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.
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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 "libavutil/opt.h"
26 #define SCREEN_ROWS 15
27 #define SCREEN_COLUMNS 32
29 #define SET_FLAG(var, val) ( (var) |= ( 1 << (val)) )
30 #define UNSET_FLAG(var, val) ( (var) &= ~( 1 << (val)) )
31 #define CHECK_FLAG(var, val) ( (var) & ( 1 << (val)) )
35 * 1) handle font and color completely
63 CCFONT_UNDERLINED_ITALICS,
66 static const unsigned char pac2_attribs[32][3] = // Color, font, ident
68 { CCCOL_WHITE, CCFONT_REGULAR, 0 }, // 0x40 || 0x60
69 { CCCOL_WHITE, CCFONT_UNDERLINED, 0 }, // 0x41 || 0x61
70 { CCCOL_GREEN, CCFONT_REGULAR, 0 }, // 0x42 || 0x62
71 { CCCOL_GREEN, CCFONT_UNDERLINED, 0 }, // 0x43 || 0x63
72 { CCCOL_BLUE, CCFONT_REGULAR, 0 }, // 0x44 || 0x64
73 { CCCOL_BLUE, CCFONT_UNDERLINED, 0 }, // 0x45 || 0x65
74 { CCCOL_CYAN, CCFONT_REGULAR, 0 }, // 0x46 || 0x66
75 { CCCOL_CYAN, CCFONT_UNDERLINED, 0 }, // 0x47 || 0x67
76 { CCCOL_RED, CCFONT_REGULAR, 0 }, // 0x48 || 0x68
77 { CCCOL_RED, CCFONT_UNDERLINED, 0 }, // 0x49 || 0x69
78 { CCCOL_YELLOW, CCFONT_REGULAR, 0 }, // 0x4a || 0x6a
79 { CCCOL_YELLOW, CCFONT_UNDERLINED, 0 }, // 0x4b || 0x6b
80 { CCCOL_MAGENTA, CCFONT_REGULAR, 0 }, // 0x4c || 0x6c
81 { CCCOL_MAGENTA, CCFONT_UNDERLINED, 0 }, // 0x4d || 0x6d
82 { CCCOL_WHITE, CCFONT_ITALICS, 0 }, // 0x4e || 0x6e
83 { CCCOL_WHITE, CCFONT_UNDERLINED_ITALICS, 0 }, // 0x4f || 0x6f
84 { CCCOL_WHITE, CCFONT_REGULAR, 0 }, // 0x50 || 0x70
85 { CCCOL_WHITE, CCFONT_UNDERLINED, 0 }, // 0x51 || 0x71
86 { CCCOL_WHITE, CCFONT_REGULAR, 4 }, // 0x52 || 0x72
87 { CCCOL_WHITE, CCFONT_UNDERLINED, 4 }, // 0x53 || 0x73
88 { CCCOL_WHITE, CCFONT_REGULAR, 8 }, // 0x54 || 0x74
89 { CCCOL_WHITE, CCFONT_UNDERLINED, 8 }, // 0x55 || 0x75
90 { CCCOL_WHITE, CCFONT_REGULAR, 12 }, // 0x56 || 0x76
91 { CCCOL_WHITE, CCFONT_UNDERLINED, 12 }, // 0x57 || 0x77
92 { CCCOL_WHITE, CCFONT_REGULAR, 16 }, // 0x58 || 0x78
93 { CCCOL_WHITE, CCFONT_UNDERLINED, 16 }, // 0x59 || 0x79
94 { CCCOL_WHITE, CCFONT_REGULAR, 20 }, // 0x5a || 0x7a
95 { CCCOL_WHITE, CCFONT_UNDERLINED, 20 }, // 0x5b || 0x7b
96 { CCCOL_WHITE, CCFONT_REGULAR, 24 }, // 0x5c || 0x7c
97 { CCCOL_WHITE, CCFONT_UNDERLINED, 24 }, // 0x5d || 0x7d
98 { CCCOL_WHITE, CCFONT_REGULAR, 28 }, // 0x5e || 0x7e
99 { CCCOL_WHITE, CCFONT_UNDERLINED, 28 } // 0x5f || 0x7f
100 /* total 32 entries */
103 /* 0-255 needs 256 spaces */
104 static const uint8_t parity_table[256] = { 0, 1, 1, 0, 1, 0, 0, 1,
105 1, 0, 0, 1, 0, 1, 1, 0,
106 1, 0, 0, 1, 0, 1, 1, 0,
107 0, 1, 1, 0, 1, 0, 0, 1,
108 1, 0, 0, 1, 0, 1, 1, 0,
109 0, 1, 1, 0, 1, 0, 0, 1,
110 0, 1, 1, 0, 1, 0, 0, 1,
111 1, 0, 0, 1, 0, 1, 1, 0,
112 1, 0, 0, 1, 0, 1, 1, 0,
113 0, 1, 1, 0, 1, 0, 0, 1,
114 0, 1, 1, 0, 1, 0, 0, 1,
115 1, 0, 0, 1, 0, 1, 1, 0,
116 0, 1, 1, 0, 1, 0, 0, 1,
117 1, 0, 0, 1, 0, 1, 1, 0,
118 1, 0, 0, 1, 0, 1, 1, 0,
119 0, 1, 1, 0, 1, 0, 0, 1,
120 1, 0, 0, 1, 0, 1, 1, 0,
121 0, 1, 1, 0, 1, 0, 0, 1,
122 0, 1, 1, 0, 1, 0, 0, 1,
123 1, 0, 0, 1, 0, 1, 1, 0,
124 0, 1, 1, 0, 1, 0, 0, 1,
125 1, 0, 0, 1, 0, 1, 1, 0,
126 1, 0, 0, 1, 0, 1, 1, 0,
127 0, 1, 1, 0, 1, 0, 0, 1,
128 0, 1, 1, 0, 1, 0, 0, 1,
129 1, 0, 0, 1, 0, 1, 1, 0,
130 1, 0, 0, 1, 0, 1, 1, 0,
131 0, 1, 1, 0, 1, 0, 0, 1,
132 1, 0, 0, 1, 0, 1, 1, 0,
133 0, 1, 1, 0, 1, 0, 0, 1,
134 0, 1, 1, 0, 1, 0, 0, 1,
135 1, 0, 0, 1, 0, 1, 1, 0 };
138 /* +1 is used to compensate null character of string */
139 uint8_t characters[SCREEN_ROWS][SCREEN_COLUMNS+1];
140 uint8_t colors[SCREEN_ROWS][SCREEN_COLUMNS+1];
141 uint8_t fonts[SCREEN_ROWS][SCREEN_COLUMNS+1];
143 * Bitmask of used rows; if a bit is not set, the
144 * corresponding row is not used.
145 * for setting row 1 use row | (1 << 0)
146 * for setting row 15 use row | (1 << 14)
152 typedef struct CCaptionSubContext {
154 struct Screen screen[2];
157 uint8_t cursor_column;
158 uint8_t cursor_color;
165 /* visible screen time */
169 /* buffer to store pkt data */
174 static av_cold int init_decoder(AVCodecContext *avctx)
177 CCaptionSubContext *ctx = avctx->priv_data;
179 av_bprint_init(&ctx->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
180 /* taking by default roll up to 2 */
181 ctx->mode = CCMODE_ROLLUP_2;
183 ret = ff_ass_subtitle_header_default(avctx);
187 /* allocate pkt buffer */
188 ctx->pktbuf = av_buffer_alloc(128);
190 ret = AVERROR(ENOMEM);
195 static av_cold int close_decoder(AVCodecContext *avctx)
197 CCaptionSubContext *ctx = avctx->priv_data;
198 av_bprint_finalize( &ctx->buffer, NULL);
199 av_buffer_unref(&ctx->pktbuf);
204 * @param ctx closed caption context just to print log
206 static int write_char (CCaptionSubContext *ctx, char *row,uint8_t col, char ch)
208 if(col < SCREEN_COLUMNS) {
212 /* We have extra space at end only for null character */
213 else if ( col == SCREEN_COLUMNS && ch == 0) {
218 av_log(ctx, AV_LOG_WARNING,"Data Ignored since exceeding screen width\n");
219 return AVERROR_INVALIDDATA;
224 * This function after validating parity bit, also remove it from data pair.
225 * The first byte doesn't pass parity, we replace it with a solid blank
226 * and process the pair.
227 * If the second byte doesn't pass parity, it returns INVALIDDATA
228 * user can ignore the whole pair and pass the other pair.
230 static int validate_cc_data_pair (uint8_t *cc_data_pair)
232 uint8_t cc_valid = (*cc_data_pair & 4) >>2;
233 uint8_t cc_type = *cc_data_pair & 3;
236 return AVERROR_INVALIDDATA;
238 // if EIA-608 data then verify parity.
239 if (cc_type==0 || cc_type==1) {
240 if (!parity_table[cc_data_pair[2]]) {
241 return AVERROR_INVALIDDATA;
243 if (!parity_table[cc_data_pair[1]]) {
244 cc_data_pair[1]=0x7F;
249 if( (cc_data_pair[0] == 0xFA || cc_data_pair[0] == 0xFC || cc_data_pair[0] == 0xFD )
250 && (cc_data_pair[1] & 0x7F) == 0 && (cc_data_pair[2] & 0x7F) == 0)
251 return AVERROR_PATCHWELCOME;
254 if(cc_type == 3 || cc_type == 2 )
255 return AVERROR_PATCHWELCOME;
257 /* remove parity bit */
258 cc_data_pair[1] &= 0x7F;
259 cc_data_pair[2] &= 0x7F;
266 static struct Screen *get_writing_screen(CCaptionSubContext *ctx)
270 // use Inactive screen
271 return ctx->screen + !ctx->active_screen;
273 case CCMODE_ROLLUP_2:
274 case CCMODE_ROLLUP_3:
275 case CCMODE_ROLLUP_4:
278 return ctx->screen + ctx->active_screen;
280 /* It was never an option */
284 static void roll_up(CCaptionSubContext *ctx)
286 struct Screen *screen;
289 if(ctx->mode == CCMODE_TEXT)
292 screen = get_writing_screen(ctx);
294 /* +1 signify cursor_row starts from 0
295 * Can't keep lines less then row cursor pos
297 keep_lines = FFMIN(ctx->cursor_row + 1, ctx->rollup);
299 for( i = 0; i < ctx->cursor_row - keep_lines; i++ )
300 UNSET_FLAG(screen->row_used, i);
303 for( i = 0; i < keep_lines && screen->row_used; i++ ) {
304 const int i_row = ctx->cursor_row - keep_lines + i + 1;
306 memcpy( screen->characters[i_row], screen->characters[i_row+1], SCREEN_COLUMNS );
307 memcpy( screen->colors[i_row], screen->colors[i_row+1], SCREEN_COLUMNS);
308 memcpy( screen->fonts[i_row], screen->fonts[i_row+1], SCREEN_COLUMNS);
309 if(CHECK_FLAG(screen->row_used, i_row + 1))
310 SET_FLAG(screen->row_used, i_row);
313 UNSET_FLAG(screen->row_used, ctx->cursor_row);
317 static int reap_screen(CCaptionSubContext *ctx, int64_t pts)
321 struct Screen *screen = ctx->screen + ctx->active_screen;
322 ctx->start_time = ctx->startv_time;
324 for( i = 0; screen->row_used && i < SCREEN_ROWS; i++)
326 if(CHECK_FLAG(screen->row_used,i)) {
327 char *str = screen->characters[i];
332 av_bprintf(&ctx->buffer, "%s\\N", str);
333 ret = av_bprint_is_complete(&ctx->buffer);
335 ret = AVERROR(ENOMEM);
341 ctx->startv_time = pts;
346 static void handle_textattr( CCaptionSubContext *ctx, uint8_t hi, uint8_t lo )
350 struct Screen *screen = get_writing_screen(ctx);
351 char *row = screen->characters[ctx->cursor_row];
356 ctx->cursor_color = pac2_attribs[i][0];
357 ctx->cursor_font = pac2_attribs[i][1];
359 SET_FLAG(screen->row_used,ctx->cursor_row);
360 ret = write_char(ctx, row, ctx->cursor_column, ' ');
362 ctx->cursor_column++;
365 static void handle_pac( CCaptionSubContext *ctx, uint8_t hi, uint8_t lo )
367 static const int8_t row_map[] = {
368 11, -1, 1, 2, 3, 4, 12, 13, 14, 15, 5, 6, 7, 8, 9, 10
370 const int index = ( (hi<<1) & 0x0e) | ( (lo>>5) & 0x01 );
371 struct Screen *screen = get_writing_screen(ctx);
375 if( row_map[index] <= 0 ) {
376 av_log(ctx, AV_LOG_DEBUG,"Invalid pac index encountered\n");
382 ctx->cursor_row = row_map[index] - 1;
383 ctx->cursor_color = pac2_attribs[lo][0];
384 ctx->cursor_font = pac2_attribs[lo][1];
385 ctx->cursor_column = 0;
386 indent = pac2_attribs[lo][2];
387 row = screen->characters[ctx->cursor_row];
388 for(i = 0;i < indent; i++) {
389 ret = write_char(ctx, row, ctx->cursor_column, ' ');
391 ctx->cursor_column++;
397 * @param pts it is required to set end time
399 static int handle_edm(CCaptionSubContext *ctx,int64_t pts)
402 struct Screen *screen = ctx->screen + ctx->active_screen;
404 reap_screen(ctx, pts);
405 screen->row_used = 0;
406 ctx->screen_changed = 1;
410 static int handle_eoc(CCaptionSubContext *ctx, int64_t pts)
413 ret = handle_edm(ctx,pts);
414 ctx->active_screen = !ctx->active_screen;
415 ctx->cursor_column = 0;
419 static void handle_delete_end_of_row( CCaptionSubContext *ctx, char hi, char lo)
421 struct Screen *screen = get_writing_screen(ctx);
422 char *row = screen->characters[ctx->cursor_row];
423 write_char(ctx, row, ctx->cursor_column, 0);
427 static void handle_char(CCaptionSubContext *ctx, char hi, char lo, int64_t pts)
429 struct Screen *screen = get_writing_screen(ctx);
430 char *row = screen->characters[ctx->cursor_row];
433 SET_FLAG(screen->row_used,ctx->cursor_row);
435 ret = write_char(ctx, row, ctx->cursor_column, hi);
437 ctx->cursor_column++;
440 ret = write_char(ctx, row, ctx->cursor_column, lo);
442 ctx->cursor_column++;
444 write_char(ctx, row, ctx->cursor_column, 0);
446 /* reset prev command since character can repeat */
447 ctx->prev_cmd[0] = 0;
448 ctx->prev_cmd[1] = 0;
450 av_dlog(ctx, "(%c,%c)\n",hi,lo);
452 av_dlog(ctx, "(%c)\n",hi);
455 static int process_cc608(CCaptionSubContext *ctx, int64_t pts, uint8_t hi, uint8_t lo)
458 #define COR3(var, with1, with2, with3) ( (var) == (with1) || (var) == (with2) || (var) == (with3) )
459 if ( hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) {
460 /* ignore redundant command */
461 } else if ( (hi == 0x10 && (lo >= 0x40 || lo <= 0x5f)) ||
462 ( (hi >= 0x11 && hi <= 0x17) && (lo >= 0x40 && lo <= 0x7f) ) ) {
463 handle_pac(ctx, hi, lo);
464 } else if ( ( hi == 0x11 && lo >= 0x20 && lo <= 0x2f ) ||
465 ( hi == 0x17 && lo >= 0x2e && lo <= 0x2f) ) {
466 handle_textattr(ctx, hi, lo);
467 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x20 ) {
468 /* resume caption loading */
469 ctx->mode = CCMODE_POPON;
470 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x24 ) {
471 handle_delete_end_of_row(ctx, hi, lo);
472 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x25 ) {
474 ctx->mode = CCMODE_ROLLUP_2;
475 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x26 ) {
477 ctx->mode = CCMODE_ROLLUP_3;
478 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x27 ) {
480 ctx->mode = CCMODE_ROLLUP_4;
481 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x29 ) {
482 /* resume direct captioning */
483 ctx->mode = CCMODE_PAINTON;
484 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2B ) {
485 /* resume text display */
486 ctx->mode = CCMODE_TEXT;
487 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2C ) {
488 /* erase display memory */
489 ret = handle_edm(ctx, pts);
490 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2D ) {
491 /* carriage return */
492 av_dlog(ctx, "carriage return\n");
493 reap_screen(ctx, pts);
495 ctx->screen_changed = 1;
496 ctx->cursor_column = 0;
497 } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2F ) {
499 av_dlog(ctx, "handle_eoc\n");
500 ret = handle_eoc(ctx, pts);
501 } else if (hi>=0x20) {
502 /* Standard characters (always in pairs) */
503 handle_char(ctx, hi, lo, pts);
505 /* Ignoring all other non data code */
506 av_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
509 /* set prev command */
510 ctx->prev_cmd[0] = hi;
511 ctx->prev_cmd[1] = lo;
518 static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
520 CCaptionSubContext *ctx = avctx->priv_data;
521 AVSubtitle *sub = data;
522 uint8_t *bptr = NULL;
523 int len = avpkt->size;
527 if ( ctx->pktbuf->size < len) {
528 ret = av_buffer_realloc(&ctx->pktbuf, len);
530 av_log(ctx, AV_LOG_WARNING, "Insufficient Memory of %d truncated to %d\n",len, ctx->pktbuf->size);
531 len = ctx->pktbuf->size;
535 memcpy(ctx->pktbuf->data, avpkt->data, len);
536 bptr = ctx->pktbuf->data;
539 for (i = 0; i < len; i += 3) {
540 uint8_t cc_type = *(bptr + i) & 3;
541 if (validate_cc_data_pair( bptr + i) )
543 /* ignoring data field 1 */
547 process_cc608(ctx, avpkt->pts, *(bptr + i + 1) & 0x7f, *(bptr + i + 2) & 0x7f);
548 if(ctx->screen_changed && *ctx->buffer.str)
550 int start_time = av_rescale_q(ctx->start_time, avctx->time_base, (AVRational){ 1, 100 });
551 int end_time = av_rescale_q(ctx->end_time, avctx->time_base, (AVRational){ 1, 100 });
552 av_dlog(ctx, "cdp writing data (%s)\n",ctx->buffer.str);
553 ret = ff_ass_add_rect(sub, ctx->buffer.str, start_time, end_time - start_time , 0);
556 sub->pts = av_rescale_q(ctx->start_time, avctx->time_base, AV_TIME_BASE_Q);
557 ctx->screen_changed = 0;
558 av_bprint_clear(&ctx->buffer);
562 *got_sub = sub->num_rects > 0;
566 static const AVOption options[] = {
570 static const AVClass ccaption_dec_class = {
571 .class_name = "Closed caption Decoder",
572 .item_name = av_default_item_name,
574 .version = LIBAVUTIL_VERSION_INT,
577 AVCodec ff_ccaption_decoder = {
579 .long_name = NULL_IF_CONFIG_SMALL("Closed Caption (EIA-608 / CEA-708) Decoder"),
580 .type = AVMEDIA_TYPE_SUBTITLE,
581 .id = AV_CODEC_ID_EIA_608,
582 .priv_data_size = sizeof(CCaptionSubContext),
583 .init = init_decoder,
584 .close = close_decoder,
586 .priv_class = &ccaption_dec_class,