/* * Closed Caption Decoding * Copyright (c) 2015 Anshul Maheshwari * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "avcodec.h" #include "ass.h" #include "libavutil/opt.h" #define CHAR_DEBUG #define SCREEN_ROWS 15 #define SCREEN_COLUMNS 32 #define SET_FLAG(var, val) ( (var) |= ( 1 << (val)) ) #define UNSET_FLAG(var, val) ( (var) &= ~( 1 << (val)) ) #define CHECK_FLAG(var, val) ( (var) & ( 1 << (val)) ) /* * TODO list * 1) handle font and color completely */ enum cc_mode { CCMODE_POPON, CCMODE_PAINTON, CCMODE_ROLLUP_2, CCMODE_ROLLUP_3, CCMODE_ROLLUP_4, CCMODE_TEXT, }; enum cc_color_code { CCCOL_WHITE, CCCOL_GREEN, CCCOL_BLUE, CCCOL_CYAN, CCCOL_RED, CCCOL_YELLOW, CCCOL_MAGENTA, CCCOL_USERDEFINED, CCCOL_BLACK, CCCOL_TRANSPARENT, }; enum cc_font { CCFONT_REGULAR, CCFONT_ITALICS, CCFONT_UNDERLINED, CCFONT_UNDERLINED_ITALICS, }; static const unsigned char pac2_attribs[][3] = // Color, font, ident { { CCCOL_WHITE, CCFONT_REGULAR, 0 }, // 0x40 || 0x60 { CCCOL_WHITE, CCFONT_UNDERLINED, 0 }, // 0x41 || 0x61 { CCCOL_GREEN, CCFONT_REGULAR, 0 }, // 0x42 || 0x62 { CCCOL_GREEN, CCFONT_UNDERLINED, 0 }, // 0x43 || 0x63 { CCCOL_BLUE, CCFONT_REGULAR, 0 }, // 0x44 || 0x64 { CCCOL_BLUE, CCFONT_UNDERLINED, 0 }, // 0x45 || 0x65 { CCCOL_CYAN, CCFONT_REGULAR, 0 }, // 0x46 || 0x66 { CCCOL_CYAN, CCFONT_UNDERLINED, 0 }, // 0x47 || 0x67 { CCCOL_RED, CCFONT_REGULAR, 0 }, // 0x48 || 0x68 { CCCOL_RED, CCFONT_UNDERLINED, 0 }, // 0x49 || 0x69 { CCCOL_YELLOW, CCFONT_REGULAR, 0 }, // 0x4a || 0x6a { CCCOL_YELLOW, CCFONT_UNDERLINED, 0 }, // 0x4b || 0x6b { CCCOL_MAGENTA, CCFONT_REGULAR, 0 }, // 0x4c || 0x6c { CCCOL_MAGENTA, CCFONT_UNDERLINED, 0 }, // 0x4d || 0x6d { CCCOL_WHITE, CCFONT_ITALICS, 0 }, // 0x4e || 0x6e { CCCOL_WHITE, CCFONT_UNDERLINED_ITALICS, 0 }, // 0x4f || 0x6f { CCCOL_WHITE, CCFONT_REGULAR, 0 }, // 0x50 || 0x70 { CCCOL_WHITE, CCFONT_UNDERLINED, 0 }, // 0x51 || 0x71 { CCCOL_WHITE, CCFONT_REGULAR, 4 }, // 0x52 || 0x72 { CCCOL_WHITE, CCFONT_UNDERLINED, 4 }, // 0x53 || 0x73 { CCCOL_WHITE, CCFONT_REGULAR, 8 }, // 0x54 || 0x74 { CCCOL_WHITE, CCFONT_UNDERLINED, 8 }, // 0x55 || 0x75 { CCCOL_WHITE, CCFONT_REGULAR, 12 }, // 0x56 || 0x76 { CCCOL_WHITE, CCFONT_UNDERLINED, 12 }, // 0x57 || 0x77 { CCCOL_WHITE, CCFONT_REGULAR, 16 }, // 0x58 || 0x78 { CCCOL_WHITE, CCFONT_UNDERLINED, 16 }, // 0x59 || 0x79 { CCCOL_WHITE, CCFONT_REGULAR, 20 }, // 0x5a || 0x7a { CCCOL_WHITE, CCFONT_UNDERLINED, 20 }, // 0x5b || 0x7b { CCCOL_WHITE, CCFONT_REGULAR, 24 }, // 0x5c || 0x7c { CCCOL_WHITE, CCFONT_UNDERLINED, 24 }, // 0x5d || 0x7d { CCCOL_WHITE, CCFONT_REGULAR, 28 }, // 0x5e || 0x7e { CCCOL_WHITE, CCFONT_UNDERLINED, 28 } // 0x5f || 0x7f /* total 32 entries */ }; /* 0-255 needs 256 spaces */ static const uint8_t parity_table[256] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 }; struct Screen { /* +1 is used to compensate null character of string */ uint8_t characters[SCREEN_ROWS][SCREEN_COLUMNS+1]; /* * Bitmask of used rows; if a bit is not set, the * corresponding row is not used. * for setting row 1 use row | (1 << 0) * for setting row 15 use row | (1 << 14) */ int16_t row_used; }; typedef struct CCaptionSubContext { AVClass *class; int row_cnt; struct Screen screen[2]; int active_screen; uint8_t cursor_row; uint8_t cursor_column; uint8_t cursor_color; uint8_t cursor_font; AVBPrint buffer; int erase_display_memory; int rollup; enum cc_mode mode; int64_t start_time; /* visible screen time */ int64_t startv_time; int64_t end_time; char prev_cmd[2]; /* buffer to store pkt data */ AVBufferRef *pktbuf; }CCaptionSubContext; static av_cold int init_decoder(AVCodecContext *avctx) { int ret; CCaptionSubContext *ctx = avctx->priv_data; av_bprint_init(&ctx->buffer, 0, AV_BPRINT_SIZE_UNLIMITED); /* taking by default roll up to 2 */ ctx->rollup = 2; ret = ff_ass_subtitle_header_default(avctx); /* allocate pkt buffer */ ctx->pktbuf = av_buffer_alloc(128); if( !ctx->pktbuf) { ret = AVERROR(ENOMEM); } return ret; } static av_cold int close_decoder(AVCodecContext *avctx) { CCaptionSubContext *ctx = avctx->priv_data; av_bprint_finalize( &ctx->buffer, NULL); av_buffer_unref(&ctx->pktbuf); return 0; } /** * @param ctx closed caption context just to print log */ static int write_char (CCaptionSubContext *ctx, char *row,uint8_t col, char ch) { if(col < SCREEN_COLUMNS) { row[col] = ch; return 0; } /* We have extra space at end only for null character */ else if ( col == SCREEN_COLUMNS && ch == 0) { row[col] = ch; return 0; } else { av_log(ctx, AV_LOG_WARNING,"Data Ignored since exceeding screen width\n"); return AVERROR_INVALIDDATA; } } /** * This function after validating parity bit, also remove it from data pair. * The first byte doesn't pass parity, we replace it with a solid blank * and process the pair. * If the second byte doesn't pass parity, it returns INVALIDDATA * user can ignore the whole pair and pass the other pair. */ static int validate_cc_data_pair (uint8_t *cc_data_pair) { uint8_t cc_valid = (*cc_data_pair & 4) >>2; uint8_t cc_type = *cc_data_pair & 3; if (!cc_valid) return AVERROR_INVALIDDATA; // if EIA-608 data then verify parity. if (cc_type==0 || cc_type==1) { if (!parity_table[cc_data_pair[2]]) { return AVERROR_INVALIDDATA; } if (!parity_table[cc_data_pair[1]]) { cc_data_pair[1]=0x7F; } } //Skip non-data if( (cc_data_pair[0] == 0xFA || cc_data_pair[0] == 0xFC || cc_data_pair[0] == 0xFD ) && (cc_data_pair[1] & 0x7F) == 0 && (cc_data_pair[2] & 0x7F) == 0) return AVERROR_PATCHWELCOME; //skip 708 data if(cc_type == 3 || cc_type == 2 ) return AVERROR_PATCHWELCOME; /* remove parity bit */ cc_data_pair[1] &= 0x7F; cc_data_pair[2] &= 0x7F; return 0; } static struct Screen *get_writing_screen(CCaptionSubContext *ctx) { switch (ctx->mode) { case CCMODE_POPON: // use Inactive screen return ctx->screen + !ctx->active_screen; case CCMODE_PAINTON: case CCMODE_ROLLUP_2: case CCMODE_ROLLUP_3: case CCMODE_ROLLUP_4: case CCMODE_TEXT: // use active screen return ctx->screen + ctx->active_screen; } /* It was never an option */ return NULL; } static void handle_textattr( CCaptionSubContext *ctx, uint8_t hi, uint8_t lo ) { int i = lo - 0x20; int ret; struct Screen *screen = get_writing_screen(ctx); char *row = screen->characters[ctx->cursor_row]; if( i >= 32) return; ctx->cursor_color = pac2_attribs[i][0]; ctx->cursor_font = pac2_attribs[i][1]; SET_FLAG(screen->row_used,ctx->cursor_row); ret = write_char(ctx, row, ctx->cursor_column, ' '); if(ret == 0) ctx->cursor_column++; } static void handle_pac( CCaptionSubContext *ctx, uint8_t hi, uint8_t lo ) { static const int8_t row_map[] = { 11, -1, 1, 2, 3, 4, 12, 13, 14, 15, 5, 6, 7, 8, 9, 10 }; const int index = ( (hi<<1) & 0x0e) | ( (lo>>5) & 0x01 ); struct Screen *screen = get_writing_screen(ctx); char *row; int indent,i,ret; if( row_map[index] <= 0 ) return; lo &= 0x1f; ctx->cursor_row = row_map[index] - 1; ctx->cursor_color = pac2_attribs[lo][0]; ctx->cursor_font = pac2_attribs[lo][1]; ctx->cursor_column = 0; indent = pac2_attribs[lo][2]; row = screen->characters[ctx->cursor_row]; for(i = 0;i < indent; i++) { ret = write_char(ctx, row, ctx->cursor_column, ' '); if( ret == 0 ) ctx->cursor_column++; } } /** * @param pts it is required to set end time */ static int handle_edm(CCaptionSubContext *ctx,int64_t pts) { int i; int ret = 0; struct Screen *screen = ctx->screen + ctx->active_screen; ctx->start_time = ctx->startv_time; for( i = 0; screen->row_used && i < SCREEN_ROWS; i++) { if(CHECK_FLAG(screen->row_used,i)) { char *str = screen->characters[i]; /* skip space */ while (*str == ' ') str++; av_bprint_append_data(&ctx->buffer, str, strlen(str)); av_bprint_append_data(&ctx->buffer, "\\N",2); UNSET_FLAG(screen->row_used, i); ret = av_bprint_is_complete(&ctx->buffer); if( ret == 0) { ret = AVERROR(ENOMEM); break; } } } ctx->startv_time = pts; ctx->erase_display_memory = 1; ctx->end_time = pts; return ret; } static int handle_eoc(CCaptionSubContext *ctx, int64_t pts) { int ret; ret = handle_edm(ctx,pts); ctx->active_screen = !ctx->active_screen; ctx->cursor_column = 0; return ret; } static void handle_delete_end_of_row( CCaptionSubContext *ctx, char hi, char lo) { struct Screen *screen = get_writing_screen(ctx); char *row = screen->characters[ctx->cursor_row]; write_char(ctx, row, ctx->cursor_column, 0); } static void handle_char(CCaptionSubContext *ctx, char hi, char lo, int64_t pts) { struct Screen *screen = get_writing_screen(ctx); char *row = screen->characters[ctx->cursor_row]; int ret; SET_FLAG(screen->row_used,ctx->cursor_row); ret = write_char(ctx, row, ctx->cursor_column, hi); if( ret == 0 ) ctx->cursor_column++; if(lo) { ret = write_char(ctx, row, ctx->cursor_column, lo); if ( ret == 0 ) ctx->cursor_column++; } write_char(ctx, row, ctx->cursor_column, 0); /* reset prev command since character can repeat */ ctx->prev_cmd[0] = 0; ctx->prev_cmd[1] = 0; #ifdef CHAR_DEBUG av_log(ctx, AV_LOG_DEBUG,"(%c,%c)\n",hi,lo); #endif } static int process_cc608(CCaptionSubContext *ctx, int64_t pts, uint8_t hi, uint8_t lo) { int ret = 0; #define COR3(var, with1, with2, with3) ( (var) == (with1) || (var) == (with2) || (var) == (with3) ) if ( hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) { /* ignore redundant command */ } else if ( (hi == 0x10 && (lo >= 0x40 || lo <= 0x5f)) || ( (hi >= 0x11 && hi <= 0x17) && (lo >= 0x40 && lo <= 0x7f) ) ) { handle_pac(ctx, hi, lo); } else if ( ( hi == 0x11 && lo >= 0x20 && lo <= 0x2f ) || ( hi == 0x17 && lo >= 0x2e && lo <= 0x2f) ) { handle_textattr(ctx, hi, lo); } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x20 ) { /* resume caption loading */ ctx->mode = CCMODE_POPON; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x24 ) { handle_delete_end_of_row(ctx, hi, lo); } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x25 ) { ctx->rollup = 2; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x26 ) { ctx->rollup = 3; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x27 ) { ctx->rollup = 4; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x29 ) { /* resume direct captioning */ ctx->mode = CCMODE_PAINTON; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2B ) { /* resume text display */ ctx->mode = CCMODE_TEXT; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2C ) { /* erase display memory */ ret = handle_edm(ctx, pts); } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2D ) { /* carriage return */ ctx->row_cnt++; if(ctx->row_cnt >= ctx->rollup) { ctx->row_cnt = 0; ret = handle_edm(ctx, pts); ctx->active_screen = !ctx->active_screen; } ctx->cursor_column = 0; } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2F ) { /* end of caption */ ret = handle_eoc(ctx, pts); } else if (hi>=0x20) { /* Standard characters (always in pairs) */ handle_char(ctx, hi, lo, pts); } else { /* Ignoring all other non data code */ } /* set prev command */ ctx->prev_cmd[0] = hi; ctx->prev_cmd[1] = lo; #undef COR3 return ret; } static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt) { CCaptionSubContext *ctx = avctx->priv_data; AVSubtitle *sub = data; uint8_t *bptr = NULL; int len = avpkt->size; int ret = 0; int i; if ( ctx->pktbuf->size < len) { ret = av_buffer_realloc(&ctx->pktbuf, len); if(ret < 0) { av_log(ctx, AV_LOG_WARNING, "Insufficient Memory of %d truncated to %d\n",len, ctx->pktbuf->size); len = ctx->pktbuf->size; ret = 0; } } memcpy(ctx->pktbuf->data, avpkt->data, len); bptr = ctx->pktbuf->data; for (i = 0; i < len; i += 3) { uint8_t cc_type = *(bptr + i) & 3; if (validate_cc_data_pair( bptr + i) ) continue; /* ignoring data field 1 */ if(cc_type == 1) continue; else process_cc608(ctx, avpkt->pts, *(bptr + i + 1) & 0x7f, *(bptr + i + 2) & 0x7f); if(ctx->erase_display_memory && *ctx->buffer.str) { int start_time = av_rescale_q(ctx->start_time, avctx->time_base, (AVRational){ 1, 100 }); int end_time = av_rescale_q(ctx->end_time, avctx->time_base, (AVRational){ 1, 100 }); #ifdef CHAR_DEBUG av_log(ctx, AV_LOG_DEBUG,"cdp writing data (%s)\n",ctx->buffer.str); #endif ret = ff_ass_add_rect(sub, ctx->buffer.str, start_time, end_time - start_time , 0); if (ret < 0) return ret; sub->pts = av_rescale_q(ctx->start_time, avctx->time_base, AV_TIME_BASE_Q); ctx->erase_display_memory = 0; av_bprint_clear(&ctx->buffer); } } *got_sub = sub->num_rects > 0; return ret; } static const AVOption options[] = { {NULL} }; static const AVClass ccaption_dec_class = { .class_name = "Closed caption Decoder", .item_name = av_default_item_name, .option = options, .version = LIBAVUTIL_VERSION_INT, }; AVCodec ff_ccaption_decoder = { .name = "cc_dec", .long_name = NULL_IF_CONFIG_SMALL("Closed Caption (EIA-608 / CEA-708) Decoder"), .type = AVMEDIA_TYPE_SUBTITLE, .id = AV_CODEC_ID_EIA_608, .priv_data_size = sizeof(CCaptionSubContext), .init = init_decoder, .close = close_decoder, .decode = decode, .priv_class = &ccaption_dec_class, };