unsigned char pac2_attribs[32][3] = // Color, font, ident
187 { CCCOL_WHITE, CCFONT_REGULAR, 0 }, // 0x40 || 0x60
188 { CCCOL_WHITE, CCFONT_UNDERLINED, 0 }, // 0x41 || 0x61
189 { CCCOL_GREEN, CCFONT_REGULAR, 0 }, // 0x42 || 0x62
190 { CCCOL_GREEN, CCFONT_UNDERLINED, 0 }, // 0x43 || 0x63
191 { CCCOL_BLUE, CCFONT_REGULAR, 0 }, // 0x44 || 0x64
192 { CCCOL_BLUE, CCFONT_UNDERLINED, 0 }, // 0x45 || 0x65
193 { CCCOL_CYAN, CCFONT_REGULAR, 0 }, // 0x46 || 0x66
194 { CCCOL_CYAN, CCFONT_UNDERLINED, 0 }, // 0x47 || 0x67
195 { CCCOL_RED, CCFONT_REGULAR, 0 }, // 0x48 || 0x68
196 { CCCOL_RED, CCFONT_UNDERLINED, 0 }, // 0x49 || 0x69
197 { CCCOL_YELLOW, CCFONT_REGULAR, 0 }, // 0x4a || 0x6a
198 { CCCOL_YELLOW, CCFONT_UNDERLINED, 0 }, // 0x4b || 0x6b
199 { CCCOL_MAGENTA, CCFONT_REGULAR, 0 }, // 0x4c || 0x6c
200 { CCCOL_MAGENTA, CCFONT_UNDERLINED, 0 }, // 0x4d || 0x6d
201 { CCCOL_WHITE, CCFONT_ITALICS, 0 }, // 0x4e || 0x6e
202 { CCCOL_WHITE, CCFONT_UNDERLINED_ITALICS, 0 }, // 0x4f || 0x6f
203 { CCCOL_WHITE, CCFONT_REGULAR, 0 }, // 0x50 || 0x70
204 { CCCOL_WHITE, CCFONT_UNDERLINED, 0 }, // 0x51 || 0x71
205 { CCCOL_WHITE, CCFONT_REGULAR, 4 }, // 0x52 || 0x72
206 { CCCOL_WHITE, CCFONT_UNDERLINED, 4 }, // 0x53 || 0x73
207 { CCCOL_WHITE, CCFONT_REGULAR, 8 }, // 0x54 || 0x74
208 { CCCOL_WHITE, CCFONT_UNDERLINED, 8 }, // 0x55 || 0x75
209 { CCCOL_WHITE, CCFONT_REGULAR, 12 }, // 0x56 || 0x76
210 { CCCOL_WHITE, CCFONT_UNDERLINED, 12 }, // 0x57 || 0x77
211 { CCCOL_WHITE, CCFONT_REGULAR, 16 }, // 0x58 || 0x78
212 { CCCOL_WHITE, CCFONT_UNDERLINED, 16 }, // 0x59 || 0x79
213 { CCCOL_WHITE, CCFONT_REGULAR, 20 }, // 0x5a || 0x7a
214 { CCCOL_WHITE, CCFONT_UNDERLINED, 20 }, // 0x5b || 0x7b
215 { CCCOL_WHITE, CCFONT_REGULAR, 24 }, // 0x5c || 0x7c
216 { CCCOL_WHITE, CCFONT_UNDERLINED, 24 }, // 0x5d || 0x7d
217 { CCCOL_WHITE, CCFONT_REGULAR, 28 }, // 0x5e || 0x7e
218 { CCCOL_WHITE, CCFONT_UNDERLINED, 28 } // 0x5f || 0x7f
219 /* total 32 entries */
223 /* +1 is used to compensate null character of string */
224 uint8_t characters[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
225 uint8_t charsets[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
226 uint8_t colors[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
227 uint8_t bgs[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
228 uint8_t fonts[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
230 * Bitmask of used rows; if a bit is not set, the
231 * corresponding row is not used.
232 * for setting row 1 use row | (1 << 0)
233 * for setting row 15 use row | (1 << 14)
238 typedef struct CCaptionSubContext {
241 int real_time_latency_msec;
243 struct Screen screen[2];
246 uint8_t cursor_column;
247 uint8_t cursor_color;
250 uint8_t cursor_charset;
256 int64_t buffer_time[2];
258 int64_t last_real_time;
261 } CCaptionSubContext;
263 static av_cold int init_decoder(AVCodecContext *avctx)
265 CCaptionSubContext *ctx = avctx->priv_data;
267 av_bprint_init(&ctx->buffer[0], 0, AV_BPRINT_SIZE_UNLIMITED);
268 av_bprint_init(&ctx->buffer[1], 0, AV_BPRINT_SIZE_UNLIMITED);
269 /* taking by default roll up to 2 */
270 ctx->mode = CCMODE_ROLLUP;
271 ctx->bg_color = CCCOL_BLACK;
273 ctx->cursor_row = 10;
274 return ff_ass_subtitle_header(avctx, "Monospace",
275 ASS_DEFAULT_FONT_SIZE,
277 ASS_DEFAULT_BACK_COLOR,
280 ASS_DEFAULT_UNDERLINE,
282 ASS_DEFAULT_ALIGNMENT);
285 static av_cold int close_decoder(AVCodecContext *avctx)
287 CCaptionSubContext *ctx = avctx->priv_data;
288 av_bprint_finalize(&ctx->buffer[0], NULL);
289 av_bprint_finalize(&ctx->buffer[1], NULL);
293 static void flush_decoder(AVCodecContext *avctx)
295 CCaptionSubContext *ctx = avctx->priv_data;
296 ctx->screen[0].row_used = 0;
297 ctx->screen[1].row_used = 0;
298 ctx->prev_cmd[0] = 0;
299 ctx->prev_cmd[1] = 0;
300 ctx->mode = CCMODE_ROLLUP;
302 ctx->cursor_row = 10;
303 ctx->cursor_column = 0;
304 ctx->cursor_font = 0;
305 ctx->cursor_color = 0;
306 ctx->bg_color = CCCOL_BLACK;
307 ctx->cursor_charset = 0;
308 ctx->active_screen = 0;
309 ctx->last_real_time = 0;
310 ctx->screen_touched = 0;
311 ctx->buffer_changed = 0;
312 if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
314 av_bprint_clear(&ctx->buffer[0]);
315 av_bprint_clear(&ctx->buffer[1]);
319 * @param ctx closed caption context just to print log
321 static void write_char(CCaptionSubContext *ctx, struct Screen *screen, char ch)
323 uint8_t col = ctx->cursor_column;
324 char *row = screen->characters[ctx->cursor_row];
325 char *font = screen->fonts[ctx->cursor_row];
326 char *color = screen->colors[ctx->cursor_row];
327 char *bg = screen->bgs[ctx->cursor_row];
328 char *charset = screen->charsets[ctx->cursor_row];
330 if (col < SCREEN_COLUMNS) {
332 font[col] = ctx->cursor_font;
333 color[col] = ctx->cursor_color;
334 bg[col] = ctx->bg_color;
335 charset[col] = ctx->cursor_charset;
336 ctx->cursor_charset = CCSET_BASIC_AMERICAN;
337 if (ch) ctx->cursor_column++;
340 /* We have extra space at end only for null character */
341 else if (col == SCREEN_COLUMNS && ch == 0) {
346 av_log(ctx, AV_LOG_WARNING, "Data Ignored since exceeding screen width\n");
352 * This function after validating parity bit, also remove it from data pair.
353 * The first byte doesn't pass parity, we replace it with a solid blank
354 * and process the pair.
355 * If the second byte doesn't pass parity, it returns INVALIDDATA
356 * user can ignore the whole pair and pass the other pair.
358 static int validate_cc_data_pair(const uint8_t *cc_data_pair, uint8_t *hi)
360 uint8_t cc_valid = (*cc_data_pair & 4) >>2;
361 uint8_t cc_type = *cc_data_pair & 3;
363 *hi = cc_data_pair[1];
366 return AVERROR_INVALIDDATA;
368 // if EIA-608 data then verify parity.
369 if (cc_type==0 || cc_type==1) {
370 if (!av_parity(cc_data_pair[2])) {
371 return AVERROR_INVALIDDATA;
373 if (!av_parity(cc_data_pair[1])) {
379 if ((cc_data_pair[0] == 0xFA || cc_data_pair[0] == 0xFC || cc_data_pair[0] == 0xFD)
380 && (cc_data_pair[1] & 0x7F) == 0 && (cc_data_pair[2] & 0x7F) == 0)
381 return AVERROR_PATCHWELCOME;
384 if (cc_type == 3 || cc_type == 2)
385 return AVERROR_PATCHWELCOME;
390 static struct Screen *get_writing_screen(CCaptionSubContext *ctx)
394 // use Inactive screen
395 return ctx->screen + !ctx->active_screen;
400 return ctx->screen + ctx->active_screen;
402 /* It was never an option */
406 static void roll_up(CCaptionSubContext *ctx)
408 struct Screen *screen;
411 if (ctx->mode == CCMODE_TEXT)
414 screen = get_writing_screen(ctx);
416 /* +1 signify cursor_row starts from 0
417 * Can't keep lines less then row cursor pos
419 keep_lines = FFMIN(ctx->cursor_row + 1, ctx->rollup);
421 for (i = 0; i < SCREEN_ROWS; i++) {
422 if (i > ctx->cursor_row - keep_lines && i <= ctx->cursor_row)
424 UNSET_FLAG(screen->row_used, i);
427 for (i = 0; i < keep_lines && screen->row_used; i++) {
428 const int i_row = ctx->cursor_row - keep_lines + i + 1;
430 memcpy(screen->characters[i_row], screen->characters[i_row+1], SCREEN_COLUMNS);
431 memcpy(screen->colors[i_row], screen->colors[i_row+1], SCREEN_COLUMNS);
432 memcpy(screen->bgs[i_row], screen->bgs[i_row+1], SCREEN_COLUMNS);
433 memcpy(screen->fonts[i_row], screen->fonts[i_row+1], SCREEN_COLUMNS);
434 memcpy(screen->charsets[i_row], screen->charsets[i_row+1], SCREEN_COLUMNS);
435 if (CHECK_FLAG(screen->row_used, i_row + 1))
436 SET_FLAG(screen->row_used, i_row);
439 UNSET_FLAG(screen->row_used, ctx->cursor_row);
442 static int capture_screen(CCaptionSubContext *ctx)
445 struct Screen *screen = ctx->screen + ctx->active_screen;
446 enum cc_font prev_font = CCFONT_REGULAR;
447 enum cc_color_code prev_color = CCCOL_WHITE;
448 enum cc_color_code prev_bg_color = CCCOL_BLACK;
449 const int bidx = ctx->buffer_index;
451 av_bprint_clear(&ctx->buffer[bidx]);
453 for (i = 0; screen->row_used && i < SCREEN_ROWS; i++)
455 if (CHECK_FLAG(screen->row_used, i)) {
456 const char *row = screen->characters[i];
457 const char *charset = screen->charsets[i];
459 while (row[j] == ' ' && charset[j] == CCSET_BASIC_AMERICAN)
466 for (i = 0; screen->row_used && i < SCREEN_ROWS; i++)
468 if (CHECK_FLAG(screen->row_used, i)) {
469 const char *row = screen->characters[i];
470 const char *font = screen->fonts[i];
471 const char *bg = screen->bgs[i];
472 const char *color = screen->colors[i];
473 const char *charset = screen->charsets[i];
474 const char *override;
475 int x, y, seen_char = 0;
478 /* skip leading space */
479 while (row[j] == ' ' && charset[j] == CCSET_BASIC_AMERICAN && j < tab)
482 x = ASS_DEFAULT_PLAYRESX * (0.1 + 0.0250 * j);
483 y = ASS_DEFAULT_PLAYRESY * (0.1 + 0.0533 * i);
484 av_bprintf(&ctx->buffer[bidx], "{\\an7}{\\pos(%d,%d)}", x, y);
486 for (; j < SCREEN_COLUMNS; j++) {
487 const char *e_tag = "", *s_tag = "", *c_tag = "", *b_tag = "";
492 if (prev_font != font[j]) {
497 case CCFONT_UNDERLINED:
500 case CCFONT_UNDERLINED_ITALICS:
501 e_tag = "{\\u0}{\\i0}";
508 case CCFONT_UNDERLINED:
511 case CCFONT_UNDERLINED_ITALICS:
512 s_tag = "{\\u1}{\\i1}";
516 if (prev_color != color[j]) {
519 c_tag = "{\\c&HFFFFFF&}";
522 c_tag = "{\\c&H00FF00&}";
525 c_tag = "{\\c&HFF0000&}";
528 c_tag = "{\\c&HFFFF00&}";
531 c_tag = "{\\c&H0000FF&}";
534 c_tag = "{\\c&H00FFFF&}";
537 c_tag = "{\\c&HFF00FF&}";
541 if (prev_bg_color != bg[j]) {
544 b_tag = "{\\3c&HFFFFFF&}";
547 b_tag = "{\\3c&H00FF00&}";
550 b_tag = "{\\3c&HFF0000&}";
553 b_tag = "{\\3c&HFFFF00&}";
556 b_tag = "{\\3c&H0000FF&}";
559 b_tag = "{\\3c&H00FFFF&}";
562 b_tag = "{\\3c&HFF00FF&}";
565 b_tag = "{\\3c&H000000&}";
571 prev_color = color[j];
572 prev_bg_color = bg[j];
573 override = charset_overrides[(int)charset[j]][(int)row[j]];
575 av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%s", e_tag, s_tag, c_tag, b_tag, override);
577 } else if (row[j] == ' ' && !seen_char) {
578 av_bprintf(&ctx->buffer[bidx], "%s%s%s%s\\h", e_tag, s_tag, c_tag, b_tag);
580 av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%c", e_tag, s_tag, c_tag, b_tag, row[j]);
585 av_bprintf(&ctx->buffer[bidx], "\\N");
588 if (!av_bprint_is_complete(&ctx->buffer[bidx]))
589 return AVERROR(ENOMEM);
590 if (screen->row_used && ctx->buffer[bidx].len >= 2) {
591 ctx->buffer[bidx].len -= 2;
592 ctx->buffer[bidx].str[ctx->buffer[bidx].len] = 0;
594 ctx->buffer_changed = 1;
598 static void update_time(CCaptionSubContext *ctx, int64_t pts)
600 ctx->buffer_time[0] = ctx->buffer_time[1];
601 ctx->buffer_time[1] = pts;
604 static void handle_bgattr(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
606 const int i = (lo & 0xf) >> 1;
608 ctx->bg_color = bg_attribs[i];
611 static void handle_textattr(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
614 struct Screen *screen = get_writing_screen(ctx);
619 ctx->cursor_color = pac2_attribs[i][0];
620 ctx->cursor_font = pac2_attribs[i][1];
622 SET_FLAG(screen->row_used, ctx->cursor_row);
623 write_char(ctx, screen, ' ');
626 static void handle_pac(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
628 static const int8_t row_map[] = {
629 11, -1, 1, 2, 3, 4, 12, 13, 14, 15, 5, 6, 7, 8, 9, 10
631 const int index = ( (hi<<1) & 0x0e) | ( (lo>>5) & 0x01 );
632 struct Screen *screen = get_writing_screen(ctx);
635 if (row_map[index] <= 0) {
636 av_log(ctx, AV_LOG_DEBUG, "Invalid pac index encountered\n");
642 ctx->cursor_row = row_map[index] - 1;
643 ctx->cursor_color = pac2_attribs[lo][0];
644 ctx->cursor_font = pac2_attribs[lo][1];
645 ctx->cursor_charset = CCSET_BASIC_AMERICAN;
646 ctx->cursor_column = 0;
647 indent = pac2_attribs[lo][2];
648 for (i = 0; i < indent; i++) {
649 write_char(ctx, screen, ' ');
653 static int handle_edm(CCaptionSubContext *ctx)
655 struct Screen *screen = ctx->screen + ctx->active_screen;
658 // In buffered mode, keep writing to screen until it is wiped.
659 // Before wiping the display, capture contents to emit subtitle.
661 ret = capture_screen(ctx);
663 screen->row_used = 0;
664 ctx->bg_color = CCCOL_BLACK;
666 // In realtime mode, emit an empty caption so the last one doesn't
667 // stay on the screen.
669 ret = capture_screen(ctx);
674 static int handle_eoc(CCaptionSubContext *ctx)
678 ctx->active_screen = !ctx->active_screen;
680 // In buffered mode, we wait til the *next* EOC and
681 // capture what was already on the screen since the last EOC.
683 ret = handle_edm(ctx);
685 ctx->cursor_column = 0;
687 // In realtime mode, we display the buffered contents (after
688 // flipping the buffer to active above) as soon as EOC arrives.
690 ret = capture_screen(ctx);
695 static void handle_delete_end_of_row(CCaptionSubContext *ctx)
697 struct Screen *screen = get_writing_screen(ctx);
698 write_char(ctx, screen, 0);
701 static void handle_char(CCaptionSubContext *ctx, char hi, char lo)
703 struct Screen *screen = get_writing_screen(ctx);
705 SET_FLAG(screen->row_used, ctx->cursor_row);
709 ctx->cursor_charset = CCSET_SPECIAL_AMERICAN;
712 if (ctx->cursor_column > 0)
713 ctx->cursor_column -= 1;
714 ctx->cursor_charset = CCSET_EXTENDED_SPANISH_FRENCH_MISC;
717 if (ctx->cursor_column > 0)
718 ctx->cursor_column -= 1;
719 ctx->cursor_charset = CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH;
722 ctx->cursor_charset = CCSET_BASIC_AMERICAN;
723 write_char(ctx, screen, hi);
728 write_char(ctx, screen, lo);
730 write_char(ctx, screen, 0);
732 if (ctx->mode != CCMODE_POPON)
733 ctx->screen_touched = 1;
736 ff_dlog(ctx, "(%c,%c)\n", hi, lo);
738 ff_dlog(ctx, "(%c)\n", hi);
741 static int process_cc608(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
745 if (hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) {
749 /* set prev command */
750 ctx->prev_cmd[0] = hi;
751 ctx->prev_cmd[1] = lo;
753 if ( (hi == 0x10 && (lo >= 0x40 && lo <= 0x5f)) ||
754 ( (hi >= 0x11 && hi <= 0x17) && (lo >= 0x40 && lo <= 0x7f) ) ) {
755 handle_pac(ctx, hi, lo);
756 } else if ( ( hi == 0x11 && lo >= 0x20 && lo <= 0x2f ) ||
757 ( hi == 0x17 && lo >= 0x2e && lo <= 0x2f) ) {
758 handle_textattr(ctx, hi, lo);
759 } else if ((hi == 0x10 && lo >= 0x20 && lo <= 0x2f)) {
760 handle_bgattr(ctx, hi, lo);
761 } else if (hi == 0x14 || hi == 0x15 || hi == 0x1c) {
764 /* resume caption loading */
765 ctx->mode = CCMODE_POPON;
768 handle_delete_end_of_row(ctx);
773 ctx->rollup = lo - 0x23;
774 ctx->mode = CCMODE_ROLLUP;
777 /* resume direct captioning */
778 ctx->mode = CCMODE_PAINTON;
781 /* resume text display */
782 ctx->mode = CCMODE_TEXT;
785 /* erase display memory */
789 /* carriage return */
790 ff_dlog(ctx, "carriage return\n");
792 ret = capture_screen(ctx);
794 ctx->cursor_column = 0;
797 /* erase buffered (non displayed) memory */
798 // Only in realtime mode. In buffered mode, we re-use the inactive screen
799 // for our own buffering.
800 if (ctx->real_time) {
801 struct Screen *screen = ctx->screen + !ctx->active_screen;
802 screen->row_used = 0;
807 ff_dlog(ctx, "handle_eoc\n");
808 ret = handle_eoc(ctx);
811 ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
814 } else if (hi >= 0x11 && hi <= 0x13) {
815 /* Special characters */
816 handle_char(ctx, hi, lo);
817 } else if (hi >= 0x20) {
818 /* Standard characters (always in pairs) */
819 handle_char(ctx, hi, lo);
820 ctx->prev_cmd[0] = ctx->prev_cmd[1] = 0;
821 } else if (hi == 0x17 && lo >= 0x21 && lo <= 0x23) {
823 /* Tab offsets (spacing) */
824 for (i = 0; i < lo - 0x20; i++) {
825 handle_char(ctx, ' ', 0);
828 /* Ignoring all other non data code */
829 ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
835 static int decode(AVCodecContext *avctx, AVSubtitle *sub,
836 int *got_sub, const AVPacket *avpkt)
838 CCaptionSubContext *ctx = avctx->priv_data;
839 int64_t in_time = sub->pts;
842 int bidx = ctx->buffer_index;
843 const uint8_t *bptr = avpkt->data;
844 int len = avpkt->size;
847 unsigned nb_rect_allocated = 0;
849 for (i = 0; i < len; i += 3) {
850 uint8_t hi, cc_type = bptr[i] & 1;
852 if (ctx->data_field < 0)
853 ctx->data_field = cc_type;
855 if (validate_cc_data_pair(bptr + i, &hi))
858 if (cc_type != ctx->data_field)
861 ret = process_cc608(ctx, hi & 0x7f, bptr[i + 2] & 0x7f);
865 if (!ctx->buffer_changed)
867 ctx->buffer_changed = 0;
869 if (!ctx->real_time && ctx->mode == CCMODE_POPON)
870 ctx->buffer_index = bidx = !ctx->buffer_index;
872 update_time(ctx, in_time);
874 if (ctx->buffer[bidx].str[0] || ctx->real_time) {
875 ff_dlog(ctx, "cdp writing data (%s)\n", ctx->buffer[bidx].str);
876 start_time = ctx->buffer_time[0];
877 sub->pts = start_time;
878 end_time = ctx->buffer_time[1];
880 sub->end_display_time = av_rescale_q(end_time - start_time,
881 AV_TIME_BASE_Q, ms_tb);
883 sub->end_display_time = -1;
884 ret = ff_ass_add_rect2(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL, &nb_rect_allocated);
887 ctx->last_real_time = sub->pts;
888 ctx->screen_touched = 0;
892 if (!bptr && !ctx->real_time && ctx->buffer[!ctx->buffer_index].str[0]) {
893 bidx = !ctx->buffer_index;
894 ret = ff_ass_add_rect2(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL, &nb_rect_allocated);
897 av_bprint_clear(&ctx->buffer[bidx]);
898 sub->pts = ctx->buffer_time[1];
899 sub->end_display_time = av_rescale_q(ctx->buffer_time[1] - ctx->buffer_time[0],
900 AV_TIME_BASE_Q, ms_tb);
901 if (sub->end_display_time == 0)
902 sub->end_display_time = ctx->buffer[bidx].len * 20;
905 if (ctx->real_time && ctx->screen_touched &&
906 sub->pts >= ctx->last_real_time + av_rescale_q(ctx->real_time_latency_msec, ms_tb, AV_TIME_BASE_Q)) {
907 ctx->last_real_time = sub->pts;
908 ctx->screen_touched = 0;
911 ctx->buffer_changed = 0;
913 ret = ff_ass_add_rect2(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL, &nb_rect_allocated);
916 sub->end_display_time = -1;
919 *got_sub = sub->num_rects > 0;
923 #define OFFSET(x) offsetof(CCaptionSubContext, x)
924 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
925 static const AVOption options[] = {
926 { "real_time", "emit subtitle events as they are decoded for real-time display", OFFSET(real_time), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, SD },
927 { "real_time_latency_msec", "minimum elapsed time between emitting real-time subtitle events", OFFSET(real_time_latency_msec), AV_OPT_TYPE_INT, { .i64 = 200 }, 0, 500, SD },
928 { "data_field", "select data field", OFFSET(data_field), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, SD, "data_field" },
929 { "auto", "pick first one that appears", 0, AV_OPT_TYPE_CONST, { .i64 =-1 }, 0, 0, SD, "data_field" },
930 { "first", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, SD, "data_field" },
931 { "second", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, SD, "data_field" },
935 static const AVClass ccaption_dec_class = {
936 .class_name = "Closed caption Decoder",
937 .item_name = av_default_item_name,
939 .version = LIBAVUTIL_VERSION_INT,
942 const FFCodec ff_ccaption_decoder = {
944 CODEC_LONG_NAME("Closed Caption (EIA-608 / CEA-708)"),
945 .p.type = AVMEDIA_TYPE_SUBTITLE,
946 .p.id = AV_CODEC_ID_EIA_608,
947 .p.priv_class = &ccaption_dec_class,
948 .p.capabilities = AV_CODEC_CAP_DELAY,
949 .priv_data_size = sizeof(CCaptionSubContext),
950 .init = init_decoder,
951 .close = close_decoder,
952 .flush = flush_decoder,
953 FF_CODEC_DECODE_SUB_CB(decode),