/*
* 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/internal.h"
#include "libavutil/opt.h"
#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[32][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];
uint8_t colors[SCREEN_ROWS][SCREEN_COLUMNS+1];
uint8_t fonts[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;
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 screen_changed;
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->mode = CCMODE_ROLLUP_2;
ctx->rollup = 2;
ret = ff_ass_subtitle_header_default(avctx);
if(ret < 0) {
return ret;
}
/* 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 roll_up(CCaptionSubContext *ctx)
{
struct Screen *screen;
int i, keep_lines;
if(ctx->mode == CCMODE_TEXT)
return;
screen = get_writing_screen(ctx);
/* +1 signify cursor_row starts from 0
* Can't keep lines less then row cursor pos
*/
keep_lines = FFMIN(ctx->cursor_row + 1, ctx->rollup);
for( i = 0; i < ctx->cursor_row - keep_lines; i++ )
UNSET_FLAG(screen->row_used, i);
for( i = 0; i < keep_lines && screen->row_used; i++ ) {
const int i_row = ctx->cursor_row - keep_lines + i + 1;
memcpy( screen->characters[i_row], screen->characters[i_row+1], SCREEN_COLUMNS );
memcpy( screen->colors[i_row], screen->colors[i_row+1], SCREEN_COLUMNS);
memcpy( screen->fonts[i_row], screen->fonts[i_row+1], SCREEN_COLUMNS);
if(CHECK_FLAG(screen->row_used, i_row + 1))
SET_FLAG(screen->row_used, i_row);
}
UNSET_FLAG(screen->row_used, ctx->cursor_row);
}
static int reap_screen(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_bprintf(&ctx->buffer, "%s\\N", str);
ret = av_bprint_is_complete(&ctx->buffer);
if( ret == 0) {
ret = AVERROR(ENOMEM);
break;
}
}
}
if(screen->row_used && ctx->buffer.len >= 2 ) {
ctx->buffer.len -= 2;
ctx->buffer.str[ctx->buffer.len] = 0;
}
ctx->startv_time = pts;
ctx->end_time = pts;
return ret;
}
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 ) {
av_log(ctx, AV_LOG_DEBUG,"Invalid pac index encountered\n");
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 ret = 0;
struct Screen *screen = ctx->screen + ctx->active_screen;
reap_screen(ctx, pts);
screen->row_used = 0;
ctx->screen_changed = 1;
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;
if (lo)
ff_dlog(ctx, "(%c,%c)\n",hi,lo);
else
ff_dlog(ctx, "(%c)\n",hi);
}
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;
ctx->mode = CCMODE_ROLLUP_2;
} else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x26 ) {
ctx->rollup = 3;
ctx->mode = CCMODE_ROLLUP_3;
} else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x27 ) {
ctx->rollup = 4;
ctx->mode = CCMODE_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 */
ff_dlog(ctx, "carriage return\n");
reap_screen(ctx, pts);
roll_up(ctx);
ctx->screen_changed = 1;
ctx->cursor_column = 0;
} else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2F ) {
/* end of caption */
ff_dlog(ctx, "handle_eoc\n");
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 */
ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
}
/* 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->screen_changed && *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 });
ff_dlog(ctx, "cdp writing data (%s)\n",ctx->buffer.str);
ret = ff_ass_add_rect_bprint(sub, &ctx->buffer, start_time, end_time - start_time);
if (ret < 0)
return ret;
sub->pts = av_rescale_q(ctx->start_time, avctx->time_base, AV_TIME_BASE_Q);
ctx->screen_changed = 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,
};